README.md

air-gradient-pro-rs

Firmware and tools for the AirGradient PRO kit with some modifications.

The firmware is written in Rust and uses the RTIC framework.

Overview

I've modified an AirGradient PRO kit (PCB Version 3.7) mainly so I can have a wired ethernet connection.

Significant differences from stock:

• Replace the Wemos D1 Mini v4 with an stm32f411 "black pill" board
• Add a ENC28J60 Ethernet board
• Custom Rust firmware

Features

• TCP/IP stack, comes with a lightweight broadcast protocol
• CLI with command-line tools and InfluxDB relaying, see the air-gradient-cli README
• Configuration for network and device settings
• OLED display

Configuration

The build.rs file handles generating build-time configuration values based on the github repository and host environment variables.

The following environment variables can be set:

• AIR_GRADIENT_IP_ADDRESS : The deivce's IP address, default is 192.168.1.38
• AIR_GRADIENT_MAC_ADDRESS : The device's MAC address, default is 02:00:04:03:07:02
• AIR_GRADIENT_DEVICE_ID : An arbitrary 16-bit identifier, default is 0xFFFF (DeviceId::DEFAULT)
• AIR_GRADIENT_BROADCAST_PORT : The port number to send the broadcast protocol data on, default is 32100
• AIR_GRADIENT_BROADCAST_ADDRESS : The IP address to send the broadcast protocol data to, default is 255.255.255.255

Flashing

Flashing the board is currently done via SWD and an st-link.

You can use the Development Artifacts github action to build a custom-configured firmware image in CI (click "Run workflow" and set the configuration fields) or grab the latest release with the default configuration from the Releases page.

Using a github release artifact

1. Install probe-rs-cli

cargo install probe-rs-cli

2. Flash the target

probe-rs-cli run --chip STM32F411CEUx --protocol swd path/to/air-gradient-pro

Building from source

1. Install cargo-embed and flip-link

cargo install cargo-embed flip-link

2. Build the firmware and flash the target

cargo embed --release

Log messages are available on pin PA11 (USART6 Tx), you should see output like the following:

[I] ############################################################
[I] air-gradient-pro-rs 0.1.0 (release)
[I] Build date: Fri, 07 Apr 2023 10:00:13 +0000
[I] rustc 1.68.2 (9eb3afe9e 2023-03-27)
[I] git commit: 709ce69ea2a86585e58f07684f0def66e5f79010
[I] Serial number: 303233313036517042018
[I] Device ID: 0x1 (1)
[I] IP address: 192.168.1.38
[I] MAC address: 02-00-04-03-07-02
[I] Broadcast protocol port: 32100
[I] Broadcast protocol address: 255.255.255.255
[I] ############################################################
[I] Setup: startup delay 5 seconds
[I] Setup: S8 LP
[I] Setup: PMS5003
[I] Setup: I2C2
[I] Setup: SH1106
[I] Setup: SHT31
[I] Setup: SGP41
[I] Setup: ETH
[I] Setup: TCP/IP
[I] Setup: net clock timer
[I] Setup: net poll timer
[I] >>> Initialized <<<

Hardware

• STM32F411 "black pill"
  • WeActStudio github
  • pinout diagram
  • refman
  • datasheet
• ENC28J60 Ethernet board
  • Waveshare wiki
  • datasheet
• AirGradient PRO V3.7 kit
  • kit page
  • schematic
  • Arduino code github
  • Factory firmware
• SH1106 OLED
  • datasheet
• Sensirion SHT31 (temperature/humidity sensor)
  • datasheet
• Senseair S8 LP (CO2 sensor)
  • product page
  • doc
  • doc
• PMS5003 (particle concentration sensor)
  • manual
• Sensirion SGP41 (TVOC/NOx sensor)
  • product page
  • datasheet

Pins

Pin	Peripheral	Board D1 Mini Header Pin	Description
PA11	USART6 Tx	TX	Console/logger/panic-handler output
PA12	USART6 Rx	RX	Console input
PA9	USART1 Tx	D3	senseAir S8 Rx
PA10	USART1 Rx	D4	senseAir S8 Tx
PA2	USART2 Tx	D6	PMS5003 Rx
PA3	USART2 Rx	D5	PMS5003 Tx
PB3	I2C2 SDA	D1	Shared I2C SCL : SH1106, SHT31, SGP41
PB10	I2C2 SCL	D2	Shared I2C SDA : SH1106, SHT31, SGP41
PB13	SPI2 SCK	NC	ENC28J60 Eth SCK
PB14	SPI2 MISO	NC	ENC28J60 Eth MISO
PB15	SPI2 MOSI	NC	ENC28J60 Eth MOSI
PB12	GPIO Output	NC	ENC28J60 Eth CS
PA8	GPIO Input	NC	ENC28J60 Eth INT
PB1	GPIO Output	NC	ENC28J60 Eth RESET
PC13	GPIO Output	NC	On-board LED