In answer to quite a few requests for a prototype shield, similar to my ESP32-S Dev Prototype shield, but for use with the ESP-12E DEV board, I have decided to do a quick design, and make it available publicly
This is the MakerIOT2020 ESP12E-DEV Prototype Shield. It is similar in purpose to the above-mentioned ESP32-S Dev Prototype shield, but I have also added some additional cosmetic changes to make it a little easier to use as well.
With many of my prototype designs, I tend to sometimes leave out something, as I usually use it for my own purposes only, but with this design, as many people specifically asked for it, I took a bit more care, as it is no longer just a prototype, right?
What has changed?
The most obvious is the increased prototyping area. The initial ESP32-S version had a 60-hole breadboard-style prototyping area. The new design has 128 prototype holes.
There is also a dedicated power input header, something that I somehow left out on the ESP32-S version… The Flash and Reset push-buttons were also moved inline, and to the bottom of the shield, making it more comfortable to use.
The design retains the plated through-hole design on the prototype area with connecting tracks on both sides of the PCB to allow for a bit more current.
The big ground plane on both sides of the PCB has also been retained.
PCB Design and Schematic
Top Layer LayoutBottom Layer Layout
The prototype shield is for all purposes a breadboard. I did thus not bother with a formal schematic. I believe that it is easy enough to understand the connections by just looking at the two images above.
Manufacturing
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.
The I2C IO Card for ESP-12E I2C Base Card is another expander card for the ESP-12E I2C Base Card Project. This PCB is an address-selectable I2C module with two relays and six (6) GPIO pins, all driven from a single PCF8574 running at 3v. The relays are optically isolated, and generous mains isolation cutouts were provided to reduce the possibility of mains voltage tracking. A jumper to enable/disable the i2c pullup-resistors is also provided on the PCB.
The relays are powered from a single LDO regulator, accepting 12v DC from the 2x20pin female header on the bottom of the card. 3.3v and ground should also be applied to the card at the 2x20pin header.
It is worth mentioning that this circuit does not contain level converting circuitry and that the i2c bus thus runs at 3.3v to be compatible with ESP chips.
It is possible to use the card with other processors if the appropriate level converters are used on the i2c bus.
The Schematic
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.
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.
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
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.
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.
(Design for Manufacturability) Gerber Software Analyser
Free to Use for all PCBpartner.com Users
PCBPartner.com recently decided to release their own DFM software, which I believe they developed in-house and use themselves every day, to their customers, in order to enable their customers to design better PCBs and increase the overall quality and service satisfaction.
In this article, I will give the software a quick look and feel, and show you some of its features, while at the same time admitting upfront, that it is quite complex, and that I am also not quite well acquainted with it myself, having only a few days to play with it up to now.
What is DFM?
DFM (Design for manufacturability) analysis of incoming Gerber files is a standard and important process in any PCB factory. iPCB-DFM’s purpose is to perform this process automatically to find potential production issues with your PCB design, saving time and effort for you the PCB designer, and the PCB manufacturing engineers who are going to produce your PCB. Based on 25 years of PCB manufacturing experience, we have a massive collection of PCB DFM rules built into this software, allowing it to analyze up to 24 kinds of specifications.
It also has powerful features such as quick panalization, PCB simulation and direct Gerber editing, and can even help you count how many SMD pads are in your design!
Why do you need iPCB-DFM?
If you’re an electronic engineer, you don’t want to send your PCB Gerber files for manufacturing without checking that your design and file formats match your factory’s production capability; If you are a purchasing manager without much knowledge of PCB manufacturing processes, this tool can help you better understand the specifics of the PCBs you are ordering, making it much easier to communicate with your PCB suppliers.
-PCB simulation: generate a simulated preview of your PCB, updated in real-time by different colour settings and surface finishes, and supporting high-resolution PNG output format.
DFM Functions
1 Layer 2 Dimension 3 Minimum trace space 4 Minimum trace width 5 Hole diameter 6 Drill slot 7 Through-hole annular ring 8 Hole distance 9 Hole to trace 10 Copper to edge 11 Special holes 12 SMD size 13 Via in pads 14 Test Point 15 Component solder pads number 16 Via density 17 Surface finish area (%) 18 Routing length of travel 19 Grid wiring 20 Solder mask 21 Fiducial Point 22 SMD pad size 23 SMD pad space 24 BGAs
Gerber Edit
1 Add elements 2 Delete elements 3 Move elements 4 Copy elements 5 Adjust circuit angle 6 Rotate elements 7 Edit trace 8 Mirror 9 Positive and negative switch 10 Break trace 11 Shape edit 12 Single, rectangular marquee, polygon selection
Panelization Quick panelization – set a panelization style, tooling bar width and board space, one click to generate a panalized board in seconds in Gerber format. Advanced panelization – allows you to adjust tooling hole, v-cut, fiducial mark, solder mask for fiducial mark, drill holes on tooling bar, etc.
What does it need to run?
For the foreseeable time forward, the software only runs on Microsoft Windows. It apparently supports from Windows XP right up to Windows 11, but I only had success on Windows 10, ( I don’t have Win 11).
This was also done in a VM running in Oracle Virtualbox on an Ubuntu 22.04 LTS host. (My main operating system) Specifications for the VM were 4Gb RAM and a 50Gb Hard Disk. I have also tested it with 8Gb, but it did not make any real difference to the performance. (This is most definitely NOT related to the DFM software, but more likely to be attributed to a certain heavy resource-consuming operating system (Win 10 – which as most of us know by now, is super slow whatever you give it to run on)
Installation
Installation is straightforward and quite easy, as we can expect from any Windows software these days
Getting Started
The software starts up pretty quickly, but the gets a bit of a slowdown with a login prompt tying back to PCBPartner, where you have to enter your login credentials. This can take a bit of time to actually appear.
I am hopeful that this process will in time be streamlined as I believe that the number of users on the system will grow quite fast…
Let us look at some pictures of the UI and Menu Systems
The software also comes with a very detailed Helpfile in .pdf format
This is an extremely complex piece of software. It is also extremely powerful, and can thus be very very useful to all of us. The learning curve is extremely steep, but I do believe that it will be possible to learn and use it effectively.
As a Linux user, I would also like to see a Linux version, or at least an in-browser version, similar to a well-known EDA software package. The days that software should be confined to one operating system should be behind us ( at least in my personal view, I find it very frustrating that most other commercial CAD, CAM and EDA packages are actively forcing us to stay with one of the slowest operating systems available )
I also want to thank PCBPartner for giving me the opportunity to review and take this for a test drive. I would only have wanted to be more adept at actually getting value out of a great piece of software, but I believe that I will definitely get better at it over time.
Today we will look at the remote control unit for the Robotic Toy Car – Part 6. The project is close to being completed, and as such, there are quite a lot of final things that need to be taken care of.
One of these will definitely be the final coding, which I will release in the final part of the project, so with that in mind, let us take a look at the remote control unit.
Remote Control Unit, designed to be used with ESP-Now
I have decided to do something completely different from standard remote control units, being that I will use ESP-Now, a protocol developed by Espressif. ESP-Now runs on the Wifi hardware of the ESP8266 or ESP32 and is basically a peer-to-peer protocol, that does not require Wifi but can co-exist with it on the same device. Outdoors, ESP-Now has a range of about 100m, which should work very well for my intended use.
The Remote control, as designed, will have 4 dedicated buttons: forward, reverse, left and right, divided into two groups to make two-handed control easier, similar to a standard game controller. No input on either of the two groups will result in stopping the vehicle, in the case of forwards and backwards, and centring the steering, in the case of the left-right axis.
a 3D Rendered Image of the PCB, motion axis on SW1 and SW2, steering axis on SW3 and SW4
As I always try to make my designs somewhat reusable for other purposes, I have also broken out most of the unused GPIO pins to header pins, with also adding a jumper on GPIO16 to make deep-sleep wakeup mode possible., You can also re-use the switch pins for other purposes, just remember to first remove the 10k pull-up resistors at R14, R15, R16, and R17…
GPIO16 can be reused as well, just remove the jumper, but remember that it is pulled up through a LED and a 470ohm resistor…
There is no USB-to-serial converter onboard, I have been having quite a lot of headaches with them over the last few months, with almost all CH340G chips that I have purchased, being fake, or dead-on arrivals that don’t work… Sending them back to the suppliers, unfortunately, results in unpleasantries, because even placing them in verified working circuits, still proves them to be not working… This is however not an issue, as it is quite easy to upload the board with an external adapter.
The Schematic
Schematic Diagram
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.
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.
In this almost post we look at the power distribution PCB for the almost completed Robotic Toy Car. I had many interesting issues to solve here, especially since I did not design my own Lipo battery charger circuit, but used a very useful little commercially available unit instead, the MH-CD42
Based on a relatively difficult chip to get information on, the module is basically an integrated Lipo charge/discharge module, with a built-in boost converter that provides 5v at a maximum of 2A current. What makes it special is the ability to simultaneously provide current and voltage, as well as charge the attached LiPo cell at the same time, when connected to an external charger.
It does, however, in my view at least, also have a few serious flaws, the most irritating of these being that it will completely discharge the attached LiPo cell even when completely switched off…
I have thus tried to stop this issue from occurring by adding a switch in line with the Lipo Cell, a quite obvious solution, but it should not have been needed if the chip functioned as intended… ( As far as I can gather, the module was originally designed to be used in USB power banks. This makes the flaw even more serious, as a self-discharging power bank really defeats the purpose)
Enough of that though, when it does work, it works great. just remember that you can not apply more than 5.5v DC to the charging input of the module.
The completed Power Distribution and charging module
The Schematic
There is actually not a lot going on here, as everything is already on the supplied module. I have just added a charging port, additional power headers for 5v output and ground, as well as direct access to the LiPo Cell output, and a switch header to cut off power to the MH-CD42 when it is not in use.
The PCB
The PCB was manufactured as a 2-layer FR-4 board. The entire top layer is used as a ground plane, and the bottom layer was used for the 5v and Vbat traces, which were made as big as possible to allow for the high current ( up to 2A ) that the unit can supply to a load.
The TOP later of the PCB is a complete ground plane.The BOTTOM Layer caries only power traces for 5v and VBata 3D Render of the PCB, showing header pins and other connections
It is also worth mentioning that the VBAT pins are NOT 3.3v ( Remember that the LiPo cell can run from 4.2v down to 3.0v depending on the charge. These headers were only placed on the board to provide direct access to the LiPo cell, for use with for example an ADC input or for connection to a dev board that is already fitted with a buck converter or a suitable LDO voltage regulator.
The Actual PCB, as received from PCBWayTop Layer of the PCBBottom Layer of PCB
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.
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.
As part of my experiments with LoRa and the easy to use ATMega328P, I have recently designed quite a few LoRa based projects. In this final 2 part series, I will look at two additional projects, part of a Remote Alarm Transceiver, where I experimented with a changing a few things:
– Using LM317G adjustable voltage regulators. – Replacing my standard N-MOS based logic level converters with a dedicated chip.
LoRa Remote Alarm Transmitter – with Onboard Relay putout and two sensor inputs
How does this differ from my other LoRa Based projects?
The PCB presented above does in fact not really differ a lot from any of my existing LoRa based projects. However, there are a few subtle changes, mainly experimental changes, brought on by factors such as component availability and an attempt to reduce component counts and board size.
The first of these changes is using the LM317G voltage regulator, in the place of my usual LM1117 3.3 and 5.0 LDO regulators.
The LM317 is an old device, It has been on the market for a long time. It can supply up to 1.5A of current, and a single device can be configured to supply a wide range of different voltages by just changing two resistors. This seemed quite attractive to me, as it is getting quite difficult to reliably get quite a few components on time, and with decent pricing in the post-Covid-19 world.
The second major change would be moving away from my existing N-Mos based Logic converter setup, where I used the BSS138 and 10K resistors as logic converters. This setup works perfectly, but it has the drawback of requiring quite a lot of components. for example:
To provide logic conversion to an RA-02 module, with access to all the IO Lines (GPIO0-5 included) required 12 BSS138 Mosfets and 24 10k resistors. This is quite a lot of components. A dedicated logic converter chip would thus be a much more attractive solution.
Driver circuitry for sensor Inputs, consisting of a simple transistor input, and an optically isolated Relay output completes the circuit.
Using the LM317
The output voltage of the LM317 is typically set using two resistors, with a suitable current rating, using the following Formula
VOUT = 1.25 * ( 1 + R2/R1 )
It is also common to use a variable resistor at R2, to have fine control over the output voltage. This is due to the fact that stock resistor values do not always give you the exact voltage you require. You should also take into account that using a 5% resistor will be less accurate than a 1% resistor.
The grid below is a list of common stock resistor values for R1/R2, with the resulting voltage produced.
R1 vs R2 Grid for use in selecting fixed output voltage
R2\R1
150
180
220
240
270
330
370
390
470
68
1.82
1.72
1.64
1.60
1.56
1.51
1.48
1.47
1.43
82
1.93
1.82
1.72
1.68
1.63
1.56
1.53
1.51
1.47
100
2.08
1.94
1.82
1.77
1.71
1.63
1.59
1.57
1.52
120
2.25
2.08
1.93
1.88
1.81
1.70
1.66
1.63
1.57
150
2.50
2.29
2.10
2.03
1.94
1.82
1.76
1.73
1.65
180
2.75
2.50
2.27
2.19
2.08
1.93
1.86
1.83
1.73
220
3.08
2.78
2.50
2.40
2.27
2.08
1.99
1.96
1.84
240
3.25
2.92
2.61
2.50
2.36
2.16
2.06
2.02
1.89
270
3.50
3.13
2.78
2.66
2.50
2.27
2.16
2.12
1.97
330
4.00
3.54
3.13
2.97
2.78
2.50
2.36
2.31
2.13
370
4.33
3.82
3.35
3.18
2.96
2.65
2.50
2.44
2.23
390
4.50
3.96
3.47
3.28
3.06
2.73
2.57
2.50
2.29
470
5.17
4.51
3.92
3.70
3.43
3.03
2.84
2.76
2.50
560
5.92
5.14
4.43
4.17
3.84
3.37
3.14
3.04
2.74
680
6.92
5.97
5.11
4.79
4.40
3.83
3.55
3.43
3.06
820
8.08
6.94
5.91
5.52
5.05
4.36
4.02
3.88
3.43
1000
9.58
8.19
6.93
6.46
5.88
5.04
4.63
4.46
3.91
1200
11.25
9.58
8.07
7.50
6.81
5.80
5.30
5.10
4.44
1500
13.75
11.67
9.77
9.06
8.19
6.93
6.32
6.06
5.24
1800
16.25
13.75
11.48
10.63
9.58
8.07
7.33
7.02
6.04
2200
19.58
16.53
13.75
12.71
11.44
9.58
8.68
8.30
7.10
2700
23.75
20.00
16.59
15.31
13.75
11.48
10.37
9.90
8.43
3300
28.75
24.17
20.00
18.44
16.53
13.75
12.40
11.83
10.03
As you can see from the table above, using stock resistors, the output voltage is reasonably accurate, but it is quite obvious that you will need a potentiometer to get exact values. Another issue will definitely be heat dissipation. In my PCB design, I have used the SOT-223 package of the component, with a PCB heatsink, built directly into the layers. With the LM1117 LDO regulators, these work extremely well.
Logic Level Conversion
In this design, I used my standard Logic Level conversion circuit, comprised of a BSS138 N-Mos with two 10 k resistors. This circuit, although a bit cumbersome with lots of components if you need many logic converters, is very stable, and functions extremely well.
Conclusion
This circuit was designed as a two-part prototype, with the goal of experimenting with different voltage regulators, and in part 2, with a single chip 8 channel logic converter. As such, I do not feel comfortable releasing the full schematics to you at this stage, do so anyway in the interest of learning. The circuit works, but there are many issues with the regulators:
– Overheating at input voltages above 8.0v The PCB heatsink will have to be improved, or even a different package for the LM317 with the possibility to attach an external heatsink.
– The voltages do not seem stable, especially on the 3.3-volt side.
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.
Every once in a while, we get an opportunity to take advantage of an exceptional deal. Recently, the friendly people at PCBPartner.com reached out to me with another great deal… “Get your next PCB for only $1!”
You will get the following: 10 FR-4 PCB, 1 or 2 layers, with Green Soldermask, in dimensions not exceeding 100mmx100mm, Manufactured and delivered to your door for only 1 (one) $USD. This promotion will be valid until 31 May 2022, with AIRMAIL shipping included.
PCBPartner.com is owned and operated by Kinji Group, established in 1997. We have over 20 years of experience in PCB manufacturing, PCB design, component manufacturing and distribution, PCB assembly and PCB CAD software development.
While Kinji Group has 3 PCB factories in China, we have also developed strategic partnerships with more than 15 other factories around Asia. We, therefore, have a large group of specialists in PCB manufacturing, quality control, technical support and part sourcing to support your innovative ideas and products.
Our over 500 employees are spread across 8 branches in Mainland China (Shenzhen, Dongguan, Shanghai, Wuxi, Chengdu, Xiamen), Hong Kong SAR, and Taiwan. And we’re still growing!
Why Should you use PCBPartner for your next PCB order?
Variety of PCB Material
Up to 54 layers during PCB manufacturing.
FR-4 with different tg (135,150,170), CTI 600 (Halogen free) PCB material, Aluminium base PCB, Flexible PCB, Rigid-Flexible PCB, Rogers, and many more materials. Whatever material you need, they can deliver.
Special PCB Specifications:
Regular PCB production for these special PCB specifications
● Impedance control
● Custom-layer stack up
● 1-3 oz copper thickness for outer/inner layers
● Hard gold, ENEPIG, OSP surface finish
● Two different solder mask colours on one PCB
● Edge connector plating
● Edge plating
● Via filled with aluminium/resin
● And more…
Fast Lead Time
Turnaround is quick as prototypes usually take as little as 24 hours to produce, with a direct pickup service from their warehouse. They partner with DHL and FedEx for this to make sure you get your PCB in the shortest time possible. They also offer express production options for small and medium-sized batches so that you get your boards EVEN quicker.
Competitive Pricing
Get competitive pricing on prototypes and your future mass production. For any mass production orders, contact them so that they can find the best pricing and shipping solutions to maintain your competitiveness
Ordering boards in bulk? Save more the larger your order:
US$10 off orders of 100+
US$10 off orders of 100+
US$50 off orders of 500+
US$120 off orders of 1000+
Quality Control
After 20 years, they have built a strict standard of quality – their quality control teams ensure all PCBs pass the AOI and E-test with 100%.
Technical Support
They have an experienced PCB manufacturing and engineering team to help you detect potential mistakes in your Gerber files. They also use – and have used for 15+ years – a reliable PCB testing software solution, iPCB, to detect mistakes in designs.
Excellent Customer Service Team
They have a passionate (and patient!) customer service team to help you solve any problems while ordering, handle engineering questions, or answer any after-sales service request. They will respond to you within 1 working day, that’s their customer service guarantee.
Flexible Payment Term
If you have a large amount of PCB to order every month and want to work with them for AMS 30 payment, they will be happy to sign an agreement with you.
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.
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).
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.
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!
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…
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…
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.
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.
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… 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.
