I2C

The Inter-Integrated Circuit (I2C) interface is a two-wire, bidirectional serial bus that provides a simple and efficient method for data exchange among devices. The phyCORE-AM62Px provides independent multimaster fast-mode I2C modules. This guide will show you how to test the I2C interface on the phyBOARD-Lynx AM62Px. To learn more information about the phyCORE-AM62Px I2C interface, please see the I2C section in the Hardware Manual.

Note

Only a subset of I2C interfaces are supported on the phyBOARD-Lynx AM62Px by default but others can be enabled via pin multiplexing.

I2C Settings

Hardware Interface

sysfs Path

WKUP_I2C0

/dev/i2c-0

I2C0

/dev/i2c-1

I2C1

/dev/i2c-2

Scanning the I2C Buses

  • Power on the phyBOARD-Lynx AM62Px and boot into Linux.

  • List the available I2C devices. Each /dev/i2c-* entry corresponds to one of the I2C interfaces in the table above.

List I2C devices
phyboard-lynx-am62pxx-1:~# ls /dev/i2c*

  • Use the i2cdetect command to scan each bus for devices. WKUP_I2C0 carries the SOM’s own devices (PMIC, EEPROMs, RTC). I2C0 is exposed on the X28 expansion header and has no carrier-board devices by default. I2C1 carries the carrier-board peripherals.

Scan WKUP_I2C0 bus (SOM devices)
phyboard-lynx-am62pxx-1:~# i2cdetect -y -r 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: UU UU UU -- -- -- -- -- 58 59 -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
Scan I2C0 bus (X28 expansion header, no devices populated)
phyboard-lynx-am62pxx-1:~# i2cdetect -y -r 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
Scan I2C1 bus (carrier board devices)
phyboard-lynx-am62pxx-1:~# i2cdetect -y -r 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: 10 -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
20: UU UU -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- --
40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- UU -- -- -- -- 56 -- -- 59 -- -- -- -- -- --
60: -- -- 62 -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Note

UU indicates that the device with that particular address is tied to a kernel driver and you will be unable to communicate with the device via i2c commands (i2cset and i2cget).

The detected interfaces on WKUP_I2C0 and I2C1 correspond to:

WKUP_I2C0 addresses (SOM devices)

Interface

Address (7-bit)

Reference

PMIC TPS65219

0x30

U6

VDD_CORE Regulator

0x40

U7

PHYTEC EEPROM

0x50

U8

Customer EEPROM

0x51

U9

RTC

0x52

U11

PHYTEC EEPROM identification page

0x58

U8

Customer EEPROM identification page

0x59

U9
I2C1 addresses (carrier board devices)

Interface

Address (7-bit)

Reference

Light Sensor VEML6030

0x10

U57

Audio Codec TLV320AIC3212

0x18

U55

GPIO Expander TCA6416A

0x20

U73

GPIO Expander TCA6416A

0x21

U74

HDMI Transmitter SiI9022A

0x3B

U47

EEPROM M24C32

0x51

U76

HDMI CEC Transmitter SiI9022A

0x62

U47

Note

The list of visible I2C devices in your output may differ from what is shown above. This is because our System on Modules (SoMs) come in different variants, and some devices (like the RTC) are optional depending on the specific variant you are using.