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Table of Contents

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Overview

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Usage

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Supported Keys

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Error Handling

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Table of Contents
minLevel1
maxLevel6
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where to get

https://github.com/SolidRun/PyTLVWriter

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TLV_OVERVIEW_ANCH
TLV_OVERVIEW_ANCH
Overview

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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_DEPENDENCIES_ANCH
TLV_DEPENDENCIES_ANCH
Dependencies

To ensure all required dependencies are installed, run:

Code Block
sudo apt update
sudo apt install python3 python3-smbus

this will:

  • Install Python 3 if it is not already installed.

  • Install smbus for I2C communication.

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TLV_USAGE_ANCH
TLV_USAGE_ANCH
Usage

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

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Argument

Description

i2c_bus

The I2C bus number.

eeprom_address

The EEPROM address (hex or decimal).

--yes
-y
--force

Automatically confirms the operation (skips user confirmation).

-b

Writes the TLV data to a binary file (/tmp/eeprom_tlv.bin) without writing to the EEPROM. You can later write it manually using dd.

<key> <value>

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

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We want to run the following command (Note that bus 3 address 0X50 is used in this example):

Code Block
python3 TLV_writeTLVwriter.py 3 0x50 TLV_CODE_SYS_NAME "MySystem" TLV_CODE_SYS_VERSION "1.0"
Panel
bgColor#FFFFFF

eeprom example for this :

Code Block
python3 TLVwriter.py 3 0x50 TLV_CODE_SYS_NAME "EmbeddedDevice" \
      TLV_CODE_SYS_SKU "ED-2024" \
      TLV_CODE_SYS_SERIAL_NUMBER "SN123456789" \
      TLV_CODE_SYS_VERSION "101.2.302" \
      TLV_CODE_FAMILY "Industrial" \
      TLV_CODE_MANUF_NAME "TechCorpSolid-Run" \
      TLV_CODE_MANUF_DATE "2024-03-11" \
      TLV_CODE_PLATFORM_NAME "ARM CortexBedrock-A72IPC"

00: 54 6c 76 49 6e 66 6f 00 01 65 0030 0e 45 6d 62 TlvInfo.?e.0?Emb
10: 65 64 64 65 64 44 65 76 69 63 65 3107 45 44 2d eddedDevice1?ED-
20: 32 30 32 34 32 0b 53 4e 31 32 33 34 35 36 37 38 20242?SN12345678
30: 39 33 05 30 31 2e 2E 30 32 2e 33 20 0a 49 6e 64 75 73 74 93?101.2.302?Indust
40: 72 69 61 6c 25 09 73 6f 6c 69 64 2d 72 75 6e 23 rial%.solid-run#
50: 0a 32 30 32 34 2d 30 33 2d 31 31 24 0b 42 65 64 .2024-03-11$.Bed
60: 72 6f 63 6b 2d 49 50 43 fe 04 6e 7e c0 fd 00 00 rock-IPC??n~??
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
80: ……

header

version

Total Payload Length (little endian)

Type

Length

Value

crc checksum TLV

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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, 5 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 23

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 3 and address 0x50 should be used in the script.

Note

Bus 2 or 5 usually has the memory SPD on addresses 0x50 & 0x51, do not write to them!

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Supported TLV Keys

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

System Information (

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SMBIOS Type 1)

TLV Key

Max Length (bytes)

BIOS path

TLV_CODE_FAMILY

20

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TLV_CODE_MANUF_DATE

10

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TLV_CODE_PLATFORM_NAME

20

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TLV_CODE_MANUF_NAME

20

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TLV_CODE_VENDOR_NAME

20

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TLV_CODE_SYS_NAME

20-

Main → Detailed Configuration Information → Model

TLV_CODE_SYS_SKU

20

Main screen

TLV_CODE_SYS_SERIAL_NUMBER

24

Main screen

TLV_CODE_SYS_VERSION

5

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NIO Information (

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SMBIOS Type

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2)

TLV Key

Max Length (bytes)

TLV_CODE_NIO_NAME

20

TLV_CODE_NIO_SERIAL_NUMBER

24

TLV_CODE_NIO_VERSION

5

Chassis Information (

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SMBIOS Type

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3)

TLV Key

Max Length (bytes)

TLV_CODE_CHS_SERIAL_NUMBER

24

TLV_CODE_CHS_VERSION

5

This entry will only be displayed in BIOS main menu.

TLV Key

Max Length (bytes)

BIOS path

TLV_CODE_CONFIG_CODE

200

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Main → Detailed Configuration Information → Configuration String

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TLV_ERROR_HANDLING_ANCH
TLV_ERROR_HANDLING_ANCH
Error Handling

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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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Code Block
sudo apt update
sudo apt install python3 python3-smbus

this will:

  • Install Python 3 if it is not already installed.

  • Install smbus for I2C communication.

The script also requires the following Python modules, which are typically built-in:

  • sys

  • struct

  • binascii

  • time

To verify that all required Python modules are available, run:

Code Block
python3 -c "import struct, binascii, sys, time; print('All built-in modules are available')"

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.

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