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3.1.5 Using I2C

By default, RDK X3 enables I2C0 on pin 40, with physical pin numbers 3 and 5, and IO voltage of 3.3V.

By default, RDK X5 enables I2C5 (physical pin numbers 3 and 5) and I2C0 (physical pin numbers 27 and 28) on pin 40, and IO voltage of 3.3V.

RDX Ultra enables I2C4 and I2C6, with physical pin numbers 3, 5, 27, and 28, and IO voltage of 3.3V.

Please refer to /app/40pin_samples/test_i2c.py for detailed information on how to use I2C.

Testing Method​

  • Run the test program python3 /app/40pin_samples/test_i2c.py

  • List the currently enabled I2C buses

  • Scan the bus to see which devices are connected to the bus by inputting the bus number

  • Input the device address (in hexadecimal), and the test program will read one byte of data from that device

Test Result​

Starting demo now! Press CTRL+C to exit
List of enabled I2C controllers:
/dev/i2c-0  /dev/i2c-1
Please input I2C BUS num:1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- -- 
40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
Please input I2C device num(Hex):40
Read data from device 40 on I2C bus 1
read value= b'`'

Test Code​

#!/usr/bin/env python3

import sys
import os
import time

# import i2cdev
from i2cdev import I2C

def i2cdevTest():
    # device, bus = 0x51, 0
    bus = input("Please input I2C BUS num:")
    os.system('i2cdetect -y -r ' + bus)
    device = input("Please input I2C device num(Hex):")
    print("Read data from device %s on I2C bus %s" % (device, bus))
    i2c = I2C(eval("0x" + device), int(bus))
    value = i2c.read(1)
    i2c.write(value)
    print("read value=", value)
    i2c.close()

if __name__ == '__main__':
    signal.signal(signal.SIGINT, signal_handler)
    print("Starting demo now! Press CTRL+C to exit")
    print("List of enabled I2C controllers:")
    os.system('ls /dev/i2c*')
    while True:
        i2cdevTest()

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