Source Code Location

The utility suite is often found within the toybox repository in Android-based environments:

android/external/toybox/toys/other/i2ctools.c

Available Utilities

The compiled binary provides four distinct commands for enteracting with the I2C subsystem:

• i2cdetect: Scans a specific bus to identify connected slave addresses.
• i2cdump: Displays a hex dump of the registers on a target device.
• i2cget: Reads a single byte or word from a specific register.
• i2cset: Writes data to a specific register address on a device.

Verifying Installation

Check if the binaries are present on your system using shell auto-completion:

console:/ # i2c<TAB>
i2cdetect  i2cdump    i2cget     i2cset

Identifying Active Buses

List the available I2C adapters recognized by the kernel. These typically appear as i2c- followed by a number:

console:/ # ls -l /dev/i2c-*
crw------- 1 root root 89,  3  /dev/i2c-3
crw------- 1 root root 89,  5  /dev/i2c-5

Scanning Addresses with i2cdetect

Use i2cdetect to probe a bus (e.g., bus 3) and find active device addresses. The following example scans the full range (0x00-0x7f) and finds a device at address 0x1e.

console:/ # i2cdetect --help
usage: i2cdetect [-ary] BUS [FIRST LAST]
...

console:/ # i2cdetect -a 3
Probe chips 0x00-0x7f on bus 3? (Y/n): y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1e --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
...
70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

Writing Data with i2cset

The i2cset command allows you to modify register values. The syntax generally follows: i2cset -y [BUS] [DEVICE_ADDR] [REG_ADDR] [VALUE] [MODE].

Supported modes include:

• b: Byte (8-bit)
• w: Word (16-bit)
• i: I2C block data

console:/ # i2cset --help
usage: i2cset [-fy] BUS CHIP ADDR VALUE... MODE
...

console:/ # i2cset -y 3 0x1E 0x00 0x3 b

Reading Data with i2cget

To verify the write operation, use i2cget to read back the value from register 0x00. The output confirms the value 0x03 was successfully stored.

console:/ # i2cget --help
usage: i2cget [-fy] BUS CHIP ADDR
...

console:/ # i2cget -y 3 0x1E 0x00
0x03

Dumping Registers with i2cdump

For a comprehensive view of the device state, i2cdump reads consecutive registers. Below is a dump of the devicce at 0x1e on bus 3:

console:/ # i2cdump -y 3 0x1E
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 03 00 00 02 02 01 ee ee 00 80 00 00 00 00 00 00    ?..?????.?......
10: 00 01 00 03 ee ee ee ee ee 40 00 00 ff ff ee ee    .?.??????@..????
20: 05 13 01 00 00 ee ee ee 00 00 00 80 00 80 ee ee    ???..???...?.???
30: 00 00 ee 05 ee 00 ee 1b 00 00 00 00 00 00 00 00    ..???.??........
40: 82 84 80 93 80 8f 86 80 ee ee ee ee ee ee ee ee    ????????????????
50: ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee    ????????????????
...
f0: ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee    ????????????????