danjperron / rp2040-modbus_example

Demo repo with Modbus RTU implementation for rp2040 (Raspberry Pi Pico) with C++ SDK

Modbus RTU Slave library for Raspberry Pi Pico (RP2040) based on the C++ SDK

This repository contain working example Modbus RTU Slave implementation for rp2040 (Raspberry Pi Pico) with C++ SDK

This is a fork from https://github.com/gleboss-redfab/rp2040-modbus_example
From the fork base class modbusManager, modbus.hpp, I create a subclass ModbusPico.
This way I just need to modify ModbusPico class to add function.

On the current example the modbus layout has 8 outputs, 8 inputs, one wire DS18B20 line and analog ADC inputs.

Update 6Feb 2024

• add two BME280/BMP280 sensors on i2c gpio10 and gpio11
  input register address
  2200 SENSOR1 type, 0 = none/error, 0x58= BMP280, 0x60=BME280
  2201 SENSOR2 type, 0 = none/error, 0x58= BMP280, 0x60=BME280
  22.. future usage
  2210..19 SENSOR1 RANGE
  2220..29 SENSOR2 RANGE
  2230... future usage
  

  For BME280 offset 0..1 signed 32bits temper temperature * 100 in celsius
  offset 2..3 unsigned 32bits Humidity * 1024 in %
  offset 4..5 unsigned 32bits Pressure * 100 in HPa
  offset 6..9 invalid
  

  For BMP280 offfset 2..3 for humidity will be set to zero.
  N.B. if no sensor the data will be zero
  
  Check readBME280.py for info
  

Features:

• Modbus RTU Slave
• RS-485 support
• C++ style class
• Registers layout
• Separate setup read-only and read-write registers
• UART 0 and 1 support
• it works out of box and tested

How to use the example:

• Tune VS Code for Raspberry Pico development (instruction)
• You can use 2nd Raspberry Pico as a bootloader and debuger (instruction)
• Modify launch.json and setting.json files in .vscode according to your environment
• Start the debugging session
• Use Modbus Master emulator for connection (ModBus Poll for example)
• Change UART parameters in main.cpp and registers layout in modbus.cpp for your purpose
• Change stored data inside Modbus Manager class
• Change Switch-case optins according to your data and registers in mb_read_holding_register() and mb_write_single_register()

How to compile using a raspberry Pi connected to the swd

• Follow the installation step from the PDF "Raspberry Pi Pico c/C++ SDK". https://www.raspberrypi.com/documentation/microcontrollers/c_sdk.html
• clone the github. git clone https://github.com/danjperron/rp2040-modbus_example.git
  
• Enter the rp2040-modbus_example folder. cd rp2040-modbus_example
  
• Create the build folder. mkdir build
  
• Enter the build folder. cd build
  
• Create the cmake environnement. cmake ..
• Compile. make
  
• To transfer use openocd. https://iosoft.blog/2019/01/28/raspberry-pi-openocd