Using I2C in Linux
- Albinleo Velappan (Deactivated)
Using I2C in Linux
The Trizeps and Myon CPU modules may be configured to have multiple I2C busses.
Myon I
Pins | IO-Port | Driver Index | Description |
|---|---|---|---|
66,68 | I2C4 | 3 | typical connected to touch-controller |
119,121 | I2C6 | 5 | I2C devices |
Trizeps VII
Pins | Port | Driver Index | Description |
|---|---|---|---|
194,196 | I2C2 | 1 | primary I2C interface |
94,96 | I2C1 | 0 | secondary I2C interface |
The PMFP0100 PMIC (7-bit address 0x08) of the Trizeps VII is connected to the primary I2C interface.
Trizeps VIII
Pins | Port | Driver Index | Description |
|---|---|---|---|
194,196 | I2C2 | 1 | primary I2C interface |
94,96 | I2C1 | 0 | secondary I2C interface |
- | I2C3 | 2 | internal I2C interface |
The following devices are attached to the internal I2C interface:
7bit | 8bit | Description |
|---|---|---|
0x08 | 0x10 | PMFP0100 PMIC |
0x10 | 0x20 | MKV11 Kinetis MCU |
0x1A | 0x34 | WM8983 Audio Codec |
0x2C | 0x58 | MIPI to LVDS transceiver |
0x40 | 0x80 | FPGA primary config address |
0x41 | 0x82 | FPGA primary user mode |
0x42 | 0x84 | FPGA secondary user mode |
0x43 | 0x86 | FPGA primary config reset |
0x60 | 0xC0 | VDD_SOC regulatur |
Trizeps VIII Mini
Pins | Port | Driver Index | Description |
|---|---|---|---|
194,196 | I2C2 | 1 | primary I2C interface |
94,96 | I2C1 | 0 | secondary I2C interface |
- | I2C3 | 2 | internal I2C interface |
The following devices are attached to the internal I2C interface:
7bit | 8bit | Description |
|---|---|---|
0x10 | 0x20 | MKV11 Kinetis MCU |
0x1A | 0x34 | WM8983 Audio Codec |
0x2C | 0x58 | MIPI to LVDS transceiver |
0x40 | 0x80 | FPGA primary config address |
0x41 | 0x82 | FPGA primary user mode |
0x42 | 0x84 | FPGA secondary user mode |
0x43 | 0x86 | FPGA primary config reset |
0x4B | 0x96 | BD71847 PMIC |
Trizeps VIII Plus
Pins | Port | Driver Index | Description |
|---|---|---|---|
194,196 | I2C2 | 1 | primary I2C interface |
94,96 | I2C1 | 0 | secondary I2C interface |
- | I2C3 | 2 | internal I2C interface |
The following devices are attached to the internal I2C interface:
7bit | 8bit | Description |
|---|---|---|
0x10 | 0x20 | MKV11 Kinetis MCU |
0x1A | 0x34 | WM8983/WM8962B Audio Codec |
0x25 | 0x4A | PCA9450 PMIC |
0x40 | 0x80 | FPGA primary config address |
0x41 | 0x82 | FPGA primary user mode |
0x43 | 0x86 | FPGA primary config reset |
0x4A | 0x94 | WM8962B test functionality |
0x69 | 0xD2 | WM8962B test functionality |
0x78 | 0xF0 | ??? |
Myon II
Pins | Port | Driver Index | Description |
|---|---|---|---|
J70-66,68 | I2C2 | 1 | primary I2C interface |
J71-67,69 | I2C1 | 0 | secondary I2C interface |
J71-19,21 | I2C3 | 2 | internal I2C interface |
[J70-73,75] | I2C4 | 3 | special mounting option! |
The following devices are attached to the internal I2C interface:
7bit | 8bit | Description |
|---|---|---|
0x1A | 0x34 | WM8983 Audio Codec |
0x2C | 0x58 | MIPI to LVDS transceiver |
0x4B | 0x96 | BD71847 PMIC |
SBCSOM
Pins | Port | Driver Index | Description |
|---|---|---|---|
L.A04,A05 | I2C1 | 0 | left connector, i-MOD I2C, Mini-PCIe socket |
R.A04,A05 | I2C2 | 1 | right connector, camera , KuK-MODIS |
– | I2C3 | 2 | internal I2C interface |
The following devices are attached to the internal I2C interface:
7bit | 8bit | Description |
|---|---|---|
0x1A | 0x34 | WM8983 Audio Codec |
0x2C | 0x58 | MIPI to LVDS transceiver |
0x39 | 0x72 | HDMI transceiver |
0x49 | 0x92 | Secure Element |
0x4B | 0x96 | BD71847 PMIC |
0x50 | 0xA0 | EEPROM |
Use I2C from the Command Line
Please view the man-pages of the commands for details. The below instructions are only for a quick reference. On Debian, these tools are contained in the package i2c-tools. Install it with:
sudo apt install i2c-toolsScan for available I2C devices
In this example we scan the internal I2C interface of Trizeps VIII.
$ i2cdetect -y 2Which will output:
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- 08 -- -- -- -- -- -- --
10: 10 -- -- -- -- -- -- -- -- -- 1a -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: 40 UU -- 43 -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
The '-y' option is used to prevent the 'Continue? [Y/n]' question.
'2' is the Driver-Index of the I2C3 interface.
The output shows the found I2C-devices. 'UU' indicates that a driver for this device has been loaded. In the above case it is a driver that communicates with the Trizeps VIII FPGA.
Read from I2C device
In this example outputs the ID-register of the Trizeps VIII FPGA (depends on FPGA programming):
The '-f' option forces access to device 0x41. This is used, because a driver for this address has already been loaded and will prevent access without the force option.
The '-y' option is used to prevent the 'Continue? [Y/n]' question.
'2' is the Driver-Index of the I2C3 interface.
'0x41' is the 7bit I2C-address of the Trizeps VIII FPGA. '0' is the ID-register offset.
Write to I2C device
This will write to register 0x10 of device connected to 0x41. In this specific case it disables conversion of the MIPI-DSI stream.
The '-f' option forces access to device 0x41. This is used, because a driver for this address has already been loaded and will prevent access without the force option.
The '-y' option is used to prevent the 'Continue? [Y/n]' question.
'2' is the Driver-Index of the I2C3 interface.
'0x41' is the 7bit I2C-address of the Trizeps VIII FPGA. '0x10' is the display control register.
Other I2C Commands
'i2ctransfer' may be used to have better control on how an I2C packet is sent (Multiple bytes write & read).
'i2cdump' may be used to dump registers of an I2C device.