A RISC-V IoT Development Board

Most of us will not know about RISC-V, or have had access to a RISC-V Chip.
This will thus be truly one of the most difficult posts I have written, due to many factors…

To name a few of these:
– The learning curve is extremely steep because there is extremely limited information available on the chip
– I can not at the moment allowed to divulge any information on the chip used, as I have received a few “sneak-preview” modules, and the manufacturer, who shall also remain anonymous for now, has not released it to the public yet.
– Most of the information available on the BL-602 ( on which the chip is based) is in relation to the BL-IOT-SDK, or Apache NuttX, an RTOS for use with microcontrollers.
While the NuttX project has excellent documentation, it is written in a very technical style, and focused on very basic, very advanced or very specific things. This will hopefully be improved upon to make it more “new-end-user-that-is-learning” friendly in future.

As most of us can no doubt see, This post is quite a challenge. I will thus focus on the PCB I designed to use with the “mystery BL-602” chip, and provide a lot of links to where you can get information on Apache NuttX, as well as how to use it with the BL-602 in general.

Once the module has been officially released, I will do a followup-post, with specific documentation etc, which, although I have already got some of it in my possession, I can not release at the moment for ethical reasons.

I think it fair to tell you all this much, and , unintentionally, have to create anticipation on what and where etc… My apologies for that, but rules are rules, and secrets are meant to be kept, until told otherwise…

So, lets get started. Some links to get you started and show you where this is going…

Apache Nuttx is the RTOS that you will most likely have to use to do anything useful with the BL-602 chip, as well as other microcontrollers, notably the ESP32-S3 and some of the STM32 chips.

Bouffalo Labs are the people behind the BL-602, as well as the BL-IOT-SDK, which will also be quite useful in designing solutions around the BL-602

Run Rust on RISC-V Firmware will provide some excellent points to get started

LEE Lup Yuen seems to be the kind person who has written most of the extensive and useful documentation on NuttX and the BL-602, amongst others…

NuttX Incubator on Github is a very detailed source, also by Mr Lee Lup Yuen, that aims to get us started with the BL-602 and NuttX – This link is HIGHLY recommended!

My Prototype PCB

Carrier PCB – Disclaimer – I have edited the silkscreen to remove Chip markings- This will be released to the public at a later stage. As mentioned above, it is necessary at this moment to keep this information confidential.

I decided to design an extremely basic, bare PCB with basically just the BL-602 chip and its supporting circuitry. This will allow me to focus only on the chip, as well as provide maximum flexibility in the future by the addition of add-on shields with specific functions. with this in mind, I purposely chose a PCB footprint similar to the Arduino UNO.

It is also worth mentioning that the chip module used on this PCB IS NOT a standard BL-602, although the footprint looks similar.

At the moment, I am however pulled between being frustrated at the lack of available information and also being excited at the possibilities that are already there or will open up in the future.

Needless to say, some people will be frustrated at the “seeming lack of details in this post”. Lets all stay calm, and remember that I will post a followup, with all the details soon.

Manufacturing

Over the past eight years, PCBWay has continuously upgraded their MANUFACTURING plants and equipment to meet higher quality requirements, and now THEY also provide OEM services to build your products from ideas to mass production and access to the market.


The PCB for this project has been manufactured at PCBWay.
Please consider supporting them if you would like your own copy of this PCB, or if you have any PCB of your own that you need to have manufactured.

PCBWay

If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
1) Click on this link
2) Create an account if you have not already got one of your own.
If you use the link above, you will also instantly receive a $5 USD coupon, which you can use on your first or any other order later. (Disclaimer: I will earn a small referral fee from PCBWay. This referral fee will not affect the cost of your order, nor will you pay any part thereof.)
3) Once you have gone to their website, and created an account, or login with your existing account,

4) Click on PCB Instant Quote

5) If you do not have any very special requirements for your PCB, click on Quick-order PCB

6) Click on Add Gerber File, and select your Gerber file(s) from your computer. Most of your PCB details will now be automatically selected, leaving you to only select the solder mask and silk-screen colour, as well as to remove the order number or not. You can of course fine-tune everything exactly as you want as well.

7) You can also select whether you want an SMD stencil, or have the board assembled after manufacturing. Please note that the assembly service, as well as the cost of your components, ARE NOT included in the initial quoted price. ( The quote will update depending on what options you select ).

8) When you are happy with the options that you have selected, you can click on the Save to Cart Button. From here on, you can go to the top of the screen, click on Cart, make any payment(s) or use any coupons that you have in your account.

Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

ATMega 328P Based PWM controller Card

As part of my recent ESP-12E I2C Base Board project, I designed an ATMega 328P Based PWM controller card, that can be used as an add-on card with the existing project, or standalone as a custom Arduino Nano compatible development board.

What is on the PCB?

The PWM controller card contains standard Arduino Nano circuitry running at 16MHz, without the USB to Serial converter, as well as a 3v to 5v level converter on the I2C port ( A4 and A5 ), as well as another 12v to 5v level converter, with a build in resistor-divider circuit, used to drive a 12v blower with 3.3v PWM control circuitry.

All analog inputs are broken out to make attaching additional sensors easier.

All the other unused GPIO pins are also broken out, either directly to headers on the PCB (D6~,D7,D8,D9~), D11,D12,D12 (ISCP Header) and D3 ( Marked RPM on the Fan Header)

Most of these pins are also additionally broken out onto the 2x20p female header at the bottom of the card ( See schematic for more details)

The board is designed to be powered from 12v DC (via the VIN pins on the 2x20p header) which is internally regulated down to 5v via an LDO voltage regulator.


External 3.3v should also be supplied to the 2x20Pin header to enable the I2C level converters on the same header. I2C is not directly broken out onto the PCB in this version of the PCB.

A reset button, and power led, as well as the standard led on D13 is also provided.

Manufacturing the PCB


Over the past eight years, PCBWay has continuously upgraded their MANUFACTURING plants and equipment to meet higher quality requirements, and now THEY also provide OEM services to build your products from ideas to mass production and access to the market.


The PCB for this project has been manufactured at PCBWay.
Please consider supporting them if you would like your own copy of this PCB, or if you have any PCB of your own that you need to have manufactured.

PCBWay

If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
1) Click on this link
2) Create an account if you have not already got one of your own.
If you use the link above, you will also instantly receive a $5 USD coupon, which you can use on your first or any other order later. (Disclaimer: I will earn a small referral fee from PCBWay. This referral fee will not affect the cost of your order, nor will you pay any part thereof.)
3) Once you have gone to their website, and created an account, or login with your existing account,

4) Click on PCB Instant Quote

5) If you do not have any very special requirements for your PCB, click on Quick-order PCB

6) Click on Add Gerber File, and select your Gerber file(s) from your computer. Most of your PCB details will now be automatically selected, leaving you to only select the solder mask and silk-screen colour, as well as to remove the order number or not. You can of course fine-tune everything exactly as you want as well.

7) You can also select whether you want an SMD stencil, or have the board assembled after manufacturing. Please note that the assembly service, as well as the cost of your components, ARE NOT included in the initial quoted price. ( The quote will update depending on what options you select ).

8) When you are happy with the options that you have selected, you can click on the Save to Cart Button. From here on, you can go to the top of the screen, click on Cart, make any payment(s) or use any coupons that you have in your account.

Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

VC-01 and VC-02 Offline Voice Module

In a recent article, I took a look at the new VC-01 and VC-02 Voice offline voice modules from AI-Thinker. I mentioned that I was working on a very simple prototype PCB to do some more tests, as well as make practical use of the module in real life.

In this very short post, I will show off the initial prototype that I came up with.
While I have to admit that it is still in an extremely basic stage, It is already definitely useful.

Part of the reason for this is that there is not a lot of information available on the VC-01 and VC-02 at this stage, as well as the fact that more exotic features like I2C and SPI are still not accessible in the current firmware. I thus had to work with what was available, as well as take into consideration what will work with the standard factory firmware as well.

The prototype carrier PCB will thus only have two optically isolated relays and their supporting circuitry. I intend to actually use the PCB in my EE LAb area to control some of the lights in the area.

The Schematic

The schematic shows the relay control circuitry, comprising of my standard optic isolator-based relay driver, as well as headers to accept the VC-01 or VC-02 offline voice module kit PCB.

Testing the PCB

The PCB was tested using the standard factory firmware, as well as my custom firmware, kindly provided by AI-Thinker. Below is a short video of that in action. Please note that the relays was not yet connected to any external devices at this stage.

Manufacturing the PCB


Over the past eight years, PCBWay has continuously upgraded their MANUFACTURING plants and equipment to meet higher quality requirements, and now THEY also provide OEM services to build your products from ideas to mass production and access to the market.


The PCB for this project has been manufactured at PCBWay.
Please consider supporting them if you would like your own copy of this PCB, or if you have any PCB of your own that you need to have manufactured.

PCBWay

If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
1) Click on this link
2) Create an account if you have not already got one of your own.
If you use the link above, you will also instantly receive a $5 USD coupon, which you can use on your first or any other order later. (Disclaimer: I will earn a small referral fee from PCBWay. This referral fee will not affect the cost of your order, nor will you pay any part thereof.)
3) Once you have gone to their website, and created an account, or login with your existing account,

4) Click on PCB Instant Quote

5) If you do not have any very special requirements for your PCB, click on Quick-order PCB

6) Click on Add Gerber File, and select your Gerber file(s) from your computer. Most of your PCB details will now be automatically selected, leaving you to only select the solder mask and silk-screen colour, as well as to remove the order number or not. You can of course fine-tune everything exactly as you want as well.

7) You can also select whether you want an SMD stencil, or have the board assembled after manufacturing. Please note that the assembly service, as well as the cost of your components, ARE NOT included in the initial quoted price. ( The quote will update depending on what options you select ).

8) When you are happy with the options that you have selected, you can click on the Save to Cart Button. From here on, you can go to the top of the screen, click on Cart, make any payment(s) or use any coupons that you have in your account.

Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

True OFFLINE Voice Assistant

Most of us are familiar with voice assistants these days; Google Assistant, Siri and Alexa are obviously the most well-known of these. They all share a common problem though: They are online, and can thus secretly record everything you say around them, for later use by their respective owners [ The Companies that created them ]. Having a true offline voice assistant can thus seem like the holy grail for privacy and security-minded people.

Introducing VC-01/VC-02

I was recently contacted by AI-Thinker and asked if I was interested to play with a new product of theirs, an offline voice module. I immediately jumped at the opportunity, as this was something that I wanted to get my hands on for a long time, providing it works of course…

AI-Thinker’s offline voice module is available in two models, the VC-01 and the VC-02.

My Sales Representative (Kat ) sent me both models, in a kit format, complete with speaker and microphone. The kit PCB also provides a USB port with a ch340 chip, as well as two push buttons (reset and wake-up) as well as 3 built-in LEDs ( White, Orange and Blue ).

These light up with the factory firmware, depending on what commands are issued to the device…

Let us take a look at how the factory firmware works; Thank you to Kat from Ai-Thinker for uploading the video, and sending the link to me 🙂

As we can see in the video above, the module seems to work very well… The question now arises if it can be customised to do what we want it to…

Custom Firmware – Do-able, but with a few caveats

Information in English on this module is very sparse. This is due to it being very new, and with AI-Thinker focusing most of their efforts for this module on the Chinese market for the time being. Which makes sense in one way, but also doesn’t in another.

After spending quite a bit of time trying to get information, my Sales Rep eventually gave me access to an online configuration utility, now be warned:
This is not for the faint of heart. The entire interface is in Chinese ( They are working on an English version, with time-to-completion between one (1) to four(4) weeks from starting the project. I can however not give any accurate dates at this stage, but was told that this development is underway).

Being no stranger to different languages, I thought to use google translate to translate the website. No, that didn’t work. Google refuses or the Chinese Website doesn’t allow it to? No answer as of yet. Any readers who do know any reasons for this, please comment below.

I was sort of successful in manually copy pasting line by line into google translate and got some translation back, but it was not very useful.

My next point to try was asking AI-Thinker to generate some firmware with the web tool. They gladly did that, and that works great. It is however not feasible in the long term to go that route every time.

This was possible because the AI-Thinker engineers, using the firmware development software, currently only available in Chinese, can set custom wake words and train voice commands with a 95% accuracy rate, before generating firmware and flashing it onto the respective module.


Write your own, someone will obviously say, and that was my next attempt. There is an API, and source code on GitHub, as well as Gitee ( The Chinese version of GitHub) The two sources are however not synced, and I was still not successful in getting anything useful from Gitee, once again due to a language issue, as well as the fact that some of the sources depend on 32bit dependencies for Ubuntu, whereas I am running a 64bit version… I did try it though, and can not report any success on that venture at all.

Once again, I will advice us all to wait for AI-Thinker to release an English version of the SDK and API for us all to use, which I am sure they will do at some stage in the near future.

See the video below of my custom firmware, once again demonstrated by Kat from AI-Thinker

Custom Firmware – Test 01

As we can see, it once again performs well, with a few issues, but quite acceptable…

Hardware access to the real world

As we have just seen in the video, there is also hardware access via pins, to the real world. There are however a few issues there as well…

Hardware pins are limited.
I2C and SPI, although advertised, are apparently not yet supported in any of the current firmware – Someone with information, please comment…

While there are 2 I2C interfaces, they can not be used at the same time
Information on the module

PCB Prototype – Of my own design

As a proof of concept, I have decided to design a quick prototype with relays to use as a more detailed test. I will update information on that soon…

My Conclusion

I definitely see potential here. This is a product which can be quite useful in the future, providing that the following is done:

Proper detailed documentation is provided in English as well as Chinese
API and SDK access is made available in English as well as Chinese
Firmware be updated to make all features available

Having said all of that, I do understand that development, and especially R&D do take a lot of time. Translating documents accurately does too.

I want to congratulate AI-Thinker on producing a very well-made unit, that will definitely bring the dream of a totally offline voice assistant a little bit closer to being a reality.

Voice recognition with my bastard South-African/British English Accent, heavily influenced by Afrikaans, went extremely well, even with the factory firmware.
I do thus not think anybody that can speak passable English will have a problem using the unit.


ESP-12E I2C Base Card

As a follow-up on the ESP-12E Card, today we will look at the prototype base card that this was designed to slot into – The ESP-12E I2c Base Card.

Initial Features ( To be expanded in future versions )

4 x 40Pin Expansion slots, with access to 12v, 3.3v and Gnd on each slot.
2 x “IRQ” pins per slot ( serviced by a single PCF8574 )
I2C bus access on each slot (3.3v )
UART Header
Reset and Flash Header
GPIO Header ( Direct access to the ESP-12E GPIO Pins )
Analog Input Header (a Single input – A0, as per ESP-12E limitation)
Buck Converter Power Supply Module, capable of up to 2A of current

ESP-12E I2C Base Card – Top view

The Schematic

Schematic

The PCB – some pictures

ESP 12-E Card with Base Board

Manufacturing the PCB


Over the past eight years, PCBWay has continuously upgraded their MANUFACTURING plants and equipment to meet higher quality requirements, and now THEY also provide OEM services to build your products from ideas to mass production and access to the market.


The PCB for this project has been manufactured at PCBWay.
Please consider supporting them if you would like your own copy of this PCB, or if you have any PCB of your own that you need to have manufactured.

PCBWay

If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
1) Click on this link
2) Create an account if you have not already got one of your own.
If you use the link above, you will also instantly receive a $5 USD coupon, which you can use on your first or any other order later. (Disclaimer: I will earn a small referral fee from PCBWay. This referral fee will not affect the cost of your order, nor will you pay any part thereof.)
3) Once you have gone to their website, and created an account, or login with your existing account,

4) Click on PCB Instant Quote

5) If you do not have any very special requirements for your PCB, click on Quick-order PCB

6) Click on Add Gerber File, and select your Gerber file(s) from your computer. Most of your PCB details will now be automatically selected, leaving you to only select the solder mask and silk-screen colour, as well as to remove the order number or not. You can of course fine-tune everything exactly as you want as well.

7) You can also select whether you want an SMD stencil, or have the board assembled after manufacturing. Please note that the assembly service, as well as the cost of your components, ARE NOT included in the initial quoted price. ( The quote will update depending on what options you select ).

8) When you are happy with the options that you have selected, you can click on the Save to Cart Button. From here on, you can go to the top of the screen, click on Cart, make any payment(s) or use any coupons that you have in your account.

Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

ESP-12E Card

A few months ago, I started working on an MCU Card design, which borrows from the idea of a standard desktop PC, in which there are a main-board, MCU and expansion slots, to add and remove peripherals as needed quickly.

The ESP-12E Card is a continuation of that project, with the ultimate goal to have a universal “main-board” that can accept various MCUs and standardised “expansion modules” that perform a specific task.

ESP-12E Card
ESP-12E Card

The PCB

The ESP-12E Card contains the bare minimum components to allow the chip to function. There are no power regulators or USB-to-TTL converters onboard. Code is flashed via an external USB-to-TTL converter, with Flash and Reset buttons on the actual PCB, or available in the 2×20 Pin female header at the bottom of the card.

Most of the GPIO is also broken out to the 2×20 pin header, with the exception of the 6 GPIO that is usually connected to the internal Flash on the ESP-12E module.

I have made provision for enough power and ground pins on the header as well.

As far as GPIO is concerned, They have been grouped together by function, as much as possible at least, to make interfacing with the base-board as easy as possible.

The Schematic

ESP-12E Card Schematic

The schematic is not complicated. It is a standard ESP-8266 configuration, with all non-essential components removed.

The “base-board” ( a sneak preview )

Sneak preview of the Base Card

In a future article, I will tell you more about this ( for the time being limited to I2C ) base card. [ a quick explanation: When I mean limited to I2C, it relates to the fact that at the moment, the base card, ( a prototype ) can only communicate back to the MCU via I2C protocol from each of the expansion slots, as well as via two dedicated IRQ lines from each slot ]Power is supplied via a small SMPS module.

Manufacturing the PCB


Over the past eight years, PCBWay has continuously upgraded their MANUFACTURING plants and equipment to meet higher quality requirements, and now THEY also provide OEM services to build your products from ideas to mass production and access to the market.


The PCB for this project has been manufactured at PCBWay.
Please consider supporting them if you would like your own copy of this PCB, or if you have any PCB of your own that you need to have manufactured.

PCBWay

If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
1) Click on this link
2) Create an account if you have not already got one of your own.
If you use the link above, you will also instantly receive a $5 USD coupon, which you can use on your first or any other order later. (Disclaimer: I will earn a small referral fee from PCBWay. This referral fee will not affect the cost of your order, nor will you pay any part thereof.)
3) Once you have gone to their website, and created an account, or login with your existing account,

4) Click on PCB Instant Quote

5) If you do not have any very special requirements for your PCB, click on Quick-order PCB

6) Click on Add Gerber File, and select your Gerber file(s) from your computer. Most of your PCB details will now be automatically selected, leaving you to only select the solder mask and silk-screen colour, as well as to remove the order number or not. You can of course fine-tune everything exactly as you want as well.

7) You can also select whether you want an SMD stencil, or have the board assembled after manufacturing. Please note that the assembly service, as well as the cost of your components, ARE NOT included in the initial quoted price. ( The quote will update depending on what options you select ).

8) When you are happy with the options that you have selected, you can click on the Save to Cart Button. From here on, you can go to the top of the screen, click on Cart, make any payment(s) or use any coupons that you have in your account.

Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

Easy to use CAN-BUS Module with Relay, LiPo Battery Backup

Can Relay Module running on battery power

CAN-Bus allows us to add a lot of devices to a single bus (theoretically up to 127, with a practical limit of about 110). It was logical to decide to use CAN-BUS for communication between my LoRa-CAN Module and remote nodes in my ongoing farm telemetry system. In a previous project, I introduced the LoRa-CAN Gateway, which will be used to send/receive messages from the master control unit, the SX127x-RA-02-Module.

Today, I will focus on the design of the node device, an Arduino compatible CAN Relay Module PCB, with a built-in, CAN Controller and Transceiver ( MCP2515 and TJA1050 ), and the option to be powered from a LiPo battery (18650 or Single 3.7v Lipo cell), with charging provided by an MH-CD42 Module, similar to that used in the SX128x project mentioned above. The Module can also be powered directly from up to 12v DC by placing Jumper H2 in the V-REG position…

As mentioned in a previous project, the MH-CD42 module can provide up to 2A of current to charge a battery and provide 5V DC on a direct bypass circuit to power the rest of the circuit while the battery is being charged. This feature makes it ideal for my intended use, as I would only be needing battery power at night when the off-grid solar powered inverter is not actively charging the main batteries, and providing 220v AC.

Can Relay Module Top view

The CAN Relay Module PCB was designed to be as compact as possible, with a total footprint of the standard Arduino UNO. As space was at a premium, and to ensure that there are the absolute minimum additional components that will consume power when operating from the battery, I have not included any USB-to-Serial converters onboard. Firmware can be uploaded with an AVRASp, USBASP, Arduino as ISP or even an external USB-to-Serial converter ( providing that you load a bootloader into the Atmega Chip).

Can Relay Module side view

All of the unused GPIO pins on the ATMEGA chip is broken out into headers, with the exception of D10 ( which is used as CE/SS on the MCP2515 CAN controller), D9 which is connected to the Interrupt from the MCP2515, and D4, which is used to control the onboard Relay.

Can Relay Module with LiPo cell and MH-CD42 Module

The MH-CD42 Module, and LiPo or 18650 Battery are completely optional, The device can function without these, by moving the H2 jumper to the VREG position as already mentioned above. This will divert the DC Voltage(Up to 12v) from the DC input adapter to the build-in 5v LDO voltage regulator to power the device.

If you place the H2 Jumper in the VBAT position, you need to install the MH-CD42 module to provide power to the rest of the PCB, as well as keep the LiPo battery or 18650 Cell charged…

Please NOTE:

When the MH-CD42 module is in use, the total DC input voltage through the DC input adapter SHOULD NOT exceed 5.5v DC! This is a limitation in the operating parameters of the MH-CD42 module. Not paying attention to this will result in damage to the MH-CD42 Module.

You could also power the module with REGULATED 5v DC, directly from any 5v header pin. Please note that in this case,

1) The battery won’t be charged.

2) The LDO regulator will not be in operation.

The Microcontroller

The CAN Relay Module can use any of the ATMEGA8a/88/168/328 AVR microcontrollers, as the pinout is identical. I believe this is an advantage, especially with the current chip prices, where my last quote for an ATMEGA328P-AU was 69$USD!!!! This is in comparison to the 4 to 5 USD each for an ATMEGA8a or ATMEGA168 ( We must also remember though that the 328p is very well known, and thus have higher demand. The 8a/88 or 168 are less well known, have much less memory and flash area, and will thus be cheaper. A word of action though, I had strange issues with I2C on the Atmega8a with Mini core, to such an extent that I2C does not work at all?

If you plan to use I2C on this board, install a 328p right from the start, and save yourself a lot of headaches!

Can Relay Module Schematic Page 1

This is the Relay driver circuit. As you can see, it is optically isolated, and active LOW. This means that you have to pull D4 LOW to energise the relay. Also note that, although the relay is optically isolated from the microcontroller, the coil is NOT galvanically ISOLATED. The load, which is magnetically switched, will be truly galvanically isolated, providing of course that you don’t do something silly like using a common ground to the PCB as a common on the relay…

Can Relay Module Schematic Page 2

This is the Processor and Power-supply schematic. The circuit is basically a standard Arduino Nano, with modifications for the CAN Controller on the next schematic page. Note that the MH-CD42 is not shown on the schematic. The VBAT net connects directly to the VIN pin on the unit, with the BAT net connecting to the positive of the battery. VOUt-5v from the module goes directly to the 5v net. All grounds are commoned.

This is the CAN Controller and Transceiver circuitry. The MCP2515 connects directly to the SPI bus on the microcontroller via D13, D12 and D11, with D10 as CE/SS and D9 as Interrupt or IRQ. It is important to note that although the MCP2515 is a 3v capable device, the TJA1050 Can transceiver is 5v only. This prevents us from running the PCB at 3v unless, of course, we change the TJA1050 out for a 3v capable device…

CODE

The board has been extensively tested with Cory J Fowler’s mcp_can Arduino Library. It works very well indeed.

As I am currently working on the final integration of the two modules, I am not yet ready to publish my final code, showing the operation between the CAN-Bus and LoRa-to-CAN Gateway device in this post. Once I am happy that all issues are definitively sorted out, I will publish my code.

This PCB was manufactured at PCBWAY. The Gerber files and BOM, as well as all the schematics, will soon be available as a shared project on their website. If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
1) Click on this link
2) Create an account if you have not already got one of your own.
If you use the link above, you will also instantly receive a $5USD coupon, which you can use on your first or any other order later. (Disclaimer: I will earn a small referral fee from PCBWay. This referral fee will not affect the cost of your order, nor will you pay any part thereof.)
3) Once you have gone to their website, and created an account, or login with your existing account,

4) Click on PCB Instant Quote

5) If you do not have any very special requirements for your PCB, click on Quick-order PCB

6) Click on Add Gerber File, and select your Gerber file(s) from your computer. Most of your PCB details will now be automatically selected, leaving you to only select the solder mask and silk-screen colour, as well as to remove the order number or not. You can of course fine-tune everything exactly as you want as well.

7) You can also select whether you want an SMD stencil, or have the board assembled after manufacturing. Please note that the assembly service, as well as the cost of your components, ARE NOT included in the initial quoted price. ( The quote will update depending on what options you select ).

8) When you are happy with the options that you have selected, you can click on the Save to Cart Button. From here on, you can go to the top of the screen, click on Cart, make any payment(s) or use any coupons that you have in your account.

Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

CAN-to-LoRa gateway using RA-02, MCP2515 and ATMEGA328P

ATMEGA328P Module with integrated LoRa and CAN-BUS

INTRODUCTION

In my quest to perfect my LoRa telemetry system, I have gone through quite a few prototypes by this time. This post will focus on the next node design. Due to the fact that the area where I will deploy the system is quite large, but with roughly square boundary fence-lines, I decided to try and reduce the number of LoRa Radio nodes needed to cover the entire area. This opened up the opportunity to utilise CAN-BUS to attach sensor-only nodes to a Radio node and have them report status on exception as well as on requests from the radio node.

The device will thus function as a LoRa-to-CAN-BUS Gateway, with some local automation to control the transmission of data to the master station. This concept can also be adapted for use in other areas, such as home -automation, or an industrial setting.

At the heart of the device, I have stuck with the versatile ATMEGA328P, which, current chip shortages excluded, and current high prices excluded, are a very inexpensive chip, with lots of well-tested libraries, and a relatively low learning curve, largely due to its very wide use in the Arduino ecosystem.

The LoRa component is handled by the RA-02 or even RA-01H module, from AI-Tinker (not sponsored). This device, as we have seen in the previous prototypes, requires the use of logic level converters, due to the fact that it only accepts 3.3v logic levels. While I could get rid of those if I powered the ATMEGA328P from 3.3v, it would give rise to two problems, of which one will still force the use of level converters…

I chose to run the ATMEGA328P at 16Mhz, which basically forces me to use 5v to power the chip. The second reason is not so obvious unless you read a few datasheets very thoroughly…

The CAN-Bus component is handled by the MCP2515 Standalone SPI-to-CAN Controller, as well as the TJA1050 CAN Bus transceiver.

This is where things get interesting… The MCP2515 can operate on 3.3v, but the TJA1050 is a 5v only device. I could thus in theory use logic level converters only between the MCP2515 and the TJA1050, while running the rest of the circuit on 3.3v…

Given that I would rather run the ATMEGA328P on 16Mhz, as well as the fact that my LoRa Radio Module circuit, with its logic level converter circuitry, works extremely well, I decided not to change that, and keep the CAN Bus running at 5v all the way through, as I would still have to use a 5v regulator on the PCB anyway just for that purpose.

IO connections for LoRa and CAN BUS modules

You can order this PCB directly from PCBWay, by clicking here

Both of the two integrated components ( Lora and CAN ) are SPI devices. This means that they share common SCK, MISO and MOSI lines ( provided on the ATMEGA328P by pins D13, D12 and D11 respectively. The individual SPI device is then further selected for operation by the use of a CE pin, one unique pin per device, which is pulled low by the MCU to indicate to the device that it should pay attention to the data being transmitted on the SPI bus…

Both LoRa and CAN makes use of other pins as well, LoRa needs a Reset pin, connected to D9, a CS/CE Pin on D10 as well as a hardware interrupt pin, connected to D2. ( Note that this is for use with Sandeep Mistry’s LoRa Library. The Radiolib library would require an additional pin, usually connected to DIO1 on the LoRa module. The device does not provide access to those pins in its current layout, so you can only use it with the Sandeep Mistry library, for now at least… )

The CAN module uses a CE/CS pin at D4, with an IRQ pin on D6, which, although not a hardware interrupt pin, does have PCINT functionality.

Pins D10, D9 and D2 are not broken out for user access. although I decided to give access to D4 and D6, as well as the SPI bus, D11, D12, D13, to allow interfacing with logic analysers, or adding other SPI devices to the bus…

This brings us to a very interesting point… Does the two SPI devices actually play nice together? and what do I mean by “playing nice together”?

To answer that question, we are forced to first look at a bit of theory, as well as understand the fundamental differences between SPI and I2C…

The Difference between SPI and I2C

Most of us will be quite familiar with I2C, as it is a very common protocol used to connect sensors to a microcontroller. It consists of only two IO lines, SDA for data, and SCL for the clock. Each device on the bus has its own built-in address, like in the case of a PCF8574 IO expander, this address can be selectable between 0x20h and 0x27h. All of the devices share these common data lines, and will only respond when specifically addressed by the master controller… Unless you accidentally put two devices with the same address on the same bus, (if that would even work), there is no way that the wrong device would respond to any request for data…

SPI on the other hand, operates on a completely different principle, making it quite a few times faster than I2c, with data being simultaneously sent and received by the active device… SPI is also known as a four-wire protocol. Each device has a minimum of 4 data lines, namely SCK ( clock), MOSI ( for data transmitted FROM the Master TO the slave device ), MISO ( for data transmitted TO the master FROM the slave device) and a CE or CS ( Chip select ) pin.

SCK, MISO and MOSI are COMMON to all devices, meaning it is shared between all of them. CE/CS is a unique pin for EACH device, meaning that if you had four SPI devices on a bus, you would have to have four individual CE/CS pins!

A device will, or rather should only respond to data on the SPI-BUS IF the master pulls its respective CE/CS pin LOW. It should now very quickly become clear to you that this can become a very very complex mess, very quickly.

Let us take a very good example. the ST7789 SPI display module, has a cheap version, commonly sold on Ali-express, as we ll as other online stores. This particular module, I assume in a bid to make it easier to use, has the CE/CS pin internally pulled down to ground by default… So what about that, you may ask? What is wrong with that, as it saves you an IO pin?

It is in fact very wrong, a fact that you will very quickly discover if you ever tried using one of those displays on an SPI bus together with other SPI devices… Nothing will work, or only the display will work ( if you are lucky)

But why?

Pulling CE/CS LOW, signals to the chip that it should respond to instructions on the common SCK, MISO and MOSI lines. having the pin internally pulled LOW, thus forces that chip to always respond, even when it should not. Thus contaminating the entire SPI-BUS with garbage…

The answer to the question

After that very long-winded explanation, which is still extremely basic, it is time that we get back to our original question:

Does the Sx127x ( RA-02 ) Module and the MCP2515 Can Controller play nice on the same bus? The answer is not straightforward, as it comes down to which libraries you use…

Remember that the library must pull down the CE/CS pin of the device that it wants to communicate with. Some libraries wrongly assume that they are the only ones in use, and ignores the simple fact, that they should release the CE/CS pin AFTER EVERY transaction, to free up the bus for other devices to use it as well…

After extensive testing, I can however say that Sandeep Mistry’s LoRa Library, as well as the mcp_can library, does indeed play nice together. These two libraries do not keep the individual CE/CS pins pulled LOW, and allows the spi bus to be shared.

This is not the case with the ST7789 Module discussed above, where the hardware actually pulls the pin ow the entire time…

Taking a closer look at the PCB

Let us take a closer look at the PCB. The Ra-02 Module ( LoRa ) dominates most of the left-hand side of the PCB, with the ATMEGA328P on its right. The RA-02 is surrounded by the level converters, using the BSS138 N-Channel Mosfet, and 10k resistors (Q1 to Q6, R1, R2, R3, R4, R5, R6, R8, R9, R10, R11, R12, R13)

C1 and C2 are bypass capacitors for the Ra-02 module

In the bottom left corner, we have a hardware reset button, to reset the ATMEGA328P, with a yellow jumper (H1) next to it. This jumper controls the 120ohm ballast resistor (R17) for the CAN bus. Removing the jumper will remove the ballast. Directly below that is the CAN connecter, marked as U5, with CH as CAN-H, and CL as CAN-L ports.

U3 and U4, together with R18, R19, X2, C16, C17 make up the CAN components on the PCB. Decoupling is provided by C6, C7, C8 as well as C9 and C12 ( Includes the ATMEGA328P’s decoupling as well )

An ICSP programming header is provided above U1 ( ATMEGA328P) for use with USPASP, AVRASP or Arduino as ISP and similar.

No USB to serial converter is provided on the board, Serial upload is possible is loaded with an Arduino bootloader for the Arduino NANO ( to make use of all the analog inputs). RxD, TxD and DTR pins are broken out on opposite sides of the PCB, as well as access to 3.3v, 5v and GND pins.

A DC power socket is provided. it can accept up to 12v DC, although I would recommend not to go over 7.2 volts, to not stress the LDO regulators, at the back of the PCB ( LDO1, and LDO2) too much.

You can order this PCB directly from PCBWay, by Clicking here

in the picture above, I have connected a USB-to Serial converter, as well as CAN-BUS to the device.

Schematic Diagram

The detailed schematic diagrams are provided below:

Sheet 1 (above) takes care of the ATMEGA328p and it supporting circuitry, as well as the power supply via LDO regulators.

Sheet 2 (below) takes care of the Logic Level converters, RA-02 (Sx1278) LoRa Module, and CAN-BUS controller and transceiver circuitry.

Software and Firmware

In order to test this module, I made use of the mcp_can library by Cory J Fowler, for the CAN-Bus part,

as well as Arduino-LoRa by Sandeep Mistry

A combined example utilising both LoRa and CAN at the same time, will be released with the next part of the project, namely the CAN-Relay Module

This PCB was manufactured at PCBWAY. The Gerber files and BOM, as well as all the schematics, will soon be available as a shared project on their website. If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
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Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

Port Extender Card for the MCU-8266-12E

Port Extender Card for the MCU-8266-12E IoT Controller

Introduction

After quite a few experiments, and playing with a lot of ideas, we have finally produced and tested an almost final prototype for the MCU-8266-12E IoT Controller Port Extender Card. While the baseboard already has quite a lot of free GPIO pins for additional sensors and devices, It did however have quite a few issues, namely a lack of sufficient Power outputs, difficulty access to the I2C bus, as well as only 2 relay outputs. Granted that you do have access to unused pins on the PCF8574 Port Extender, We nonetheless decided that an add-on card would definitely make sense to allow this device to really be more useable.

While looking at various ideas for this card, the most flexible seemed to be the APE Protocol device as documented in ESPHome. They used a standard Arduino board for that, but we decided that, after testing it with an Arduino Nano, since it seems to work well, let us just design a dedicated PCB. It also looks much better as well 🙂

Some Features (Aside from being a fully functional Arduino clone as well)

1). Dedicated LDO Regulators for 5v and 3.3v (800mA each), with jumpers to switch them on or off (receive power only from the IoT Motherboard).
2.) Dedicated Logic Level Converter on the I2C Bus ( This is sort of very much needed 🙂 The Atmega 328P-AU is running at 5v on this device, to enable it to run at 16Mhz.. and the ESP8266 on the Motherboard is a 3.3v device..

There are also 3x 3.3V I2C Headers, complete with 3.3v and Ground, as well as a single 5v I2C header
3). 8 Analog Inputs ( While practically you can only use 6 of these if you use I2C )
4). Voltage Divider provided on A0 to measure VIN ( to be safe, we calculated the resistors for 22v)
5). 100R current limiting resistor on A1 and A2, to measure 5v and 3.3v as well…
Analog inputs A0, A1 and A2 can be switched back to normal operation by changing the jumper at J2,J3 or J4 from On to Off.
6). 12 Digital Inputs/Outputs (14 if you use D0 and D1 as well), as well as a Jumper to remove the LED on D13.
7). Full access to the PCF8574 and ESP8266 Pins from the motherboard below.

Pictures of the PCB

Circuit Diagram

ATMega328P-AU Circuit diagram with LDO Regulators, headers and supporting circuitry.
Analog measuring circuitry, level converters and supporting circuitry and headers

Uploading Code to the ATMega328P

Uploading code to the device requires the use of either an ISCP programmer ( Arduino as ISP works well ) or in the case of a pre-boot loaded chip, a USB-to-Serial converter. We did not find it necessary to add a dedicated USB-to-Serial converter onto the PCB. It is quite easy enough to do any flashing with the tools mentioned above.


Make sure that the PCB is not stacked when doing this. ( This will prevent excessive current use of other components when you supply 5v to the PE card.


Procedure to upload using ICSP

During assembly, you are required to solder a single 90-degree bend pin header on the bottom side of the PCB, in the same hole as the board side edge of the RESET push-button. This will serve as the RESET Pin for the ISCP. Other connections are as follows:

H2 Header <- > ICSP Programmer
MOSI (E11~) – MOSI ( or Pin 11 on Arduino as ISP )
MISO (E12 ) – MISO ( or Pin 12 on Arduino as ISP )
SCK (E13) – D13 (or Pin 13 on Arduino as ISP )
RESET – D10 (or Pin 10 on Arduino as ISP )

5v and Ground from Arduino as ISP or ISCP Programmer to any 5v and ground pin on the PE Card

Please note the description above for assembly of the RESET pin header



Procedure to upload using USB-to-Serial converter

H1 Header

E0/Rx <- to Tx of USB-to-Serial converter
E1/Tx -> to Rx of USB-to-Serial converter

H2 Header

DTR <-> to DTR of USB-to-Serial converter [ This connection is needed for successful uploading. Don’t leave it out ]


5v and Ground from the USB-to-Serial converter to any 5v and ground pin on the PE Card


Testing with ESPHome APE protocol and the MCU-8266-12E IoT controller

The following Arduino Sketch needs to be uploaded to the device.
It will allow the device to function as a custom I2C device. Feel free to change the I2C address in the sketch as you choose, but remember to use the same address in your ESPHome YAML configuration file

/*
Ports:
  0 0 .. 13 13
  A0: 14, A1: 15, A2: 16, A3: 17: A4: 18: A5: 19: A6: 20, A7: 21
  port bits: 5 ... 0..32
  0:   0: 00000
  1:   1: 00001
  A7: 21: 10101
*/

#include <Arduino.h>
#include <Wire.h>

//#define DEBUG // remove debug so pin 0 and 1 can be used for IO

#define I2C_ADDRESS 8

void onRequest();
void onReceive(int);

void setup()
{
#ifdef DEBUG
  Serial.begin(115200);
  Serial.println(F("Init "));
#endif

  analogReference(INTERNAL);

  Wire.begin(I2C_ADDRESS);
  Wire.onRequest(onRequest);
  Wire.onReceive(onReceive);

#ifdef DEBUG
  Serial.println(F("Wire ok"));
#endif
}

void loop()
{
  //int temp = analogRead(A1);
  //Serial.println(temp);
}

volatile byte buffer[3];
volatile byte len = 1;

#define DIGITAL_READ(b, pin, mask) \
  if (digitalRead(pin))            \
    buffer[b] |= mask;

void readDigital()
{
  len = 3;
  buffer[0] = 0;
  DIGITAL_READ(0, 0, 1);
  DIGITAL_READ(0, 1, 2);
  DIGITAL_READ(0, 2, 4);
  DIGITAL_READ(0, 3, 8);
  DIGITAL_READ(0, 4, 16);
  DIGITAL_READ(0, 5, 32);
  DIGITAL_READ(0, 6, 64);
  DIGITAL_READ(0, 7, 128);

  buffer[1] = 0;
  DIGITAL_READ(1, 8, 1);
  DIGITAL_READ(1, 9, 2);
  DIGITAL_READ(1, 10, 4);
  DIGITAL_READ(1, 11, 8);
  DIGITAL_READ(1, 12, 16);
  DIGITAL_READ(1, 13, 32);
  DIGITAL_READ(1, A0, 64);
  DIGITAL_READ(1, A1, 128);

  buffer[2] = 0;
  DIGITAL_READ(2, A2, 1);
  DIGITAL_READ(2, A3, 2);

// I2C
//DIGITAL_READ(2, A4, 4);
//DIGITAL_READ(2, A5, 8);

// DIGITAL READ not supports on A3 .. A7
#ifdef DEBUG_READ
  Serial.print(F("Read 3 bytes: "));
  Serial.print(buffer[0]);
  Serial.print(' ');
  Serial.print(buffer[1]);
  Serial.print(' ');
  Serial.println(buffer[2]);

#endif
}
void readAnalog(int pin)
{
  int val = analogRead(A0 + pin);
  len = 2;
  buffer[0] = val & 0xFF;
  buffer[1] = (val >> 8) & 0b11;
#ifdef DEBUG_READ
  Serial.print(F("Read analog pin "));
  Serial.println(pin);
#endif
}

void onRequest()
{
  Wire.write(const_cast<uint8_t *>(buffer), len);
}

#define CMD_DIGITAL_READ 0x0

#define CMD_WRITE_ANALOG 0x2
#define CMD_WRITE_DIGITAL_HIGH 0x3
#define CMD_WRITE_DIGITAL_LOW 0x4

#define CMD_SETUP_PIN_OUTPUT 0x5
#define CMD_SETUP_PIN_INPUT_PULLUP 0x6
#define CMD_SETUP_PIN_INPUT 0x7

// 8 analog registers.. A0 to A7
// A4 and A5 not supported due to I2C
#define CMD_ANALOG_READ_A0 0b1000 // 0x8
// ....
#define CMD_ANALOG_READ_A7 0b1111 // 0xF

#define CMD_SETUP_ANALOG_INTERNAL 0x10
#define CMD_SETUP_ANALOG_DEFAULT 0x11

void onReceive(int numBytes)
{
#ifdef DEBUG_READ
  Serial.print("Received bytes: ");
  Serial.println(numBytes);
#endif
  int cmd = Wire.read();

  switch (cmd)
  {
  case CMD_DIGITAL_READ:
    readDigital();
    break;
  }

  if (cmd >= CMD_ANALOG_READ_A0 && cmd <= CMD_ANALOG_READ_A7)
  {
    readAnalog(cmd & 0b111);
    return;
  }

  int pin = Wire.read();

  switch (cmd)
  {
  case CMD_WRITE_DIGITAL_HIGH:
  case CMD_WRITE_DIGITAL_LOW:
  {
    bool output = cmd == CMD_WRITE_DIGITAL_HIGH;
    digitalWrite(pin, output);
#ifdef DEBUG
    Serial.print(F("Pin "));
    Serial.print(pin);
    Serial.println(output ? F(" HIGH") : F(" LOW"));
#endif
    break;
  }
  case CMD_WRITE_ANALOG:
  {
    int val = Wire.read() & (Wire.read() << 8);
    analogWrite(pin, val);
#ifdef DEBUG
    Serial.print(F("Pin "));
    Serial.print(pin);
    Serial.print(F(" Analog write "));
    Serial.println(val);
#endif
    break;
  }
  case CMD_SETUP_PIN_OUTPUT:
    pinMode(pin, OUTPUT);
#ifdef DEBUG
    Serial.print(F("Pin "));
    Serial.print(pin);
    Serial.println(F(" OUTPUT"));
#endif
    break;
  case CMD_SETUP_PIN_INPUT:
    pinMode(pin, INPUT);
#ifdef DEBUG
    Serial.print(F("Pin "));
    Serial.print(pin);
    Serial.println(F("INPUT"));
#endif
    break;
  case CMD_SETUP_PIN_INPUT_PULLUP:
    pinMode(pin, INPUT_PULLUP);
#ifdef DEBUG
    Serial.print(F("Pin "));
    Serial.print(pin);
    Serial.println(F("INPUT PULLUP"));
#endif
    break;
  case CMD_SETUP_ANALOG_INTERNAL:
    analogReference(INTERNAL);
#ifdef DEBUG
    Serial.println(F("Analog reference INTERNAL"));
#endif
    break;
  case CMD_SETUP_ANALOG_DEFAULT:
    analogReference(DEFAULT);
#ifdef DEBUG
    Serial.println(F("Analog reference DEFAULT"));
#endif
    break;
  }
}

The following C header file needs to be uploaded to your Home Assistant ESPHome folder.

// Must disable logging if using logging in main.cpp or in other custom components for the
//  __c causes a section type conflict with __c thingy
// you can enable logging and use it if you enable this in logger:
/*
logger:
  level: DEBUG
  esp8266_store_log_strings_in_flash: False
  */

//#define APE_LOGGING

// take advantage of LOG_ defines to decide which code to include
#ifdef LOG_BINARY_OUTPUT
#define APE_BINARY_OUTPUT
#endif
#ifdef LOG_BINARY_SENSOR
#define APE_BINARY_SENSOR
#endif
#ifdef LOG_SENSOR
#define APE_SENSOR
#endif

static const char *TAGape = "ape";

#define APE_CMD_DIGITAL_READ 0
#define APE_CMD_WRITE_ANALOG 2
#define APE_CMD_WRITE_DIGITAL_HIGH 3
#define APE_CMD_WRITE_DIGITAL_LOW 4
#define APE_CMD_SETUP_PIN_OUTPUT 5
#define APE_CMD_SETUP_PIN_INPUT_PULLUP 6
#define APE_CMD_SETUP_PIN_INPUT 7
// 8 analog registers.. A0 to A7
// A4 and A5 not supported due to I2C
#define CMD_ANALOG_READ_A0 0b1000 // 0x8
// ....
#define CMD_ANALOG_READ_A7 0b1111 // 0xF

#define CMD_SETUP_ANALOG_INTERNAL 0x10
#define CMD_SETUP_ANALOG_DEFAULT 0x11

#define get_ape(constructor) static_cast<ArduinoPortExpander *>(constructor.get_component(0))

#define ape_binary_output(ape, pin) get_ape(ape)->get_binary_output(pin)
#define ape_binary_sensor(ape, pin) get_ape(ape)->get_binary_sensor(pin)
#define ape_analog_input(ape, pin) get_ape(ape)->get_analog_input(pin)

class ArduinoPortExpander;

using namespace esphome;

#ifdef APE_BINARY_OUTPUT
class ApeBinaryOutput : public output::BinaryOutput
{
public:
  ApeBinaryOutput(ArduinoPortExpander *parent, uint8_t pin)
  {
    this->parent_ = parent;
    this->pin_ = pin;
  }
  void write_state(bool state) override;
  uint8_t get_pin() { return this->pin_; }

protected:
  ArduinoPortExpander *parent_;
  uint8_t pin_;
  // Pins are setup as output after the state is written, Arduino has no open drain outputs, after setting an output it will either sink or source thus activating outputs writen to false during a flick.
  bool setup_{true};
  bool state_{false};

  friend class ArduinoPortExpander;
};
#endif

#ifdef APE_BINARY_SENSOR
class ApeBinarySensor : public binary_sensor::BinarySensor
{
public:
  ApeBinarySensor(ArduinoPortExpander *parent, uint8_t pin)
  {
    this->pin_ = pin;
  }
  uint8_t get_pin() { return this->pin_; }

protected:
  uint8_t pin_;
};
#endif

#ifdef APE_SENSOR
class ApeAnalogInput : public sensor::Sensor
{
public:
  ApeAnalogInput(ArduinoPortExpander *parent, uint8_t pin)
  {
    this->pin_ = pin;
  }
  uint8_t get_pin() { return this->pin_; }

protected:
  uint8_t pin_;
};
#endif

class ArduinoPortExpander : public Component, public I2CDevice
{
public:
  ArduinoPortExpander(I2CBus *bus, uint8_t address, bool vref_default = false)
  {
    set_i2c_address(address);
    set_i2c_bus(bus);
    this->vref_default_ = vref_default;
  }
  void setup() override
  {
#ifdef APE_LOGGING
    ESP_LOGCONFIG(TAGape, "Setting up ArduinoPortExpander at %#02x ...", address_);
#endif

    /* We cannot setup as usual as arduino boots later than esp8266
            Poll i2c bus for our Arduino for a n seconds instead of failing fast,
            also this is important as pin setup (INPUT_PULLUP, OUTPUT it's done once)
        */
    this->configure_timeout_ = millis() + 5000;
  }
  void loop() override
  {
    if (millis() < this->configure_timeout_)
    {
      bool try_configure = millis() % 100 > 50;
      if (try_configure == this->configure_)
        return;
      this->configure_ = try_configure;

      if (ERROR_OK == this->read_register(APE_CMD_DIGITAL_READ, const_cast<uint8_t *>(this->read_buffer_), 3))
      {
#ifdef APE_LOGGING
        ESP_LOGCONFIG(TAGape, "ArduinoPortExpander found at %#02x", address_);
#endif
        delay(10);
        if (this->vref_default_)
        {
          this->write_register(CMD_SETUP_ANALOG_DEFAULT, nullptr, 0); // 0: unused
        }

        // Config success
        this->configure_timeout_ = 0;
        this->status_clear_error();
#ifdef APE_BINARY_SENSOR
        for (ApeBinarySensor *pin : this->input_pins_)
        {
          App.feed_wdt();
          uint8_t pinNo = pin->get_pin();
#ifdef APE_LOGGING
          ESP_LOGCONFIG(TAGape, "Setup input pin %d", pinNo);
#endif
          this->write_register(APE_CMD_SETUP_PIN_INPUT_PULLUP, &pinNo, 1);
          delay(20);
        }
#endif
#ifdef APE_BINARY_OUTPUT
        for (ApeBinaryOutput *output : this->output_pins_)
        {
          if (!output->setup_)
          { // this output has a valid value already
            this->write_state(output->pin_, output->state_, true);
            App.feed_wdt();
            delay(20);
          }
        }
#endif
#ifdef APE_SENSOR
        for (ApeAnalogInput *sensor : this->analog_pins_)
        {
          App.feed_wdt();
          uint8_t pinNo = sensor->get_pin();
#ifdef APE_LOGGING
          ESP_LOGCONFIG(TAGape, "Setup analog input pin %d", pinNo);
#endif
          this->write_register(APE_CMD_SETUP_PIN_INPUT, &pinNo, 1);
          delay(20);
        }
#endif
        return;
      }
      // Still not answering
      return;
    }
    if (this->configure_timeout_ != 0 && millis() > this->configure_timeout_)
    {
#ifdef APE_LOGGING
      ESP_LOGE(TAGape, "ArduinoPortExpander NOT found at %#02x", address_);
#endif
      this->mark_failed();
      return;
    }

#ifdef APE_BINARY_SENSOR
    if (ERROR_OK != this->read_register(APE_CMD_DIGITAL_READ, const_cast<uint8_t *>(this->read_buffer_), 3))
    {
#ifdef APE_LOGGING
      ESP_LOGE(TAGape, "Error reading. Reconfiguring pending.");
#endif
      this->status_set_error();
      this->configure_timeout_ = millis() + 5000;
      return;
    }
    for (ApeBinarySensor *pin : this->input_pins_)
    {
      uint8_t pinNo = pin->get_pin();

      uint8_t bit = pinNo % 8;
      uint8_t value = pinNo < 8 ? this->read_buffer_[0] : pinNo < 16 ? this->read_buffer_[1] : this->read_buffer_[2];
      bool ret = value & (1 << bit);
      if (this->initial_state_)
        pin->publish_initial_state(ret);
      else
        pin->publish_state(ret);
    }
#endif
#ifdef APE_SENSOR
    for (ApeAnalogInput *pin : this->analog_pins_)
    {
      uint8_t pinNo = pin->get_pin();
      pin->publish_state(analogRead(pinNo));
    }
#endif
    this->initial_state_ = false;
  }

#ifdef APE_SENSOR
  uint16_t analogRead(uint8_t pin)
  {
    bool ok = (ERROR_OK == this->read_register((uint8_t)(CMD_ANALOG_READ_A0 + pin), const_cast<uint8_t *>(this->read_buffer_), 2));
#ifdef APE_LOGGING
    ESP_LOGVV(TAGape, "analog read pin: %d ok: %d byte0: %d byte1: %d", pin, ok, this->read_buffer_[0], this->read_buffer_[1]);
#endif
    uint16_t value = this->read_buffer_[0] | ((uint16_t)this->read_buffer_[1] << 8);
    return value;
  }
#endif

#ifdef APE_BINARY_OUTPUT
  output::BinaryOutput *get_binary_output(uint8_t pin)
  {
    ApeBinaryOutput *output = new ApeBinaryOutput(this, pin);
    output_pins_.push_back(output);
    return output;
  }
#endif
#ifdef APE_BINARY_SENSOR
  binary_sensor::BinarySensor *get_binary_sensor(uint8_t pin)
  {
    ApeBinarySensor *binarySensor = new ApeBinarySensor(this, pin);
    input_pins_.push_back(binarySensor);
    return binarySensor;
  }
#endif
#ifdef APE_SENSOR
  sensor::Sensor *get_analog_input(uint8_t pin)
  {
    ApeAnalogInput *input = new ApeAnalogInput(this, pin);
    analog_pins_.push_back(input);
    return input;
  }
#endif
  void write_state(uint8_t pin, bool state, bool setup = false)
  {
    if (this->configure_timeout_ != 0)
      return;
#ifdef APE_LOGGING
    ESP_LOGD(TAGape, "Writing %d to pin %d", state, pin);
#endif
    this->write_register(state ? APE_CMD_WRITE_DIGITAL_HIGH : APE_CMD_WRITE_DIGITAL_LOW, &pin, 1);
    if (setup)
    {
      App.feed_wdt();
      delay(20);
#ifdef APE_LOGGING
      ESP_LOGI(TAGape, "Setup output pin %d", pin);
#endif
      this->write_register(APE_CMD_SETUP_PIN_OUTPUT, &pin, 1);
    }
  }

protected:
  bool configure_{true};
  bool initial_state_{true};
  uint8_t read_buffer_[3]{0, 0, 0};
  unsigned long configure_timeout_{5000};
  bool vref_default_{false};

#ifdef APE_BINARY_OUTPUT
  std::vector<ApeBinaryOutput *> output_pins_;
#endif
#ifdef APE_BINARY_SENSOR
  std::vector<ApeBinarySensor *> input_pins_;
#endif
#ifdef APE_SENSOR
  std::vector<ApeAnalogInput *> analog_pins_;
#endif
};

#ifdef APE_BINARY_OUTPUT
void ApeBinaryOutput::write_state(bool state)
{
  this->state_ = state;
  this->parent_->write_state(this->pin_, state, this->setup_);
  this->setup_ = false;
}
#endif

The file should be named “arduino_port_expander.h”

Make the following changes to your ESPHome YAML configuration file for the MCU-8266-12E device

esphome:
  name: mcu-8266-12e-01
  platform: ESP8266
  board: nodemcuv2
  includes:
      - arduino_port_expander.h
# Note the include file - This loads the APE Header

# Enable logging
logger:

# Enable Home Assistant API
api:

ota:
  password: "<your password will be different - dont change it>"

wifi:
  ssid: <your ssid>
  password: <your password>

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "MCU-8266-Hotspot"
    password: "password"

captive_portal:

i2c:
# PCB Prototype
  sda: GPIO5
  scl: GPIO4
# PCB Rev 1.5 or higher, comment the above 2 lines
# and uncomment
#sda: GPIO4
#scl: GPIO5
#################### - IMPORTANT ###########
  scan: true
  id: i2c_bus_a
  
pcf8574:
  - id: 'pcf8574_hub'
    address: 0x22 # Set at 0x22, feel free to change to your liking, Remember to set the chip to the address you choose as well
    pcf8575: false

time:
  - platform: sntp
    id: ha_time
    timezone: "Etc/GMT+7"

status_led:
  pin:
    number: GPIO16
    inverted: true

#Define the APE as a custom component, taking care to ensure that:
#1). The I2C Bust ID is the same as the one you have defined in the I2C: Section
#2). The address of the APE is the same as the one you set in the sketch
    
custom_component:
  - id: ape
    lambda: |-
      auto ape_component = new ArduinoPortExpander(i2c_bus_a, 0x08,true);
      return {ape_component};
    

sensor:

  - platform: custom
    lambda: |-
      return {ape_analog_input(ape, 0),  // 1 = A1
             ape_analog_input(ape, 1),
             ape_analog_input(ape, 2)};
   
#We define 3 analog inputs (A0,A1,A2) to monitor voltages on the card
#Note that you MUST define them in the sensors section below as well AND
#THAT THEY MUST BE IN THE SAME SEQUENCE THAT YOU DEFINED THEM IN ABOVE HERE
#
#ALSO NOTE THAT YOU CAN "NOT" use A4 and A5, as they are used for I2C !
#
# As an example, of adding another 3 analog inputs, your definition above will change to:
#
#    return {ape_analog_input(ape, 0),
#           ape_analog_input(ape, 1),
#           ape_analog_input(ape, 2),
#           ape_analog_input(ape, 3),
#           ape_analog_input(ape, 6),
#           ape_analog_input(ape, 7)};
#
#
# Now define the sensors connected to these analogs below:

             
    sensors:
      - name: "PE Card VIN"
        id: analog_a0
        device_class: "voltage"
        unit_of_measurement: "v"
        accuracy_decimals: 2
        filters:
          - lambda: return x * (22.00/1023.0);
          - throttle: 60s

# We use a lambda to scale the value of VIN - Our Voltage divider was designed around 22 volt
# thus we need 22 volt here in the calculation as well to make it accurate
#
      - name: "PE Card 5v"
        id: analog_a1
        device_class: "voltage"
        unit_of_measurement: "v"
        accuracy_decimals: 2
        filters:
          - lambda: return x * (5.02/1023.0); 
          - throttle: 60s
      - name: "PE Card 3v"
        id: analog_a2
        device_class: "voltage"
        unit_of_measurement: "v"
        accuracy_decimals: 2
        filters:
          - lambda: return x * (5.02/1023.0);
          - throttle: 60s
 
# The ATMega328P 's Analog Reference is set to 5v internally, thus we need to also scale the 
# 3v input with a maximum of 5v ... 

# In case you enabled the other 3 Analog Inputs above, you need to add the following
#
#    - name: "Analog 3"
#      id: analog_a3
#      filters:
#        - throttle: 60s
#    - name: "Analog 6"
#      id: analog_a6
#      filters:
#        - throttle: 60s
#    - name: "Analog 7"
#      id: analog_a7
#      filters:
#        - throttle: 60s
#
#
             
             
             
  - platform: adc
    pin: VCC
    name: "ESP8266 Chip Voltage"
    id: mcu_voltage
    unit_of_measurement: "V"
    device_class: "voltage"
    accuracy_decimals: 2
    update_interval: 60s
    
  - platform: wifi_signal
    name: "WiFi Signal Sensor"
    id: wifi_strength
    device_class: "signal_strength"
    unit_of_measurement: "dBm"
    update_interval: 240s
    

#Digital outputs function the same

output:
- platform: custom
  type: binary
  lambda: |-
    return {ape_binary_output(ape, 2),
            ape_binary_output(ape, 3),
            ape_binary_output(ape, 4),
            ape_binary_output(ape, 5),
            ape_binary_output(ape, 6),
            ape_binary_output(ape, 7)};
  outputs:
    - id: ape_output_p2
      inverted: false
    - id: ape_output_p3
      inverted: false
    - id: ape_output_p4
      inverted: false
    - id: ape_output_p5
      inverted: false
    - id: ape_output_p6
      inverted: false
    - id: ape_output_p7
      inverted: false
      
- platform: gpio
  id: relay_1
  pin:
    pcf8574: pcf8574_hub
    number: 0
    mode: OUTPUT
    inverted: true
- platform: gpio
  id: relay_2
  pin:
    pcf8574: pcf8574_hub
    number: 1
    mode: OUTPUT
    inverted: true
- platform: gpio
  id: led_status_1
  pin:
    pcf8574: pcf8574_hub
    number: 2
    mode: OUTPUT
    inverted: true
- platform: gpio
  id: led_status_2
  pin:
    pcf8574: pcf8574_hub
    number: 3
    mode: OUTPUT
    inverted: true
      
binary_sensor:
  - platform: gpio
    id: push_button_1
    name: 'Relay1 Pushbutton'
    device_class: ''
    pin: 
      pcf8574: pcf8574_hub
      number: 4
      mode: INPUT
      inverted: true
    on_press:
      then:
        - switch.toggle: switch_relay1
        
  - platform: gpio
    id: push_button_2
    name: 'Relay2 Pushbutton'
    device_class: ''
    pin:
      pcf8574: pcf8574_hub
      number: 5
      mode: INPUT
      inverted: true
    on_press:
      #min_length: 50ms
      #max_length: 500ms
      then:
        - switch.toggle: switch_relay2
    filters:
        - delayed_on_off: 50ms
      
  

switch:
  - platform: output
    id: switch_relay1
    name: "Relay No. 1 (#0)"
    output: relay_1
    on_turn_on:
      - output.turn_on: led_status_1
    on_turn_off:
      - output.turn_off: led_status_1
      
  - platform: output
    id: switch_relay2
    name: "Relay No. 2 (#1)"
    output: relay_2
    on_turn_on:
      - output.turn_on: led_status_2
    on_turn_off:
      - output.turn_off: led_status_2
  - platform: restart
    id: reboot_switch
    name: "Reboot Me"

Detailed information on the APE is available here

Manufacturing the PCB

This PCB was manufactured at PCBWAY. The Gerber files and BOM, as well as all the schematics, will soon be available as a shared project on their website. If you would like to have PCBWAY manufacture one of your own, designs, or even this particular PCB, you need to do the following…
1) Click on this link
2) Create an account if you have not already got one of your own.
If you use the link above, you will also instantly receive a $5USD coupon, which you can use on your first or any other order later. (Disclaimer: I will earn a small referral fee from PCBWay. This referral fee will not affect the cost of your order, nor will you pay any part thereof.)
3) Once you have gone to their website, and created an account, or login with your existing account,

4) Click on PCB Instant Quote

5) If you do not have any very special requirements for your PCB, click on Quick-order PCB

6) Click on Add Gerber File, and select your Gerber file(s) from your computer. Most of your PCB details will now be automatically selected, leaving you to only select the solder mask and silk-screen colour, as well as to remove the order number or not. You can of course fine-tune everything exactly as you want as well.

7) You can also select whether you want an SMD stencil, or have the board assembled after manufacturing. Please note that the assembly service, as well as the cost of your components, ARE NOT included in the initial quoted price. ( The quote will update depending on what options you select ).

8) When you are happy with the options that you have selected, you can click on the Save to Cart Button. From here on, you can go to the top of the screen, click on Cart, make any payment(s) or use any coupons that you have in your account.

Then just sit back and wait for your new PCB to be delivered to your door via the shipping company that you have selected during checkout.

Taking the next step with the IoT Controller.

With the initial prototyping of my IoT Controller now completed, and software performing as expected, I have started with the development of an add-on shield. The base device offers 2 built-in relays, and access to another 6 IO Ports on the PCF8574, as well as all the GPIO on the ESP-12E. This is all good and well and suits my initial purposes well, but

I do however now see a need to add more sensors to the device, as well as find an elegant way to power it directly from mains power, while not having lots of wires going anywhere.

So the next steps will be:

Design an add-on-shield to provide me with the following:
– Analog inputs.
 The ESP-12E has only one, and that will be very limiting in some situations.
-Digital Inputs and Outputs
 While there are still unused GPIO ports on the existing board, native to the ESP-12E,
 having the ability to connect additional devices and sensors will definitely be a good
 option to have in future.
-Some sort of Display
 Small OLED I2C displays are cheap and easy to use. I can also go full colour with an SPI
 display…

From here on, I have to decide on how and what.
I can go the discreet chip route, by using dedicated I2C chips that provide all these functions, or I can add a secondary micro-controller to the shield, which would provide more flexibility, but can also add complexity to the final design…

Please follow along and join me on the next part of this design journey. I can not promise
anything yet, but I do guarantee that it will be exciting…