1、Reading EEPROM
hexdump -C /sys/bus/i2c/devices/3-0057/eeprom
2、Write content to EEPROM
printf '\x01\x02\x03\x04\x05\x06' | dd of=/sys/bus/i2c/devices/3-0057/eeprom bs=1 seek=32 conv=notrunc
“\x01\x02\x03\x04\x05\x06” is the content you want to write, which can be a MAC address, serial number, or other information.
“bs=1” means the block size is 1.
“seek=32” means the offset (how many blocks to skip).
"bs=1 seek=32" means to skip 32 bytes, which corresponds to skipping bytes from 0x00 to 0x1F, and start writing content from 0x20.
“conv=notrunc” do not truncate the EEPROM, preserve the original data.
For example, I want to write two sets of MAC addresses to addresses 0x20 and 0x30 respectively:
printf '\x12\x41\x89\x7F\x64\xD3' | dd of=/sys/bus/i2c/devices/3-0057/eeprom bs=1 seek=32 conv=notrunc
printf '\x7E\xF5\x56\x36\x4C\xD1' | dd of=/sys/bus/i2c/devices/3-0057/eeprom bs=1 seek=48 conv=notrunc
PS: Since subsequent batches of the V1.2 version are planned to write data to the EEPROM, addresses ranging from 0x00 to 0x1F must be avoided.
3、Read all contents of the EEPROM.
hexdump -C /sys/bus/i2c/devices/3-0057/eeprom
Read the content at a specified location in the EEPROM.
hexdump -C /sys/bus/i2c/devices/3-0057/eeprom | tail -n +3
“tail -n +3” indicates that only the data starting from the third line should be displayed, which is 0x20.
The image file officially released by BananaPi uses a random MAC address every time it is started and does not use EEPROM. If you want to use EEPROM, you will also need to write an additional script to read the data and update the port.