Overview

RP2350-Relay-6CH

SPI / I2C / RS485

RP2350-Relay-6CH-W

SPI / I2C / RS485

Introduction

RP2350-Relay-6CH and RP2350-Relay-6CH-W are industrial-grade 6-channel relay series products based on the RP2350B main controller, both equipped with peripheral interfaces such as RS485 and Pico, and featuring multiple protection circuits including power isolation and optocoupler isolation. Among them, the RP2350-Relay-6CH-W additionally supports WiFi and Bluetooth wireless communication functions. This series is designed with a focus on safety and stability, providing industrial-grade reliable protection.

Features

RP2350B microcontroller chip officially designed by Raspberry Pi
Unique dual-core and dual-architecture design, equipped with dual-core ARM Cortex-M33 processor and dual-core Hazard3 RISC-V processor, flexible clock running up to 150 MHz, supporting flexible switching between the two architectures
Equipped with Raspberry Pi Radio Module 2 module, supporting Wi-Fi 4 wireless network and Bluetooth 5.2 (Wi-Fi module version only)
Built-in 520KB of SRAM and 16MB of on-chip Flash
Type-C port, easier to use
High quality relay, contact rating: ≤10A 250V AC or ≤10A 30V DC
Onboard isolated RS485 interface, for connecting to various RS485 Modbus industrial modules or sensors
Onboard Pico compatible interfaces can be adapted to some Raspberry Pi Pico HAT, for expanding more functions such as RTC / CAN / RS232 / LoRa / sensor, etc.
Onboard power supply screw terminal, supports 7~36V wide voltage input, suitable for industrial applications
Onboard optocoupler isolation to prevent interference with control chip from external high-voltage circuit connected to the relay
Onboard digital isolation to avoid external signal interference with the control chip
Onboard integrated power isolation, providing stable isolation voltage, no extra power supply required for the isolated terminal
Built-in buzzer, RGB colorful LED, power supply and RS485 TX/RX indicators for monitoring the operating status of the module
Rail-mounted ABS protective enclosure, easy to install, safe to use
USB1.1 host and slave device support
Low-power sleep and dormant modes
Drag-and-drop programming via USB mass storage
34 × multi-functional GPIO pins
2 × I2C, 2 × UART, 8 × 12-bit ADC and 24 × controllable PWM channels
Accurate clock and timer on-chip
Temperature sensor
On-chip accelerated floating-point library
12 × Programmable I/O (PIO) state machines for custom peripheral support

Pinout Definition

Dimensions

Electrical and Relay Safety Instructions

This product must be operated by professional electricians or qualified personnel. During use, ensure electrical safety, leakage protection, and proper insulation.
Before installing, maintaining, or replacing the relay device, always turn off the power and unplug the device.
Do not attempt to disassemble the relay device to avoid damage or the risk of electric shock.
Properly install and place the relay device. Do not use it in humid, overheated, flammable, or explosive environments to prevent accidents caused by improper installation or use.

1. Load Matching

Ensure the relay's rated voltage and current match the load. Do not exceed the rated capacity.
For inductive loads (motors, coils, lamps, etc.), the starting current may be much higher than the rated current. Choose a relay with sufficient current margin.

2. Short Circuit and Overcurrent Protection

Install a fuse or circuit breaker in the relay circuit to prevent damage due to short circuits or accidental overcurrent.
Ensure the load circuit has no short circuits during wiring, and select protection components with appropriate current ratings if necessary.

3. Arc and Switching Protection

Relay switching generates arcs, which can cause contact wear or welding.
For inductive loads, it is recommended to use RC snubber circuits or varistors for arc suppression.

4. Installation Environment

Do not use the relay in humid, high-temperature, flammable, explosive, or dusty environments.
Install the relay securely to avoid vibrations or shocks that may cause misoperation or damage.

5. Power-Off Operation

Always cut off power before maintenance, wiring, or replacing the relay to ensure personnel and device safety.
Latching relays are only powered when changing state. Avoid strong vibrations or strong magnetic fields while the relay is unpowered.

6. Status Confirmation

After powering on, confirm or reset the relay status as needed to prevent abnormal operation caused by transportation, installation, or external disturbances.
Avoid power interruption during relay operation to prevent uncertain status or contact damage.

7. Regular Inspection

Periodically inspect relay contacts, terminals, and insulation to ensure proper operation.
If abnormal heating, odor, or burn marks are detected, immediately cut off power and replace the relay.

Pico Getting Started

Firmware Download

MicroPython Firmware Download

C_Blink Firmware Download

Basic Introduction

Raspberry Pi Pico Basics

MicroPython Series

Install Thonny IDE

To facilitate the development of Pico/Pico2 boards with MicroPython on a computer, it is recommended to download the Thonny IDE

Download Thonny IDE and follow the steps to install, the installation packages are all Windows versions, please refer to Thonny's official website for other versions
After installation, configure the language and motherboard environment for the first use. Since we are using Pico/Pico2, pay attention to selecting the Raspberry Pi option for the motherboard environment

Configure MicroPython environment and choose Pico/Pico2 port
- Connect Pico/Pico2 to your computer first, and in the lower right corner of Thonny left-click on the configuration environment option --> select Configure interpreter
- In the pop-up window, select MicroPython (Raspberry Pi Pico), and choose the corresponding port

Flash Firmware

Click OK to return to the Thonny main interface, download the corresponding firmware library and flash it to the device, and then click the Stop button to display the current environment in the Shell window
Note: Flashing the Pico2 firmware provided by MicroPython may cause the device to be unrecognized, please use the firmware below or in the package
How to download the firmware library for Pico/Pico2 in windows: After holding down the BOOT button and connecting to the computer, release the BOOT button, a removable disk will appear on the computer, copy the firmware library into it
How to download the firmware library for RP2040/RP2350 in windows: After connecting to the computer, press the BOOT key and the RESET key at the same time, release the RESET key first and then release the BOOT key, a removable disk will appear on the computer, copy the firmware library into it (you can also use the Pico/Pico2 method)

MicroPython Series Tutorials

【MicroPython】machine.Pin class function details
【MicroPython】machine.PWM class function details
【MicroPython】machine.ADC class function details
【MicroPython】machine.UART class function details
【MicroPython】machine.I2C class function details
【MicroPython】machine.SPI class function details
【MicroPython】rp2.StateMachine class function details

C/C++ Series

For C/C++, it is recommended to use Pico VSCode for development. This is a Microsoft Visual Studio Code extension designed to make it easier for you to create, develop, and debug projects for the Raspberry Pi Pico series development boards. No matter if you are a beginner or an experienced professional, this tool can assist you in developing Pico with confidence and ease. Here's how to install and use the extension.

Official website tutorial: https://www.raspberrypi.com/news/pico-vscode-extension/
This tutorial is suitable for Raspberry Pi Pico, Pico2 and the RP2040 and RP2350 series development boards developed by Waveshare
The development environment defaults to Windows11. For other environments, please refer to the official tutorial for installation

Install VSCode

First, click to download pico-vscode package, unzip and open the package, double-click to install VSCode

Note: If vscode is installed, check if the version is v1.87.0 or later

Install Extension

Click Extensions and select Install from VSIX
Select the package with the vsix suffix and click Install
Then vscode will automatically install raspberry-pi-pico and its dependency extensions, you can click Refresh to check the installation progress
The text in the right lower corner shows that the installation is complete. Close VSCode

Configure Extension

Open directory C:\Users\username and copy the entire .pico-sdk to that directory
The copy is completed

Open vscode and configure the paths for the Raspberry Pi Pico extensions

The configuration is as follows:

Cmake Path:
${HOME}/.pico-sdk/cmake/v3.28.6/bin/cmake.exe

Git Path:
${HOME}/.pico-sdk/git/cmd/git.exe    

Ninja Path:
${HOME}/.pico-sdk/ninja/v1.12.1/ninja.exe

Python3 Path:
${HOME}/.pico-sdk/python/3.12.1/python.exe

New Project

The configuration is complete, create a new project, enter the project name, select the path, and click Create to create the project
To test the official example, you can click on the Example next to the project name to select
The project is created successfully

Compile Project

Select the SDK version
Select Yes for advanced configuration
Choose the toolchain, 13.2.Rel1 is applicable for ARM cores, RISCV.13.3 is applicable for RISCV cores. You can select either based on your requirements
Select Default for CMake version (the path configured earlier)
Select Default for Ninja version
Select the development board
Click Compile to compile
The .uf2 format file is successfully compiled

Flash Firmware

Here are two methods for flashing firmware

Flash firmware using the pico-vscode plugin
Connect the development board to the computer, click Run to flash the firmware directly

Flash the firmware manually

1. Press and hold the Boot button
2. Connect the development board to the computer     
3. Then the computer will recognize the development board as a USB device.
4. Copy the .uf2 file to the USB drive, and the device will automatically restart, indicating successful program flashing.

Import Project

Select the project directory and import the project
The Cmake file of the imported project cannot have Chinese (including comments), otherwise the import may fail
To import your own project, you need to add a line of code to the Cmake file to switch between pico and pico2 normally, otherwise even if pico2 is selected, the compiled firmware will still be suitable for pico
```
set(PICO_BOARD pico CACHE STRING "Board type")
```

Update Extension

The extension version in the offline package is 0.15.2, and you can also choose to update to the latest version after the installation is complete

Arduino IDE Series

Install Arduino IDE

First, go to Arduino official website to download the installation package of the Arduino IDE.
Here, you can select Just Download.
Once the download is complete, click Install.

Notice: During the installation process, it will prompt you to install the driver, just click Install

Arduino IDE Interface

After the first installation, when you open the Arduino IDE, it will be in English. You can switch to other languages in File --> Preferences, or continue using the English interface.
In the Language field, select the language you want to switch to, and click OK.

Install Arduino-Pico Core in Arduino IDE

Open the Arduino IDE, click on the file in the top left corner, and select Preferences
Add the following link to the attached board manager URL, and then click OK
This link already includes board versions such as RP2040 and RP2350. Please visit arduino-pico for the latest version files
```
https://github.com/earlephilhower/arduino-pico/releases/download/4.5.2/package_rp2040_index.json
```
Note: If you already have an ESP32 board URL, you can use a comma to separate the URLs as follows:
```
https://dl.espressif.com/dl/package_esp32_index.json,https://github.com/earlephilhower/arduino-pico/releases/download/4.5.2/package_rp2040_index.json
```
Click Tools > Development Board > Board Manager > Search pico, as my computer has already been installed, it shows that it is installed

Upload Demo at the First Time

Press and hold the BOOTSET button on the Pico board, connect the pico to the USB port of the computer via the Micro USB cable, and release the button after the computer recognizes a removable hard disk (RPI-RP2).
Download the program and open D1-LED.ino under the arduino\PWM\D1-LED path
Click Tools --> Port, remember the existing COM, do not click this COM (the COM displayed is different on different computers, remember the COM on your own computer)
Connect the driver board to the computer using a USB cable. Then, go to Tools > Port. For the first connection, select uf2 Board. After uploading, when you connect again, an additional COM port will appear
Click Tools > Development Board > Raspberry Pi Pico > Corresponding models (Raspberry Pi Pico, Raspberry Pi Pico 2, etc.)
After setting it up, click the right arrow to upload the program

If issues arise during this period, and if you need to reinstall or update the Arduino IDE version, it is necessary to uninstall the Arduino IDE completely. After uninstalling the software, you need to manually delete all contents within the C:\Users\[name]\AppData\Local\Arduino15 folder (you need to show hidden files to see this folder). Then, proceed with a fresh installation.

Open Source Demos

MircoPython video demo (github)
MicroPython firmware/Blink demos (C)
Raspberry Pi official C/C++ demo (github)
Raspberry Pi official MicroPython demo (github)
Arduino official C/C++ demo (github)

Demo

C/C++ Demo

01_RS485

Demo description

This example implements the control of six relay switches through RS485

Code analysis

Relay_Control(): This function mainly executes the corresponding relay control operation and outputs the corresponding status prompt information according to the array index passed through the parameters
- Parameter analysis
  - uint8_t index: In the main function, the program will parse the received RS485 data and match it with the preset control command array. When a match is found, the Relay_Control function is called, and the index position of the matching command in the array is passed via index parameter
- Logical flow
  - Use the if else statement to perform different operations based on the value of index:
    - In the case of index < 6, that is, for the CH1~CH6 commands, the DEV_Digital_Write function is used to switch the level status of the corresponding GPIO pin (such as RELAY1_PIN, etc.), and at the same time, the corresponding relay_status array element is updated to record the change of the relay status, and the corresponding on or off prompt information is output according to the final state of the relay. Finally, in the main function, the Beep function is called to control the buzzer.
    - For the case of index = 6, i.e., for the ALL_ON command, all GPIO pins (corresponding to 6 channel relays) are set to high level (on state). Using the memset function, all elements of the relay_status array are set to 1, indicating that all relays are turned on. A message indicating that all relays are turned on is then output. Finally, in the main function, the Beep function is called to control the buzzer.
    - For the case of index = 7, i.e., for the ALL_OFF command, all GPIO pins (corresponding to 6 channel relays) will be set to low level (off state). Using the memset function, all elements of the relay_status array will be set to 0, indicating that all relays are off. A message indicating that all relays are off will be output. Finally, in the main function, the Beep function will be called to control the buzzer.
    - If the value of index does not match the above commands, the prompt message of receiving non-command data will be output

RS485 Control

Jump to RS485 Control Tutorial

02_MQTT

Demo description

This demo only supports the RP2350-Relay-6CH-W
This demo achieves network communication through a WiFi connection and remotely controls 6 relays via the MQTT protocol

Precautions

Devices need to be created in Waveshare Cloud
The following key parameters need to be modified:
- WiFi connection parameters:
  - WIFI_SSID: WiFi network name
  - WIFI_PASSWORD: WiFi password
- MQTT core parameters:
  - MQTT_CLIENT_ID: Device ID
  - MQTT_SERVER: Server address
  - MQTT_PUB_TOPIC: Release a topic
  - MQTT_SUB_TOPIC: Subscribe to a topic

Code analysis

Function description
- Relay_Init(): Initialize relay control GPIO
- start_client(): Create an MQTT client and connect to the server
- sub_unsub_topics(): Subscribe/unsubscribe from the topic
- mqtt_incoming_data_cb(): JSON message parsing and relay control core logic
Logical flow
- Device initialization:
  - Call Relay_Init() to initialize GPIO
  - Call cyw43_arch_wifi_connect_timeout_ms() to connect to WiFi
- MQTT connection:
  - Call mqtt_client_connect() to establish an MQTT connection
  - Call sub_unsub_topics() to subscribe to a control topic
- Control logic:
  - Receive JSON formatted messages (e.g., {data:{CH1:1}}) through the callback function mqtt_incoming_data_cb()
  - Parse channel name (CH1~CH6 or ALL) and control value (0/1)
  - Call gpio_put() to control the corresponding relay
  - After successfully controlling the relay, call mqtt_publish() to publish the update status to the MQTT server

Waveshare Cloud Control

Jump to Waveshare Cloud Control

03_BLE

Demo description

This demo only supports the RP2350-Relay-6CH-W
This demo achieves wireless communication via Bluetooth Low Energy (BLE) to remotely control 6 relays

Precautions

Device broadcast name: RP2350-Relay-6CH-W
Use custom UUID service: 0000FF01-0000-1000-8000-00805F9B34FB
Control command format: <channel name> <control value>

Code analysis

Function description
- Relay_Init(): Initialize relay control GPIO
- hci_power_control(): Turn on Bluetooth
- packet_handler(): Bluetooth protocol stack event handling core
- att_write_callback(): Command parsing and execution core logic
Logical flow
- Device initialization:
  - Call Relay_Init() to initialize relay GPIO
  - Call hci_power_control() to start the BLE protocol stack
- Establish connection:
  - Open the Bluetooth serial port tool, find the device broadcast name and UUID
  - Enable notification feature after client connection
- Control logic:
  - Receive text commands (e.g., CH1 1) in the callback function att_write_callback()
  - Parse channel name (CH1~CH6 or ALL) and control value (0/1)
  - Call gpio_put() to perform GPIO control
  - Return the operation result to the client through att_server_request_can_send_now_event()

Example of control commands

Open channel 1: CH1 1
Close channel 2: CH2 0
Open all channels: ALL 1
Close all channels: ALL 0

Example of error feedback

Invalid command: ERR: Cmd Invalid
Invalid channel: ERR: CH 1-6 Only
Invalid value: ERR: Need Value 0/1

MicroPython Demo

01_RS485

Demo description

This example implements the control of six relay switches through RS485

Code analysis

relay_control(): This function mainly executes the corresponding relay control operation and outputs the corresponding status prompt information according to the array index passed through the parameters
- Parameter analysis
  - index: In the main function, the program will parse the received RS485 data and match it with the preset control command array. When a match is found, the relay_control function is called, and the index position of the matching command in the array is passed via index parameter
- Logical flow
  - Use the if else statement to perform different operations based on the value of index:
    - In the case of index < 6, that is, for the CH1~CH6 commands, the relays[index].value function is used to switch the level status of the corresponding GPIO pin, and at the same time, the corresponding relay_status array element is updated to record the change of the relay status, and the corresponding on or off prompt information is output according to the final state of the relay. Finally, the beep function is called to control the buzzer.
    - For the case of index = 6, i.e., for the ALL_ON command, all GPIO pins (corresponding to 6 channel relays) are set to high level (on state), and all elements of the relay_status array are set to 1 through the for loop, indicating that all relays are turned on. A message indicating that all relays are turned on is then output. Finally, the beep function is called to control the buzzer.
    - For the case of index = 7, i.e., for the ALL_OFF command, all GPIO pins (corresponding to 6 channel relays) will be set to low level (off state). Using the for loop, all elements of the relay_status array will be set to 0, indicating that all relays are off. A message indicating that all relays are off will be output. Finally, the beep function will be called to control the buzzer.
    - If the value of index does not match the above commands, the prompt message of receiving non-command data will be output

RS485 Control

Jump to RS485 Control Tutorial

02_MQTT

Demo description

This demo only supports the RP2350-Relay-6CH-W
This demo achieves network communication through a WiFi connection and remotely controls 6 relays via the MQTT protocol

Precautions

Devices need to be created in Waveshare Cloud
Modify the following parameters in config.py:
- wifi_ssid: WiFi name
- wifi_password: WiFi password
- mqtt_client_id: Device ID
Modify the following parameters in main.py:
- MQTT_SUB_TOPIC: Subscribe to a topic
- MQTT_PUB_TOPIC: Release a topic

Code analysis

Function description
- initialize_wifi(): Connect to WiFi
- mqtt_connect(): Connect to MQTT
- mqtt_subscribe(): Subscribe to a topic
- mqtt_publish(): Publish message
- mqtt_recv_callback(): JSON message parsing and execution core
- init_relays(): Initialize all relays to the off state
- set_relay(): Control a single relay
- set_all_relays(): Control all relays
Logical flow
- Device initialization:
  - Call init_relays() to initialize all relays
- WiFi connection:
  - Call initialize_wifi() to connect to the specified network
- MQTT connection:
  - Call mqtt_connect() to connect to MQTT server
  - Call client.set_callback() to set the callback function
  - Subscribe to the topic MQTT_SUB_TOPIC via mqtt_subscribe()
- Control logic:
  - Call client.check_msg() in the main loop to wait for messages
  - Receive JSON formatted messages (e.g., {data:{CH1:1}}) through the callback function mqtt_recv_callback()
  - Parse channel name (CH1~CH6 or ALL) and control value (0/1)
  - Call set_relay() and set_all_relays() to achieve relay control
  - After successfully controlling the relay, call mqtt_publish() to publish the update status to the MQTT server

Waveshare Cloud Control

Jump to Waveshare Cloud Control

03_BLE

Demo description

This demo only supports the RP2350-Relay-6CH-W
This demo achieves wireless communication via Bluetooth Low Energy (BLE) to remotely control 6 relays

Precautions

Device broadcast name: RP2350-Relay-6CH-W
Use custom UUID service: 0000FF01-0000-1000-8000-00805F9B34FB
Control command format: <channel name> <control value>

Code analysis

Function description
- init_relays(): Initialize relay control GPIO
- bluetooth.BLE(): Initialize Bluetooth object
- BLERelayControl(): Bluetooth implements relay control
- _process_command(): Command parsing and execution core logic
Logical flow
- Device initialization:
  - Call init_relays() to initialize relay GPIO
  - Call bluetooth.BLE() to initialize Bluetooth object
  - Call BLERelayControl() to initialize Bluetooth controller
- Establish connection:
  - Open the Bluetooth serial port tool, find the device broadcast name and UUID
  - Enable notification feature after client connection
- Control logic:
  - Determine Bluetooth events through the callback function _irq()
  - Call the function _process_command() to receive text commands (e.g., CH1 1)
  - Parse channel name (CH1~CH6 or ALL) and control value (0/1)
  - Call _set_relay() and _set_all_relays() to achieve relay control
  - Return the operation result to the client through _send_response()

Example of control commands

Open channel 1: CH1 1
Close channel 2: CH2 0
Open all channels: ALL 1
Close all channels: ALL 0

Example of error feedback

Invalid command: ERR: Cmd Invalid
Invalid channel: ERR: CH 1-6 Only
Invalid value: ERR: Need Value 0/1

External Expansions

RS485 Extended Relay Channels

Use Modbus RTU Relay to extend 6-ch relay
Connect Modbus RTU Relay to the RS485 port of RP2350-Relay-6CH
The demo will turn on CH1~CH6 of Modbus-RTU-Relay one by one, and then turn them off one by one

Extend Timer Switch Function with Pico Port

Use Pico-RTC-DS3231 to extend timer switch function
Connect the Pico-RTC-DS3231 to the Pico port of RP2350-Relay-6CH
The demo will toggle all relay states every 5s

Extend CAN Port with Pico Port

Use Pico-CAN-B to extend CAN communication port
Connect Pico-CAN-B to the Pico port of RP2350-Relay-6CH
Power on after connecting Pico-CAN-B to USB-CAN-A
Data reception: Use USB-CAN-A_TOOL for debugging

Data transmission: Use the serial debugging assistant to view the printed data

Expand Environmental Monitoring Function

Use Pico-Environment-Sensor to extend environmental monitoring function
Connect Pico-Environment-Sensor to the Pico port of RP2350-Relay-6CH
The example will loop to monitor the environment and output the results

Extend RS485 Port with Pico Port

Please note, when using Pico-2CH-RS485 to expand the RS485 port, only channel 0 is supported, and channel 1 cannot be used
Connect Pico-2CH-RS485 to the Pico port of RP2350-Relay-6CH
Connect the channel 0 of Pico-2CH-RS485 to the Pico port of RP2350-Relay-6CH
The demo will perform data transmission and reception loopback testing to verify the data transmission and reception function of the on-board RS485 interface and the extended RS485 interface

Resources

Supporting Resources

Demo

Schematic Diagram

Schematic

Official Resources

Raspberry Pi Official Documents

Raspberry Pi Open Source Demos

Development Software

FAQ

Question: Raspberry Pi Pico 2 GPIO is configured as a pull-down input, why does reading IO show a high voltage level when the pin is left unconnected?

Answer:

You can refer to the RP2350-E9 section in the RP2350 Datasheet

Question: When controlling other devices using RS485, it is not sensitive or communication fails?

Answer:

Please move the jumper cap to 120R and try again. Some RS485 devices require a 120R resistor to be connected in series

Support

Technical Support

If you need technical support or have any feedback/review, please click the Submit Now button to submit a ticket, Our support team will check and reply to you within 1 to 2 working days. Please be patient as we make every effort to help you to resolve the issue.
Working Time: 9 AM - 6 PM GMT+8 (Monday to Friday)

Submit Now