I2C

UBOOT 下 I2C

在UBOOT下测试硬件是否正常

确认UBOOT中对I2C支持,一般会有相应命令

uboot # i2c
i2c - I2C sub-system

Usage:
i2c crc32 chip address[.0, .1, .2] count - compute CRC32 checksum
i2c dev [dev] - show or set current I2C bus
i2c loop chip address[.0, .1, .2] [# of objects] - looping read of device
i2c md chip address[.0, .1, .2] [# of objects] - read from I2C device
i2c mm chip address[.0, .1, .2] - write to I2C device (auto-incrementing)
i2c mw chip address[.0, .1, .2] value [count] - write to I2C device (fill)
i2c nm chip address[.0, .1, .2] - write to I2C device (constant address)
i2c probe [address] - test for and show device(s) on the I2C bus
i2c read chip address[.0, .1, .2] length memaddress - read to memory
i2c write memaddress chip address[.0, .1, .2] length - write memory to i2c
i2c reset - re-init the I2C Controller
i2c speed [speed] - show or set I2C bus speed

查看当前使用的I2C BUS

uboot # i2c dev
Current bus is 0

查询该总线下接的所有I2C设备

uboot # i2c probe
Valid chip addresses: 14 40 41 51 55 5A

如果是下面这样的输出,则说明该总线有异常,极大可能是有I2C设备拉低了总线

uboot # i2c probe
Valid chip addresses:I2C Send Start Bit Timeout
I2C Send Start Bit Timeout

切换I2C BUS

uboot # i2c dev 1
Setting bus to 1