> For the complete documentation index, see [llms.txt](https://dev.solid-run.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dev.solid-run.com/other-articles/snippets/tlv-writer-documentation.md). # TLV Writer Documentation *** ## **Table of Contents** * [Table of Contents](#table-of-contents) * [where to get](#where-to-get) * [Overview](#overview) * [Dependencies](#dependencies) * [Usage](#usage) * [Arguments](#arguments) * [Example Usage](#example-usage) * [Finding the I2C Bus Number](#finding-the-i2c-bus-number) * [Supported TLV Keys](#supported-tlv-keys) * [System Information (SMBIOS Type 1)](#system-information-smbios-type-1) * [NIO Information (SMBIOS Type 2)](#nio-information-smbios-type-2) * [Chassis Information (SMBIOS Type 3)](#chassis-information-smbios-type-3) * [Error Handling](#error-handling) * [Possible Errors](#possible-errors) *** ### where to get ### **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: * 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. *** ## Dependencies To ensure all required dependencies are installed, run: ``` 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. *** ## **Usage** ``` python3 TLV_write.py [--yes] [-b] ... ``` ### **Arguments** | **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`. | | | One or more key-value pairs to write to EEPROM. | ### **Example Usage** For example if we want the following data to appear in DMI: ``` Handle 0xXXXX, DMI type 1, XX bytes System Information Manufacturer: XXXXX Product Name: MySystem Version: 1.0 Serial Number: XXXXXX UUID: XXXXXX-XXXXX-XXXXX-XXXXX-XXXXX Wake-up Type: XXXXXXXXXXXX SKU Number: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Family: XXXXXXXXXXXXXXXXXXXXXXX ``` We want to run the following command (Note that bus 3 address 0X50 is used in this example): ``` python3 TLVwriter.py 3 0x50 TLV_CODE_SYS_NAME "MySystem" TLV_CODE_SYS_VERSION "1.0" ``` {% hint style="info" %} **eeprom example for this :** ``` 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 "01.02" \ TLV_CODE_FAMILY "Industrial" \ TLV_CODE_MANUF_NAME "Solid-Run" \ TLV_CODE_MANUF_DATE "2024-03-11" \ TLV_CODE_PLATFORM_NAME "Bedrock-IPC" ``` 00: 54 6c 76 49 6e 66 6f 00 01 65 00 30 0e 45 6d 62 TlvInfo.?e.0?Emb\ 10: 65 64 64 65 64 44 65 76 69 63 65 31 07 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 30 32 20 0a 49 6e 64 75 73 74 93?01.02 ?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 {% endhint %} {% hint style="info" %} **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., 3, 4, 5 etc.) until you detect an address 0x50 or 0x56. Once found, use the corresponding bus number in the script. **Example:** ``` sudo i2cdetect -y 3 ``` 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 3 and address 0x50 should be used in the script. {% endhint %} {% hint style="warning" %} Bus 2 or 5 usually has the memory SPD on addresses 0x50 & 0x51, **do not write to them!** {% endhint %} *** ## **Supported TLV Keys** Each TLV Key has a Hex Code, Max Length, and belongs to a DMIDecode Type. ### **System Information (SMBIOS Type 1)** | | | | | ------------------------------ | ---------------------- | ------------------------------------------------- | | **TLV Key** | **Max Length (bytes)** | **BIOS path** | | 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 | 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 | - | ### **NIO Information (SMBIOS 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 (SMBIOS Type 3)** | | | | ------------------------------ | ---------------------- | | **TLV Key** | **Max Length (bytes)** | | TLV\_CODE\_CHS\_SERIAL\_NUMBER | 24 | | TLV\_CODE\_CHS\_VERSION | 5 | | | | | | ----------------------- | ---------------------- | ---------------------------------------------------------------- | | **TLV Key** | **Max Length (bytes)** | **BIOS path** | | TLV\_CODE\_CONFIG\_CODE | 200 | Main → Detailed Configuration Information → Configuration String | *** ## **Error Handling** If invalid input is provided, the script will: * Print an **error message**. * **Exit** without modifying EEPROM contents. ### **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. | *** --- # Agent Instructions This documentation is published with GitBook. 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