Table of Contents

Overview

This script writes TLV (Type-Length-Value) structured data into an I2C EEPROM. It supports a variety of system-specific keys that define metadata for the device.

The script:

Usage

python3 TLV_write.py <i2c_bus> <eeprom_address> [--yes] <key> <value> <key> <value> ...

Arguments

Argument

Description

i2c_bus

The I2C bus number.

eeprom_address

The EEPROM address (hex or decimal).

--yes (optional)
-y
--force

Automatically confirms the operation (skips user confirmation).

<key> <value>

One or more key-value pairs to write to EEPROM.

Example Usage

python3 TLV_write.py 2 0x50 TLV_CODE_SYS_NAME "MySystem" TLV_CODE_SYS_VERSION "1.0"

as you can see this usage write that the System name is “MySystem“ , the i2c_bus is 2 and eeprom_address is 0X50.

Finding the I2C Bus Number

To determine the correct I2C bus number, run the following command:

sudo i2cdetect -y 1

If no EEPROM device is found, repeat the command with different bus numbers (e.g., 2, 3, 4, etc.) until you detect an address 0x50 or 0x56. Once found, use the corresponding bus number in the script.

Example:

sudo i2cdetect -y 2

If the output shows:

     0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

Then bus 2 and address 0x50 should be used in the script.

Supported TLV Keys

Each TLV Key has a Hex Code, Max Length, and belongs to a DMIDecode Type.

System Information (SMBUS Type 1)

TLV Key

Max Length (bytes)

TLV_CODE_FAMILY

20

TLV_CODE_MANUF_DATE

10

TLV_CODE_PLATFORM_NAME

20

TLV_CODE_MANUF_NAME

20

TLV_CODE_VENDOR_NAME

20

TLV_CODE_SYS_NAME

20

TLV_CODE_SYS_SKU

20

TLV_CODE_SYS_SERIAL_NUMBER

24

TLV_CODE_SYS_VERSION

5

NIO Information (SMBUS Type: 2)

TLV Key

Max Length (bytes)

TLV_CODE_NIO_NAME

20

TLV_CODE_NIO_SERIAL_NUMBER

24

TLV_CODE_NIO_VERSION

5

Chassis Information (SMBUS Type: 3)

TLV Key

Max Length (bytes)

TLV_CODE_CHS_SERIAL_NUMBER

24

TLV_CODE_CHS_VERSION

5

TLV_CODE_CONFIG_CODE:

This entry will only be displayed in BIOS main menu.

Main → Detailed Configuration Information → Configuration String

Error Handling

If invalid input is provided, the script will:

Possible Errors

Error Message

Cause

Error: Unknown key

Provided TLV key is not in the supported list.

Error: Value for key 'X' is too long

Input exceeds the maximum allowed length.

Error: MAC address must have 6 parts

Incorrect MAC format.

Error: I2C write error

I2C communication issue during EEPROM write.

Error: Total TLV data length exceeds EEPROM capacity

Data is too large for EEPROM storage.

Dependencies

This script requires:

To install missing dependencies:

sudo apt install python3-smbus