Easy to Use RA-02 Breakout Module

Original RA-02 breakout Module, next to improved RA-02 breakout Module

Most Makers and electronics enthusiasts may already know of the RA-02 LoRa Module. Many of them might own an RA-02 Breakout module or two… For those who do, they will surely know about the problems encountered with using this particular breakout module…

The RA-02 module, in itself, is a great piece of kit, and when used on a custom PCB, which was designed with all the little secrets of this module taken into consideration, is a pleasure. Using the RA-02 breakout module, in its existing form factor, does however present quite a few unique challenges, which, if you are unaware of them, can cause quite a few frustrating moments, or even result in permanent damage to the module…

In this post, we will focus on :
1) The Challenges of the existing commercially available RA-02 Breakout Module
2) My Solution to above mentioned Challenges
3)Testing the Module
Maker Uno – An Arduino Uno Clone
Maker Nano RP2040
Maker Pi Pico – Raspberry Pi Pico breakout module


What are these challenges:

1) The module is based on the SX1278 chip from Semtech and is a 3v device. The IO pins are NOT 5v compatible but seem to work for a few hours or so when used with 5v… This causes many people, especially on Youtube, to assume that it is ok to send 5v logic signals to this module…

I have still not seen any Youtube video telling viewers to at least use a resister divider or logic converter… People just don’t know, and those that know seem to be keeping quiet!

Adding logic converters is in fact specified by the datasheet.

2) Adding logic converters means adding additional wiring, and for a breadboard based project, that adds to the complexity.

3) You have a total of 4 ground pins that need to be connected. not connecting all of them, causes funny things to happen, from overheating down to failure… ( My personal experience while researching this project)

4) The existing breakout module is not breadboarding compatible, resulting in a floating assembly with wires going everywhere, which results in unstable connections etc…

Basically something similar to the picture below:

RA-02 breakout Module (original) with Maker Uno and Level converter module

In this picture, I have an existing RA-02 Breakout Module, with an 8 channel Logic converter and an Arduino Uno clone, along with all the needed wiring to make this setup possible… Quite a lot of wires indeed…

My solution:

I design and use quite a few LoRa PCBs and on all of them, I implement logic conversion using the BSS138 N-MOS Mosfet and 10k resistors. It is a cheap and reliable solution, but it can take up quite a lot of space on a PCB, as this means 11 Mosfets and 22 10k resistors if I were to provide level conversion to all of the RA-02’s GPIO and IO pins…

I also have the constant problem of many unnecessary wires, many of which sometimes fail straight out of the box, when prototyping something. I partly solved that by designing a few dedicated PCB solutions, but that is not always ideal,

Using a dedicated Logic Converter IC, and Mosfet based converters to make up the difference, on a breadboard compatible module, seemed like a good idea, so I went ahead and designed the following solution:

RA-02 breakout Module on a breadboard

The breakout board module is breadboard compatible, and also has clearly marked pins to indicate the 3v and 5v sides of the module.

Testing the Module:

Using a 5v device ( Cytron’s Maker Uno )

For my first test, I decided to test with an Arduino Uno Clone, since that is what most Makers and students will have access to. I used Cytron’s Maker Uno platform, which is equipped with some added goodies, in the form of diagnostic LED etc to make prototyping a lot easier.

RA-02 breakout Module, connected to Maker Uno

As we can clearly see, It is only necessary to connect to the 5v logic side of the module, as well as provide 3v and 5v + GND to the module

In this test, I used Sandeep Mistry’s LoRa Library, with the Arduino IDE to do a quick test sketch.

Connections are as follows:

RA-02 Module Maker Uno

MISO D12

MOSI D11

SCK D13

NSS D10

RST D9

DIO0 D2

OE D8

Full code download

Let us look at some important sections though, to thoroughly understand how to use the module:

Pin Declaration

#include <SPI.h>       // include libraries

#include <LoRa.h> // I used Sandeep Mistry’s LoRa Library, as it is easy to use and understand

const int csPin = 10;     // LoRa radio chip select

const int resetPin = 9;    // LoRa radio reset

const int irqPin = 2;     // change for your board; must be a hardware interrupt pin

const int OEPin = 8;     // Output Enable Pin, to enable the Logic Converter

In the Setup function, we need to do a bit of extra work, since our Maker Uno ( or your Arduino Uno ) is a 5v device…

void setup() {

 Serial.begin(115200); // initialize serial

 pinMode(OEPin,OUTPUT); // Setup the OE pin as an Outout

 digitalWrite(OEPin,HIGH); // and Pull it High to enable the logic converter

 while (!Serial);

 Serial.println(“LoRa Duplex – Set spreading factor”);

 // override the default CS, reset, and IRQ pins (optional)

 LoRa.setPins(csPin, resetPin, irqPin); // set CS, reset, IRQ pin

 if (!LoRa.begin(433E6)) {       // initialize ratio at 433 MHz

  Serial.println(“LoRa init failed. Check your connections.”);

  while (true);            // if failed, do nothing

 }

 LoRa.setSpreadingFactor(8);      // ranges from 6-12,default 7 see API docs

 Serial.println(“LoRa init succeeded.”);

}

A comparison, using the standard RS-02 Breakout module, together with one of my own “Arduino type PCB”

ATMEGA328P with 8 Channel Logic Converter.

Original RA-02 Breakout Module, connected to an ATMEGA328P PCB with onboard Level converters

As we can see, you need quite a lot more wires to make this work. It is also worth noting that we have only 8 level converters on this ATMEGA328P PCB, in order to use all of the RA-02’s GPIO, we will need to add an additional external logic converter as well.

Using a 3v Device:

Cytron’s Maker Nano RP2040

For my second test, I decided to be a bit brave, and try to use the new Raspberry Pi Pico ( RP2040 Microprocessor ). I have quite a few of them lying around and have never really done a lot with them, due to the fact that I do not really like using MicroPython or CircuitPython, and also because the recently released Arduino Core for the RP2040 still being quite new… I decided to use a development board that I recently bought from Cytron, the Maker Nano RP2040, as it has all the added diagnostic features to make my life a bit easier, I will also include a test with an original Pi Pico board, to make it more accessible to everyone out there.

RA-02 Breakout Module, connected to Maker Nano RP2040

Once again, I used Sandeep Mistry’s LoRa Library, with the exact same Arduino sketch, used for the Maker Uno test. (I obviously needed to change the pin numbers though, as the RP2040 uses different pins for its SPI interface).

Maker Nano RP2040 RA-02 Breakout Module

NSS 17

MOSI 19

MISO 16

SCK 18

RST 9

DIO0 8

In this case, we DO NOT need the OE pin, as the RP2040 is a native 3v device. The level converter can thus stay disabled, with its pins in tri-state ( high impedance ) mode.

If we look at the code, it is similar to the Maker Uno’s code, with only the Pin declarations needing a change

#include <SPI.h>       // include libraries

#include <LoRa.h>

const int csPin = 17;     // LoRa radio chip select

const int resetPin = 9;    // LoRa radio reset

const int irqPin = 8;     // change for your board; must be a hardware interrupt pin

byte msgCount = 0;      // count of outgoing messages

int interval = 2000;     // interval between sends

long lastSendTime = 0;    // time of last packet send

// Note that SPI has different names on the RP2040, and it has 2 SPI ports. We used port 0

// CIPO (Miso) is on pin 16

// COPI (Mosi) is on pin 19

// SCK is on pin 18

// CE/SS is on pin 17, as already declared above

I did not use a breadboard, in order to make things as easy as possible.

Cytron’s Maker Pi Pico – A Pi Pico on a breakout PCB

RA-02 Breakout Module, connected to Maker Pi Pico

To make things a bit easier, without having to resort to using a breadboard, I decided to do the Original Pi Pico test using the Maker Pi Pico PCB. This PCB is basically a big breakout module, with detailed pin numbers and some diagnostic LEDs, but it also uses a native Pi Pico, soldered directly to the PCB, by means of the castellated holes… So, While technically not being a true standalone Pico, It makes my life easier and was thus used for the test, as I can be sure that the pins are labelled exactly the same as on the original Pico.

The code used for the Maker Nano RP2040 works perfectly, with no changes required.

This post is getting quite long by now, so I have decided not to include my tests of the ESP-12E ( NodeMCU ) or ESP32 development boards here as well… They also function as expected.

In Summary

When I started this project, I set out to solve a problem ( personal to me ), that could potentially help a lot of other people use the RA-02 Module for more projects and tasks. The Breakout module in its current form can also be used with the RA-01h module (915Mhz Module) without any changes. All GPIO pins are broken out, and accessible through full logic converted pins on both sides of the breakout module.

I hope that this will be useful to someone. I am also not releasing the full schematics at this stage, as I may decide to make some minor cosmetic changes in the near future.

The PCB can however be ordered from PCBWay in its current form and works 100% as expected. The BOM file is available with the ordered PCB as usual.

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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,

PCBWay Start Quotation Page

4) Click on PCB Instant Quote

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

Quick order PCB from PCBWay

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.

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PCBWay PCB Parameters - Page 2

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 ).

PCBWay Stencil
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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.

Simplifying Robotics with Raspberry Pi® RP2040

Introducing the Cytron Maker RP2040

Cytron Maker Pi RP2040 features the first microcontroller designed by Raspberry Pi – RP2040, embedded on a robot controller board. This board comes with a dual-channel DC motor driver, 4 servo motor ports and 7 Grove I/O connectors, ready for your next DIY robot/motion control project. Now you can build a robot while trying out the new RP2040 chip.

 

The DC motor driver on board is able to control 2x brushed DC motors or 1x bipolar/unipolar stepper motor rated from 3.6V to 6V, providing up to 1A current per channel continuously. The built-in Quick Test buttons and motor output LEDs allow a functional test of the motor driver in a quick and convenient way, without the need of writing any code. Vmotor for both DC and servo motors depends on the input voltage supplied to the board.


Credit: 3D robot parts designed by Camilo Parra Palacio from OttoDIY Community.
 


Credit: Self-watering Planter 3D parts on Thingiverse.
 

Maker Pi RP2040 features all the goodness of Cytron’s Maker series products. It too has lots of LEDs useful for troubleshooting (& visual effects), is able to make quite some noise with the onboard piezo buzzer and comes with push buttons ready to detect your touch.

There are three ways to supply power to the Maker Pi RP2040 – via USB (5V) socket, with a single cell LiPo/Li-Ion battery or through the VIN (3.6-6V) terminals. However, only one power source is needed to power up both controller board and motors at a time. Power supply from all these power sources can all be controlled with the power on/off switch onboard.

Cytron Maker Pi RP2040 is basically the Raspberry Pi Pico + Maker series’ goodness + Robot controller & other useful features. Therefore this board is compatible with the existing Pico ecosystem. Software, firmware, libraries and resources that are developed for Pico should work seamlessly with Cytron Maker Pi RP2040 too.

CircuitPython is preloaded on the Maker Pi RP2040 and it runs a simple demo program right out of the box. Connect it to your computer via USB micro cable and turn it on, you will be greeted by a melody tune and LEDs running light. Press GP20 and GP21 push buttons to toggle the LEDs on/off while controlling any DC and servo motors connected to it to move and stop. With this demo code, you get to test the board the moment you receive it!

While connected to your computer, a new CIRCUITPY drive appears. Explore and edit the demo code (code.py & lib folder) with any code editor you like, save any changes to the drive and you shall see it in action in no time. That’s why we embrace CircuitPython – it’s very easy to get started. Wish to use other programming languages? Sure, you are free to use MicroPython and C/C++ for Pico/RP2040. For those of you who love the Arduino ecosystem, please take a look at this official news by Arduino and also the unofficial Pico Arduino Core by Earle F. Philhower.

Features:

  • Powered by Rapberry Pi RP2040
    • Dual-core Arm Cortex-M0+ processor
    • 264KB internal RAM
    • 2MB of Flash memory
    • the exact same specifications with Raspberry Pi Pico
  • Robot controller board
    • 4x Servo motors
    • 2x DC motors with quick test buttons
  • Versatile power circuit
    • Automatic power selection: USB 5V, LiPo (1-cell) or Vin (3.6-6V)
    • Built-in 1-cell LiPo/Li-Ion charger (over-charged & over-discharged protection)
    • Power on/off switch
  • 13x Status indicator LEDs for GPIO pins
  • 1x Piezo buzzer with mute switch
  • 2x Push button
  • 2x RGB LED (Neopixel)
  • 7x Grove ports (flexible I/O options: digital, analog, I2C, SPI, UART…)
  • Preloaded with CircuitPython by default
  • Mouting holes
    • 4x 4.8mm mounting hole (LEGO® pin compatible)
    • 6x M3 screw hole

Maker Pi RP2040 VS. Maker Pi Pico?


Board Layout:

Dimension:

88mm(L) x 64mm(W) x 13mm(H)

Packing List:

Resources:

Maker Pi Pico – Programming your board

It has been almost a week now since I received my Maker Pi Pico from Cytron Technologies in Malysia. Most of this time has been spent getting to know the RP2040 Microchip, and how to effectively program it. Cytron has done an excellent job being very quick to market with a development board based on the RPi Pico, as well as providing a very good starting foundation to new Pico users ( which I believe is all of us, at least at this stage 🙂 )



It is super easy to put your Maker Pi Pico into Upload Mode. No need to plug and unplug your USB Cable.
– Push and hold the RUN Button ( Located on the Bottom Right, Above the GP20 Push Button) .
– While holding RUN pressed, press the BOOTSEL button on the Pico, and keep it pressed.
– Release RUN and then release BOOTSEL.

You are now in BOOTSEL Mode. You can donload the official Micropython .uf2 file from the link below, or from the Raspberry Pi Website. It is also possible to install Micropython directly from inside the Thonny Python IDE.

You can also find a few examples of code written for the RPi Pico on Cytron’s Github Page

The SDK above contains all the information needed to setup the Thonny IDE to use with your Pico ( Chapter 4 ).

In my next post, I will post some of my own example code for using some additional peripherals.

Thank you

Introducing the Raspberry Pi Pico

It is not often that we get the opportunity to be one of the first people to get our hands onto a new product, So when my friends at Cytron Technologies asked me if I would like to do a review on a new Raspberry Pi product last week, I was definitely interested. Details were few, as the product was still under an NDA, but at last, I got the datasheets and some details on Tuesday, enough to start writing about the new product before the big Launch on Thursday the 21st of January 2021…

So, what am I trying to say? Well, It seems that the Raspberry Pi Foundation has released a new product, and from first impressions, it seems to be a game-changer… Lets not get confused. I am not speaking about a full size Raspberry Pi Board, or the compute module… No, The Pi Foundation has released an RP2040 Microprocessor based development board, in the same form factor as an Arduino Nano.

Raspberry Pi Pico Microcontroller Board

This will be an introduction post, and when I receive the device to play with, which will be soon, I will start with a short series on its features and capabilities… For now, lets look at some of the specifications

Front and Back view of the Raspberry Pi Pico

Features:

Raspberry Pi Pico has been designed to be a low cost yet flexible development platform for RP2040, with the following
key features:
• RP2040 microcontroller with 2MByte Flash
• Micro-USB B port for power and data (and for reprogramming the Flash)
• 40 pin 21×51 ‘DIP’ style 1mm thick PCB with 0.1″ through-hole pins also with edge castellations
◦ Exposes 26 multi-function 3.3V General Purpose I/O (GPIO)
◦ 23 GPIO are digital-only and 3 are ADC capable
◦ Can be surface mounted as a module
• 3-pin ARM Serial Wire Debug (SWD) port
• Simple yet highly flexible power supply architecture
◦ Various options for easily powering the unit from micro-USB, external supplies or batteries
• High quality, low cost, high availability
• Comprehensive SDK, software examples and documentation
RP2040 key features: (Datasheet available for download at the bottom of this post)
• Dual-core cortex M0+ at up to 133MHz
◦ On-chip PLL allows variable core frequency
• 264K multi-bank high performance SRAM
• External Quad-SPI Flash with eXecute In Place (XIP)
• High performance full-crosspoint bus architecture
• On-board USB1.1 (device or host)
• 30 multi-function General Purpose IO (4 can be used for ADC)
◦ 1.8-3.3V IO Voltage (NOTE Pico IO voltage is fixed at 3.3V)
• 12-bit 500ksps Analogue to Digital Converter (ADC)
• Various digital peripherals
◦ 2x UART, 2x I2C, 2x SPI, up to 16 PWM channels
◦ 1x Timer with 4 alarms, 1x Real Time Counter
• Dual Programmable IO (PIO) peripherals
◦ Flexible, user-programmable high-speed IO
◦ Can emulate interfaces such as SD Card and VGA

Pico provides minimal (yet flexible) external circuitry to support the RP2040 chip (Flash, crystal, power supplies and
decoupling and USB connector). The majority of the RP2040 microcontroller pins are brought to the user IO pins on the left and right edge of the board. Four RP2040 IO are used for internal functions – driving an LED, on-board Switched Mode Power Supply (SMPS) power control and sensing the system voltages.
Pico has been designed to use either soldered 0.1″ pin-headers (it is one 0.1″ pitch wider than a standard 40-pin DIP package) or can be used as a surface mountable ‘module’, as the user IO pins are also castellated. There are SMT pads underneath the USB connector and BOOTSEL button, which allow these signals to be accessed if used as a reflow-soldered SMT module.

The Pico uses an on-board buck-boost SMPS which is able to generate the required 3.3 volts (to power RP2040 and external circuitry) from a wide range of input voltages (~1.8 to 5.5V). This allows significant flexibility in powering the unit from various sources such as a single Lithium-Ion cell, or 3 AA cells in series. Battery chargers can also be very easily integrated with the Pico powerchain.
Reprogramming the Pico Flash can be done using USB (simply drag and drop a file onto the Pico which appears as a mass storage device) or via the Serial Wire Debug (SWD) port. The SWD port can also be used to interactively debug code running on the RP2040.

Mechanical Specifications

The Raspberry Pi Pico is a single sided 51x21mm 1mm thick PCB with a micro-USB port overhanging the top edge and dual castellated/through-hole pins around the remaining edges. Pico is designed to be usable as a surface mount module as well as being in Dual Inline Package (DIP) type format, with the 40 main user pins on a 2.54mm (0.1″) pitch grid with 1mm holes and hence compatible with veroboard and breadboard. Pico also has 4x 2.1mm (+/- 0.05mm) drilled mounting holes to provide for mechanical fixing, see Figure 3.

Mechanical specifications for the Raspberry Pi Pico

Conclusion

I hope that this is enough details to get all of you interested and eager for more details…
In the next part of this series, I will focus on getting started with this new board, as well as do the official unboxing…
Please stay tuned for more details…