Hardware (I2C / SPI)

Use the i2c and spi tools to interact with sensors, displays, and other peripherals connected to the board.

Quick Start

# 1. Find available buses
i2c detect

# 2. Scan for connected devices
i2c scan  (bus: "1")

# 3. Read from a sensor (e.g. AHT20 temperature/humidity)
i2c read  (bus: "1", address: 0x38, register: 0xAC, length: 6)

# 4. SPI devices
spi list
spi read  (device: "2.0", length: 4)

Before You Start — Pinmux Setup

Most I2C/SPI pins are shared with WiFi on Sipeed boards. You must configure pinmux before use.

See references/board-pinout.md for board-specific commands.

Common steps:

1. Stop WiFi if using shared pins: /etc/init.d/S30wifi stop
2. Load i2c-dev module: modprobe i2c-dev
3. Configure pinmux with devmem (board-specific)
4. Verify with i2c detect and i2c scan

Safety

• Write operations require confirm: true — always confirm with the user first
• I2C addresses are validated to 7-bit range (0x03-0x77)
• SPI modes are validated (0-3 only)
• Maximum per-transaction: 256 bytes (I2C), 4096 bytes (SPI)

Common Devices

See references/common-devices.md for register maps and usage of popular sens…