i2cset - set I2C registers

bionic (8) i2cset.8.gz

Provided by: i2c-tools_4.0-2_amd64 
 

NAME

       i2cset - set I2C registers

SYNOPSIS

       i2cset [-f] [-y] [-m mask] [-r] i2cbus chip-address data-address [value] ...  [mode]
       i2cset -V

DESCRIPTION

       i2cset is a small helper program to set registers visible through the I2C bus.

OPTIONS

       -V     Display the version and exit.

       -f     Force  access  to  the  device  even if it is already busy. By default, i2cset will
              refuse to access a device which is already under the control of  a  kernel  driver.
              Using  this  flag  is  dangerous,  it  can  seriously  confuse the kernel driver in
              question. It can also cause i2cset to silently write to the wrong register. So  use
              at your own risk and only if you know what you're doing.

       -y     Disable  interactive mode. By default, i2cset will wait for a confirmation from the
              user before messing with the I2C bus. When this flag is used, it will  perform  the
              operation directly. This is mainly meant to be used in scripts.

       -m mask
              The  mask  parameter,  if specified, describes which bits of value will be actually
              written to data-address. Bits set to 1 in the mask are taken from value, while bits
              set to 0 will be read from data-address and thus preserved by the operation. Please
              note that this parameter assumes  that  the  read  and  write  operations  for  the
              specified  mode  are  symmetrical for the device you are accessing. This may or may
              not be the case, as neither I2C nor SMBus guarantees this.

       -r     Read back the value right after writing it, and compare the result with  the  value
              written.  This used to be the default behavior. The same limitations apply as those
              of option -m.

       There are three required options to i2cset. i2cbus indicates the number or name of the I2C
       bus to be scanned.  This number should correspond to one of the busses listed by i2cdetect
       -l. chip-address specifies the address of the chip on that bus, and is an integer  between
       0x03  and  0x77.   data-address  specifies the address on that chip to write to, and is an
       integer between 0x00 and 0xFF.

       The value parameter, if specified, is the value to write to that location on the chip.  If
       this parameter is omitted, then a short write is issued. For most chips, it simply sets an
       internal pointer to the target location, but doesn't actually write to that location.  For
       a  few chips though, in particular simple ones with a single register, this short write is
       an actual write. If the mode parameter is s or i, multiple values can be specified.

       The mode parameter, if specified, is one of the letters b, w, s, or i, corresponding to  a
       write  size  of  a single byte, a 16-bit word, a SMBus block write, or an I2C block write,
       respectively.  For SMBus and I2C block writes, the write size is determined by the  number
       of  value  parameters.   Except for I2C block writes, a p can also be appended to the mode
       parameter to enable PEC.  If the mode parameter is omitted, i2cset defaults to  byte  mode
       without  PEC.  The  value  provided  must  be  within  range  for  the specified data type
       (0x00-0xFF for byte and block writes, 0x0000-0xFFFF for words).  Another possible mode  is
       c,  which  doesn't  write  any  value  (so-called  short write). You usually don't have to
       specify this mode, as it is the default when no value is provided, unless you also want to
       enable PEC.

WARNING

       i2cset  can  be extremely dangerous if used improperly. It can confuse your I2C bus, cause
       data loss, or have more serious side effects. Writing to a serial EEPROM on a memory  DIMM
       (chip  addresses  between  0x50  and  0x57)  may  DESTROY your memory, leaving your system
       unbootable!  Be extremely careful using this program.

EXAMPLES

       Write value 0x42 to 8-bit register 0x11 of the I2C device at 7-bit address 0x2d on  bus  1
       (i2c-1), after user confirmation:
              # i2cset 1 0x2d 0x11 0x42

       Immediately clear the 3 least significant bits of 8-bit register 0x11 of the I2C device at
       7-bit address 0x2d on bus 1 (i2c-1) (no user confirmation):
              # i2cset -y -m 0x07 1 0x2d 0x11 0x00

       Write value 0x5000 to 16-bit register 0x02 of the I2C device at 7-bit address 0x48 on  bus
       1 (i2c-1), after user confirmation:
              # i2cset 1 0x48 0x02 0x5000 w

       Also see i2cget(8) for examples of combined usage of i2cset and i2cget.

SEE ALSO

       i2cdetect(8), i2cdump(8), i2cget(8), i2ctransfer(8), isaset(8)

AUTHOR

       Frodo Looijaard, Mark D. Studebaker and Jean Delvare

       This  manual page was originally written by David Z Maze <dmaze@debian.org> for the Debian
       GNU/Linux system.

                                           October 2017                                 I2CSET(8)

///////////////////////////////////////////////////////////////////////////////

How to write to a 16-bit I2C address using i2cset

Trying to write a byte to a 16-bit address on an I2C device (OV5640 camera) using i2cset. I can successfully read from the device registers using the following sequence (read byte from device address 0x3c and register address 0x3030): 'i2cset -v -f 1 0x3c 0x30 0x30' 'i2cget -v -f 1 0x3c'

To write to the device, I use this sequence (write byte 0x40 to device address 0x3c and register address 0x3030): 'i2cset -v -f 1 0x3c 0x30 0x30' 'i2cset -v -f 1 0x3c 0x40' This sequence does not show any errors but when the address is read again, the value is unchanged. Can anyone provide any insight on the correct i2cset syntax to use when writing to this device? Thanks for you input.

读寄存器地址:(register address 0x3030），iic总线1，设备地址0x3c：

        i2cset -v -f 1 0x3c 0x30 0x30

        i2cget -v -f 1 0x3c

尝试写寄存器地址(register address 0x3030），iic总线1，设备地址0x3c，写入值：0x40：

        i2cset -v -f 1 0x3c 0x30 0x30     注：即是先写地址，在写值    无法写入

        i2cset -v -f 1 0x3c 0x40

1

• Your title seems a bit off. I2C addresses are either 7-bit or 10-bit. You seem to mean address of register inside this I2C device? Are you sure your write sequence is correct. Without looking at the datasheet (which you should paste the relevant info from), it seems to be it should be something like i2cset -v -f 1 0x3c 0x30 0x30 0x40 (one write, instead of two writes). – domen Oct 9 '20 at 9:04

1 Answer

 

 

SOLVED! I found the solution for this and it requires using the i2cset block write option (i) as follows: i2cset -y -f 2 0x3c 0x30 0x30 0x40 i

This command writes the value 0x40 to register address 0x3030 at device address 0x3c.

成功的方法：

尝试写寄存器地址(register address 0x3030），iic总线1，设备地址0x3c，写入值：0x40：

        i2cset -y -f 2 0x3c 0x30 0x30 0x40 i