i2c tools命令使用示例详解

i2cset：向i2c设备某个寄存器写入值

Usage: i2cset [-f] [-y] [-m MASK] [-r] [-a] I2CBUS CHIP-ADDRESS DATA-ADDRESS [VALUE] ... [MODE]
  I2CBUS is an integer or an I2C bus name
  ADDRESS is an integer (0x03 - 0x77, or 0x00 - 0x7f if -a is given)
  MODE is one of:
    c (byte, no value)
    b (byte data, default)
    w (word data)
    i (I2C block data)
    s (SMBus block data)
    Append p for SMBus PEC
    
    f:强制访问
    y:指令执行自动yes，否则会提示确认执行Continue? [Y/n] Y，不加参数y会有很多执行提示，可以帮助判断
    r:写入后立即回读寄存器的值，并将结果与写入的值进行比较
    i2cbus：总线编号
    chip-address:i2c设备地址
    data-address:i2c寄存器地址
    value 要写入的值
    mode：指定读取的大小，b字节，w字，s是SMBus块，i是i2c块

设置i2c-1上0x20器件的0x77寄存器值为0x3f
./i2cset -f -y 1 0x20 0x77 0x3f

i2cget：读取i2c设备某个寄存器的值

Usage: i2cget [-f] [-y] [-a] I2CBUS CHIP-ADDRESS [DATA-ADDRESS [MODE]]
  I2CBUS is an integer or an I2C bus name
  ADDRESS is an integer (0x03 - 0x77, or 0x00 - 0x7f if -a is given)
  MODE is one of:
    b (read byte data, default)
    w (read word data)
    c (write byte/read byte)
    Append p for SMBus PEC
    
    f:强制访问
    y:关闭交互模式，不会提示警告信息
    i2cbus:总线编号
    chip-address:i2c设备地址
    data-address:i2c寄存器地址
    mode:指定读取的大小，b字节，w字，s是SMBus块，i是i2c块

读取i2c-1上0x20器件的0x77寄存器值
./i2cget -f -y 1 0x20 0x77

i2cdump：读取某个i2c设备所有寄存器的值

Usage: i2cdump [-f] [-y] [-r first-last] [-a] I2CBUS ADDRESS [MODE [BANK [BANKREG]]]
  I2CBUS is an integer or an I2C bus name
  ADDRESS is an integer (0x03 - 0x77, or 0x00 - 0x7f if -a is given)
  MODE is one of:
    b (byte, default)
    w (word)
    W (word on even register addresses)
    s (SMBus block)
    i (I2C block)
    c (consecutive byte)
    Append p for SMBus PEC
    
    r:指定寄存器范围，只能扫描从 first 到 last 区域
    f:强制访问设备
    y:关闭人机交互模式
    i2cbus:总线编号
    address:指定设备地址
    mode:指定读取的大小，b字节，w字，s是SMBus块，i是i2c块

读取i2c1上0x38器件的所有寄存器
./i2cdump -f -y -a 1 0x38

一般寄存器都是8位地址的，i2cdump、i2cget、i2cset 也是设置读取8位的地址，如果一次超过8位，需要用 i2ctransfer。

i2ctransfer：一次性读写多个字节

Usage: i2ctransfer [-f] [-y] [-v] [-V] [-a] I2CBUS DESC [DATA] [DESC [DATA]]...
  I2CBUS is an integer or an I2C bus name
  DESC describes the transfer in the form: {r|w}LENGTH[@address]
    1) read/write-flag 2) LENGTH (range 0-65535) 3) I2C address (use last one if omitted)
  DATA are LENGTH bytes for a write message. They can be shortened by a suffix:
    = (keep value constant until LENGTH)
    + (increase value by 1 until LENGTH)
    - (decrease value by 1 until LENGTH)
    p (use pseudo random generator until LENGTH with value as seed)

查看系统上存在的 i2c 总线及其设备地址

ls /sys/bus/i2c/devices/

可以在这里查看实际的设备，然后对比 i2c-tools 扫描出来的对不对。