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Table of Contents

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TLV_OVERVIEW_ANCH
TLV_OVERVIEW_ANCH
Overview

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

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  • Builds TLV-formatted payloads.

  • Writes the data into an EEPROM via I2C.

  • Supports custom-defined keys.

  • Calculates and appends a CRC checksum to ensure data integrity.

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TLV_usage_ANCH
TLV_usage_ANCH
Usage

Code Block
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

Code Block
python3 TLV_write.py 2 0x50 TLV_CODE_SYS_NAME "MySystem" TLV_CODE_SYS_VERSION "1.0"
Panel
panelIconId1f9d0
panelIcon:face_with_monocle:
panelIconText🧐
bgColor#B3D4FF

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

Info

Finding the I2C Bus Number

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

Code Block
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:

Code Block
sudo i2cdetect -y 2

If the output shows:

Code Block
     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.

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

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

This writes:

  • System Name: "MySystem"

  • System Version: "1.0" to EEPROM at I2C bus 2, address 0x50.

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TLV_KEYS_ANCH
TLV_KEYS_ANCH
Supported TLV Keys

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

System Information (SMBUS Type 1)

TLV KeyHex Code

Max Length (bytes)

TLV_CODE_FAMILY0x20

20

TLV_CODE_MANUF_DATE

0x23

10

TLV_CODE_PLATFORM_NAME

0x24

20

TLV_CODE_MANUF_NAME0x25

20

TLV_CODE_VENDOR_NAME0x27

20

TLV_CODE_SYS_NAME0x30

20

TLV_CODE_SYS_SKU0x31

20

TLV_CODE_SYS_SERIAL_NUMBER

0x32

24

TLV_CODE_SYS_VERSION

0x33

5

NIO Information (

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SMBUS Type: 2)

TLV KeyHex Code

Max Length (bytes)

TLV_CODE_NIO_NAME0x40

20

TLV_CODE_NIO_SERIAL_NUMBER0x41

24

TLV_CODE_NIO_VERSION

0x42

5

Chassis Information (

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SMBUS Type: 3)

TLV Key

Hex Code

Max Length (bytes)

TLV_CODE_CHS_SERIAL_NUMBER0x50

24

TLV_CODE_CHS_VERSION0x51

5

TLV_CODE_CONFIG_CODE

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:

This entry will only be displayed in BIOS main menu.

Main → Detailed Configuration Information → Configuration String

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TLV_ERROR_HANDLING_ANCH
TLV_ERROR_HANDLING_ANCH
Error Handling

If invalid input is provided, the script will:

  • Print an error message.

  • Exit without modifying EEPROM contents.

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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.

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TLV_DEPENDENCIES_ANCH
TLV_DEPENDENCIES_ANCH
Dependencies

This script requires:

  • Python 3

  • smbus (I2C communication)

  • struct and binascii (binary manipulation)

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