Complete technical content from Chinese RK-KF-YF-113 V1.0.2. The source covers RK2108/Pisces with RT-Thread 3.1.3. No matching ArmSoM board combination is confirmed, so this is a platform reference: check the SoC, RT-Thread BSP, bus numbers, pin multiplexing, voltage domain and pull-ups before use. This is not Linux I2C configuration or universal board support. Only a Chinese source exists, with no standalone technical figures. English, Russian and German fully translate the text while preserving configuration and original code comments. No hardware validation was performed.
1. Functional configuration
I2C configuration has two parts: the driver framework and VENDOR settings. Enable the required I2C buses as below. All buses may be enabled, at the cost of a little extra memory.
# I2C驱动框架
RT_USING_I2C [=y]
# VENDOR驱动，根据需求启用你需要的I2C总线，也可以全开，只是会浪费一点点的内存
RT_USING_I2C0 [=y]
RT_USING_I2C1 [=y]
RT_USING_I2C2 [=y]
2. Board configuration
The RK2108 and Pisces I2C IO pins are multiplexed. Ensure that IOMUX switches the relevant pins to I2C mode. See the IOMUX chapter of the Rockchip RT-Thread development guide. The original PDF link to that guide is an incomplete relative address; no website article URL has been invented.
3. Development guide
The Rockchip I2C driver follows the standard RTT I2C driver framework. Refer directly to the official RTT I2C development guide.