I2C slave emulation using GPIOs

This slave will respond to any address. The lib is designed to work with GPIOs which uses INPUT to achieve open-drain. This means that lines are requested as input to drive a 1 on the line, and output to low to drive a 0.

Usage

i2c-slave-gpio <gpiochip> <scl> <sda>

gpiochip: char device (e.g. /dev/gpiochip0)
sda: sda gpio line (e.g. 0)
scl: scl gpio line (e.g. 1)

To enable logs, you need to pass the env variable RUST_LOG=<debug,info,warn,error>.

To use this slave, you need to enable GPIO support for your platform (since linux 5, char device is exposed by default for GPIO). To use the I2C char device, you need to enable char device support with

CONFIG_I2C_CHARDEV=y

in your kernel compile options

Building

cargo build

YOCTO

You can produce a YOCTO receipe using cargo bitbake.

cargo install --locked cargo-bitbake
cargo bitbake

This will generate a file i2c-slave-gpio_<ver>.bb.

Then in your list of packages add i2c-slave-gpio

PACKAGE_INSTALL:append = " \
    i2c-tools \ # usefull for testing purposes (i2cset, i2cget)
    i2c-slave-gpio \
"