4.10 EEPROM Test

This example demonstrates how to use Linux API to read and write the EEPROM of MYD-C437X-PRU development board, please refer the source code for detail.

Hardware Preparation:

  • One MYD-C437X-PRU development board
  • One USB to TTL converter used to connect J25 of MYD-C437X-PRU development board and host PC, set the baudrate of serial port on host PC to 115200-8-n-1
  • Make sure a EEPROM IC 24256E is soldered on the MYD-C437X-PRU development board

Software Preparation:

  • Linux Kernel 4.1.18
  • eeprom_test application

Test Steps:

  • Copy cross compiled <WORKDIR>/Examples/eeprom/eepromc_test to /usr/bin directory of the MYD-C437X-PRU development board, run eepromc_test application as below:
# chmod 777 /usr/bin/eeprom_test
# eeprom_test -h 
Usage: eeprom_test [options]

Version 1.0
Options:
-d | --device name   i2c device name: /dev/i2c-0
-a | --address addr     eeprom i2c address, default 0x50
-s | --start addr       start offset to read/write
-r | --read  count    read byte count
-w | --write frame      write frame string. such as: 0123456789
-h | --help                Print this message
  • Before testing write on EEPROM, write-protect should be disabled by outputing low level on GPIO3_7. During running of eeprom_test, it set write-protect to be disabled automatically, users do not need to handle manually. 
# echo 103 > /sys/class/gpio/export
# echo "out" > /sys/class/gpio/gpio103/direction
# echo 0 > /sys/class/gpio/gpio103/value
  • Read and write EEPROM as below: 
# eeprom_test -d /dev/i2c-0 -a 0x50 -w "hello world!"
WRITE:hello world!
WRITE SUCCESS!


# eeprom_test -d /dev/i2c-0 -a 0x50 -r 12
READ:hello world!
TOTAL 12 BYTES.