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PMBus Command Interface Documentation

Table of Contents

  1. Introduction
  2. Command Structure
  3. System Commands
  4. Configuration Commands
  5. Error Handling
  6. PMBus Commands Documentation
  7. System Diagram

Introduction

This document provides detailed information on the PMBus Command Interface, including PMBus commands, system commands, and configuration commands. The interface is designed for STM32G4 microcontrollers using FreeRTOS.

Command Structure

All commands follow this general structure:

[TYPE] [CMD] [DATA] \n

  • [TYPE]: Single digit representing the command type
    • 0: PMBus command
    • 1: System command
    • 2: Configuration command
  • [CMD]: Three-digit command code
  • [DATA]: Optional data (format depends on the command)
  • \n: Newline character (required to end the command)

System Commands

System commands control overall system behavior.

Format: [1][CMD][DATA][\n]

Available System Commands

Command Code Description
SYS_GET_OS_VERSION 000 Get the OS version
SYS_SCAN_ACTIVE_ADDR 001 Scan for active PMBus addresses
SYS_UPDATE_FIRMWARE 002 Initiate firmware update
SYS_RESET 003 Perform system reset
SYS_GET_UPTIME 004 Get system uptime
SYS_GET_MEMORY_STATS 005 Get memory usage statistics
SYS_GET_CPU_USAGE 006 Get CPU usage information
SYS_GET_HARDWARE_INFO 007 Get hardware information

Example usage:

  • Get OS Version: 1000\n
  • Scan for active PMBus addresses: 1001\n

Configuration Commands

  • CONF_SET_ADDRESS (000): Set PMBus address
  • CONF_GET_ADDRESS (001): Get current PMBus address
  • CONF_VERBOSE_LOGGING (002): Set log verbosity
  • CONF_SET_UART_BAUD (003): Set UART baud rate
  • CONF_GET_UART_BAUD (004): Get current UART baud rate
  • CONF_SET_PMBUS_FREQUENCY (005): Set PMBus frequency
  • CONF_GET_PMBUS_FREQUENCY (006): Get current PMBus frequency
  • CONF_ENABLE_LOGGING (007): Enable logging
  • CONF_DISABLE_LOGGING (008): Disable logging
  • CONF_RESET_TO_DEFAULT (009): Reset to default settings

Log Verbosity Levels

  • MUTE (0): Only critical and error messages
  • NORMAL (1): Critical, error, and warning messages
  • LOUD (2): All messages except debug
  • VERBOSE (3): All messages including debug

Usage

Send commands via UART in the following format: <command_type> <command_code> <data> <\n>

Where:

  • <command_type> is 0 for PMBus, 1 for System, 2 for Config
  • <command_code> is a three-digit number
  • <data> is optional and command-specific
  • \n is the newline character

Example: 20021\n

This sets the log verbosity to NORMAL.

Configuration Commands

Configuration commands modify the behavior of the PMBus interface itself.

Format: [2][CMD][DATA][\n]

Available Configuration Commands

Command Code Description Data Format
CONF_SET_ADDRESS 000 Set PMBus address 2 bytes (hex)
CONF_GET_ADDRESS 001 Get current PMBus address None
CONF_VERBOSE_LOGGING 002 Set log verbosity 1 byte (0-3)
CONF_SET_UART_BAUD 003 Set UART baud rate 1 byte (enum)
CONF_GET_UART_BAUD 004 Get current UART baud rate None
CONF_SET_PMBUS_FREQUENCY 005 Set PMBus clock frequency 1 byte (enum)
CONF_GET_PMBUS_FREQUENCY 006 Get current PMBus clock frequency None
CONF_RESET_TO_DEFAULT 007 Reset all configurations to default None

CONF_VERBOSE_LOGGING Data Values

  • 0: MUTE (critical errors only)
  • 1: NORMAL (errors and warnings)
  • 2: LOUD (errors, warnings, and info)
  • 3: VERBOSE (all messages including debug)

CONF_SET_UART_BAUD Data Values

  • 0: 9600 baud
  • 1: 19200 baud
  • 2: 38400 baud
  • 3: 57600 baud
  • 4: 115200 baud
  • 5: 230400 baud
  • 6: 460800 baud
  • 7: 921600 baud

CONF_SET_PMBUS_FREQUENCY Data Values

  • 0: 100 kHz (Standard mode)
  • 1: 400 kHz (Fast mode)
  • 2: 1 MHz (Fast mode plus)

Example usage:

  • Set PMBus address to 0xB2: 2000178\n
  • Set log verbosity to NORMAL: 20021\n
  • Set UART baud rate to 115200: 20034\n

Error Handling

If a command is invalid or cannot be executed, an error message will be logged. The system will attempt to continue operation. Check the system logs for detailed error information.

Common errors include:

  • Invalid command format
  • Unknown command
  • Invalid data for a command
  • PMBus communication errors
  • System resource limitations

For critical errors, the system may initiate a recovery procedure or reset.

PMBus Commands Documentation

Table of Contents

  1. Introduction
  2. Command Format
  3. PMBus Commands

Introduction

This document provides a comprehensive list of PMBus commands implemented in this system. Each command is listed with its name and corresponding decimal command code.

Command Format

PMBus commands are sent in the following format:

Format: [0][CMD][R/W][DATA][\n]

  • [0]: Indicates a PMBus command
  • [CMD]: Three-digit decimal command code
  • [R/W]: 0 for read, 1 for write
  • [DATA]: Decimal data for write operations (omitted for read operations)
  • [\n]: Newline character to end the command

Example:

  • To read VOUT_COMMAND (command code 33): 00330\n
  • To write VOUT_COMMAND: 003311000\n

PMBus Commands

Basic Operation Commands

Command Code Description
PAGE 000 Set/Get the current page
OPERATION 001 Set/Get the operation state
ON_OFF_CONFIG 002 Set/Get the on/off configuration
CLEAR_FAULT 003 Clear all faults
PHASE 004 Set/Get the current phase
WRITE_PROTECT 010 Set/Get write protection status
STORE_DEFAULT_ALL 011 Store current settings as defaults
RESTORE_DEFAULT_ALL 012 Restore default settings
CAPABILITY 019 Get device capabilities
SMBALERT_MASK 027 Set/Get the SMBAlert mask

Output Voltage Commands

Command Code Description
VOUT_MODE 032 Get the supported output voltage format and exponent
VOUT_COMMAND 033 Set/Get the output voltage
VOUT_MAX 036 Set/Get the maximum output voltage
VOUT_MARGIN_HIGH 037 Set/Get the high margin output voltage
VOUT_MARGIN_LOW 038 Set/Get the low margin output voltage
VOUT_TRANSITION_RATE 039 Set/Get the output voltage transition rate
VOUT_DROOP 040 Set/Get the output voltage droop
VOUT_SCALE_LOOP 041 Set/Get the output voltage scale loop
VOUT_SCALE_MONITOR 042 Set/Get the output voltage scale monitor
VOUT_MIN 043 Set/Get the minimum output voltage

Input Commands

Command Code Description
FREQUENCY_SWITCH 051 Set/Get the switching frequency
VIN_ON 053 Set/Get the input voltage turn-on threshold
IOUT_CAL_GAIN 056 Set/Get the output current calibration gain
IOUT_CAL_OFFSET 057 Set/Get the output current calibration offset

Fault Commands

Command Code Description
VOUT_OV_FAULT_LIMIT 064 Set/Get the output overvoltage fault limit
VOUT_OV_FAULT_RESPONSE 065 Set/Get the output overvoltage fault response
VOUT_UV_FAULT_LIMIT 068 Set/Get the output undervoltage fault limit
VOUT_UV_FAULT_RESPONSE 069 Set/Get the output undervoltage fault response
IOUT_OC_FAULT_LIMIT 070 Set/Get the output overcurrent fault limit
IOUT_OC_FAULT_RESPONSE 071 Set/Get the output overcurrent fault response
IOUT_OC_WARN_LIMIT 074 Set/Get the output overcurrent warning limit
VIN_OV_FAULT_LIMIT 085 Set/Get the input overvoltage fault limit
VIN_OV_FAULT_RESPONSE 086 Set/Get the input overvoltage fault response
VIN_UV_FAULT_LIMIT 089 Set/Get the input undervoltage fault limit
VIN_UV_FAULT_RESPONSE 090 Set/Get the input undervoltage fault response
IIN_OC_FAULT_LIMIT 091 Set/Get the input overcurrent fault limit
IIN_OC_FAULT_RESPONSE 092 Set/Get the input overcurrent fault response
IIN_OC_WARN_LIMIT 093 Set/Get the input overcurrent warning limit

Temperature Commands

Command Code Description
OT_FAULT_LIMIT 079 Set/Get the overtemperature fault limit
OT_FAULT_RESPONSE 080 Set/Get the overtemperature fault response
OT_WARN_LIMIT 081 Set/Get the overtemperature warning limit

Status Commands

Command Code Description
STATUS_BYTE 120 Read the status byte
STATUS_WORD 121 Read the status word
STATUS_VOUT 122 Read the output voltage status
STATUS_IOUT 123 Read the output current status
STATUS_INPUT 124 Read the input status
STATUS_TEMPERATURE 125 Read the temperature status
STATUS_CML 126 Read the communication, memory and logic status
STATUS_MFR_SPECIFIC 128 Read manufacturer specific status information

Reading Commands

Command Code Description
READ_VIN 136 Read the input voltage
READ_IIN 137 Read the input current
READ_VOUT 139 Read the output voltage
READ_IOUT 140 Read the output current
READ_TEMPERATURE_1 141 Read temperature 1
READ_POUT 148 Read the output power
READ_PIN 149 Read the input power

Manufacturer Specific Commands

Command Code Description
PMBUS_REVISION 152 Read the supported PMBus version
MFR_ID 153 Read the manufacturer ID
MFR_MODEL 154 Read the manufacturer model
MFR_REVISION 155 Read the manufacturer revision
MFR_DATE 156 Read the manufacture date
MFR_SERIAL 157 Read the manufacturer serial number
IC_DEVICE_ID 173 Read the IC device ID
IC_DEVICE_REV 174 Read the IC device revision
MFR_SPECIFIC_00 208 Manufacturer specific command 00
MFR_SPECIFIC_03 to MFR_SPECIFIC_15 211-223 Manufacturer specific commands 03 to 15
MFR_SPECIFIC_20 228 Manufacturer specific command 20
MFR_SPECIFIC_32 240 Manufacturer specific command 32
MFR_SPECIFIC_42 250 Manufacturer specific command 42

User Data Commands

Command Code Description
USER_DATA_00 to USER_DATA_12 176-188 Read/Write user data 00 to 12

Note: This list includes all the PMBus commands implemented in this system. Some commands may have specific data formats or restrictions. Always refer to the PMBus specification and your device's datasheet for detailed information on how to use each command.

System Diagram

graph TD
    A[Start System] --> B[Initialize Hardware]
    B --> C[Initialize RTOS]
    C --> D[Start Tasks]
    D --> E[UART Task]
    D ---> F[PMBus Task]
    D ---> G[Command Processing Task]
    D ---> H[Log Task]
    D --> I[Supervisor Task]

    E --> J[Receive Command]
    J --> K{Parse Command}
    K -->|PMBus| L[Queue PMBus Command]
    K -->|System| M[Queue System Command]
    K -->|Config| N[Queue Config Command]
    K -->|Invalid| O[Log Error]

    L --> P[Command Processing Task]
    M --> P
    N --> P

    P --> Q{Command Type}
    Q --->|PMBus| R[Acquire PMBus Mutex]
    Q -->|System| S[Execute System Command]
    Q -->|Config| T[Execute Config Command]

    subgraph PMBus Communication
        R ---> U{Read/Write}
        U -->|Read| V[Read from PMBus Device]
        U -->|Write| W[Write to PMBus Device]
        V --> X[Format PMBus Response]
        W --> X
        X --> Y[Calculate PEC]
    end

    Y --> Z[Release PMBus Mutex]
    Z --> AO[Log Task]
    S --> AO
    T --> AO
    AO--> AA[Log Result]
    AA --> AB[Send Response]

    I ---> AC[Monitor System Health]
    I ---> AD[Manage Recovery]

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About

UART-PMBUS Interface About This project implements a Real-Time Operating System (RTOS) based UART to PMBUS interface for programming VRM PWM controllers. Designed for the STM32G474RE microcontroller on the NUCLEO-G474RE board, it leverages CMSIS-RTOS2 for task management and implements robust error recovery mechanisms.

Topics

c i2c stm32 cmsis rtos embedded-c pmbus

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