This page shows the basic usage of the I2C bus.
the following examples are using an external GPIO expander.
i2cdetect is used to identify available I2C devices on a given I2C bus. An overview of the available I2C busses can be achieved by using i2cdetect -l
test@test-desktop:~$ i2cdetect -l
i2c-3 i2c 3190000.i2c I2C adapter
i2c-1 i2c c240000.i2c I2C adapter
i2c-101 i2c 15210000.nvdisplay I2C adapter
i2c-8 i2c 31e0000.i2c I2C adapter
i2c-6 i2c 31c0000.i2c I2C adapter
i2c-4 i2c Tegra BPMP I2C adapter I2C adapter
i2c-2 i2c 3180000.i2c I2C adapter
i2c-0 i2c 3160000.i2c I2C adapter
i2c-9 i2c i2c-2-mux (chan_id 0) I2C adapter
i2c-10 i2c i2c-2-mux (chan_id 1) I2C adapter
i2c-7 i2c c250000.i2c I2C adapter
i2c-5 i2c 31b0000.i2c I2C adapter--: No device found
21: There is a device on address 0x21
UU: A Linux driver is currently using this device
Syntax: i2cdetect [options] <busNr>
test@test-desktop:~$ i2cdetect -y -r 2
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 21 -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
test@test-desktop:~$ The ì2cdump operation is good tool to see the content of a given I2C device to get a better overview of the stored data in its registers.
Syntax: i2cdump [options] <busNr> <deviceAddress>
test@test-desktop:~$ i2cdump -y -f 2 0x21
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: 2c ff 00 ff XX XX XX XX XX XX XX XX XX XX XX XX ,...XXXXXXXXXXXX
10: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
20: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
30: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
40: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
50: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
60: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
70: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
80: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
90: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
a0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
b0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
c0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
d0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
e0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
f0: XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXXXXXXXXXXXXXXX
i2cget is used for reading a byte value from a given device I2C register address.
Syntax: i2cget [options] <busNr> <deviceAddress> <register> <address>
test@test-desktop:~$ sudo i2cget -y -f 2 0x21 0x03 0x00
0x00
test@test-desktop:~$i2cset is used for writing a byte value to a given device I2C register address.
Syntax: i2cset [options] <busNr> <deviceAddress> <register> <address> <value>
test@test-desktop:~$ sudo i2cset -y -f 2 0x21 0x03 0xff
test@test-desktop:~$ sudo i2cget -y -f 2 0x21 0x03 0x00
0xffThis guide provides the basic usage of I2C devices that are often used on our Carrierboards.
1.0
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1.1
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I2C (Inter-Integrated Circuit) is a two wire communication protocol that is used to read and write data to peripherals devices form one master system (In our case the Jetson Module). It is commonly used in embedded hardware due to its simplicity & low power communication between components.
This protocol is used on our hardware for several devices such as:
Camera sensors
Temperature sensors
IMU's
GPIO Port extender
and so on...