I2C Integration Guide

Overview

The CFBD I2C abstraction provides a platform-independent interface for I2C communication. Backend implementations (e.g., STM32) provide concrete device drivers, while the abstraction layer ensures consistent behavior across different hardware platforms.

Architecture

The I2C system consists of:

• Operations Table ([CFBD_I2COperations](Classes/structCFBD__I2COperations.md)): Backend implementation hooks
• I2C Handle ([CFBD_I2CHandle](Classes/structCFBD__I2CHandle.md)): Public interface + private backend state
• Messages ([CFBD_I2C_Message](Classes/structCFBD__I2C__Message.md)): Protocol-level read/write operations
• High-Level Helpers (CFBD_I2CRead, CFBD_I2CWrite): Convenience functions

Typical Usage Workflow

Initialization

// 1. Create I2C handle (typically done by backend platform code)
CFBD_I2CHandle i2c_bus = {
    .ops = &i2c_stm_operations,      // Backend operations table
    .private_handle = &i2c_hardware  // Platform-specific state
};

// 2. Initialize the I2C bus
int status = CFBD_I2CInit(&i2c_bus);
if (status != I2C_OK) {
    // Handle initialization error
}

Message Transfer

// Example: Read from OLED at address 0x3C
CFBD_I2C_Message msgs[2];
uint8_t reg_addr = 0x00;  // Register to read
uint8_t data_buffer[32];  // Read buffer

// Message 1: Write register address
msgs[0].addr = 0x3C;
msgs[0].flags = 0;
msgs[0].len = 1;
msgs[0].buf = &reg_addr;

// Message 2: Read data (uses I2C_M_RD flag)
msgs[1].addr = 0x3C;
msgs[1].flags = I2C_M_RD;
msgs[1].len = sizeof(data_buffer);
msgs[1].buf = data_buffer;

// Execute combined write-read transaction
status = CFBD_I2CTransfer(&i2c_bus, msgs, 2, 1000);
if (status == I2C_OK) {
    // data_buffer now contains read data
}

Using Convenience Helpers

CFBD_I2C_IORequestParams req = {
    .addr7 = 0x3C,
    .mem_addr = 0x10,        // Device internal address
    .mem_addr_size = 1,      // 1 byte address
    .data = buffer,
    .len = sizeof(buffer),
    .timeout_ms = 1000
};

// Simple high-level read
status = CFBD_I2CRead(&i2c_bus, &req);

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Updated on 2026-02-03 at 13:21:55 +0000