I2C MASTER Example

Source code path: example/hal/i2c/master

Supported Platforms

The example can run on the following development boards:

sf32lb52-lcd_n16r8
sf32lb58-lcd_n16r64n4
sf32lb56-lcd_n16r12n1

Overview

This example demonstrates how to use the chip’s I2C interface to implement master-slave communication functionality. The code implements I2C Master Mode (EXAMPLE_I2C_MASTER), in this mode:

Initialize I2C interface in master mode
Actively send 4-byte data {0x11, 0x22, 0x33, 0x44} to the slave at address 0x5A
Read 4-byte response data from the same slave

Working Principle

In master mode, the device cyclically performs the following operations:

Send preset 4-byte test data to the slave
Delay 100 milliseconds
Read 4-byte response data from the slave
Repeat the above process after 2 seconds

Example Usage

Using sf32lb52-lcd_n16r8 development board as an example, run this example and check the serial output.

Hardware Requirements

Before running this example, you need to prepare:

One development board supported by this example
Several Dupont wires

Hardware Connection

The I2C connection method for two development boards is as follows:

Development Board	SDA Pin	SDA Pin Name	SCL Pin	SCL Pin Name
sf32lb52-lcd_n16r8	3	PA42	5	PA41
sf32lb56-lcd_n16r12n1	3	PA12	5	PA20
sf32lb58-lcd_n16r64n4	3 (CONN1)	PB29	5 (CONN1)	PB28

Compilation and Programming

Switch to the example project directory and run the scons command to compile:

scons --board=sf32lb52-lcd_n16r8 -j8

Run build_sf32lb52-lcd_n16r8_hcpu\uart_download.bat, and follow the prompts to select the port for downloading:

build_sf32lb52-lcd_n16r8_hcpu\uart_download.bat

Uart Download

please input the serial port num:5

Example Output Results:

Log output:

SFBL
11-18 20:11:23:800    Serial:c2,Chip:4,Package:3,Rev:2  Reason:00000000
11-18 20:11:23:806     \ | /
11-18 20:11:23:807    - SiFli Corporation
11-18 20:11:23:808     / | \     build on Nov 18 2025, 2.4.0 build dd4cae55
11-18 20:11:23:809     2020 - 2022 Copyright by SiFli team
11-18 20:11:23:811    mount /dev sucess
11-18 20:11:23:812    [I/drv.rtc] PSCLR=0x80000100 DivAI=128 DivAF=0 B=256
11-18 20:11:23:813    [I/drv.rtc] RTC use LXT RTC_CR=00000001
11-18 20:11:23:814    [I/drv.rtc] Init RTC, wake = 0
11-18 20:11:23:817    [I/drv.audprc] init 00 ADC_PATH_CFG0 0x606
11-18 20:11:23:818    [I/drv.audprc] HAL_AUDPRC_Init res 0
11-18 20:11:23:819    [I/drv.audcodec] HAL_AUDCODEC_Init res 0
11-18 20:11:23:820    [32m[I/TOUCH] Regist touch screen driver, probe=1203bd11 [0m
11-18 20:11:23:823    call par CFG1(3313)
11-18 20:11:23:825    fc 9, xtal 2000, pll 2040
11-18 20:11:23:826    call par CFG1(3313)
11-18 20:11:23:827    fc 9, xtal 2000, pll 2040
11-18 20:11:23:828    Start I2C Slave Demo!
11-18 20:11:23:830    I2C Master Init Success!
11-18 20:11:23:834    === I2C Communication Test Start ===
11-18 20:11:23:835    Master sending 4 bytes to slave 0x5A: 0x11 0x22 0x33 0x44 
11-18 20:11:23:837    Master transmit success!
11-18 20:11:23:838    Master reading 4 bytes from slave 0x5A
11-18 20:11:23:840    Master receive success, data: 0xAA 0xBB 0xCC 0xDD
11-18 20:11:23:842    === I2C Communication Test End ===
11-18 20:11:23:849    msh />
11-18 20:11:24:315    === I2C Communication Test Start ===
11-18 20:11:24:317    Master sending 4 bytes to slave 0x5A: 0x11 0x22 0x33 0x44 
11-18 20:11:24:342    Master transmit success!
11-18 20:11:24:443    Master reading 4 bytes from slave 0x5A
11-18 20:11:24:445    Master receive success, data: 0xAA 0xBB 0xCC 0xDD 
11-18 20:11:24:446    === I2C Communication Test End ===
11-18 20:11:24:944    === I2C Communication Test Start ===
11-18 20:11:24:944    Master sending 4 bytes to slave 0x5A: 0x11 0x22 0x33 0x44 
11-18 20:11:24:947    Master transmit success!
11-18 20:11:25:042    Master reading 4 bytes from slave 0x5A
11-18 20:11:25:045    Master receive success, data: 0xAA 0xBB 0xCC 0xDD 
11-18 20:11:25:046    === I2C Communication Test End ===
11-18 20:11:25:543    === I2C Communication Test Start ===
11-18 20:11:25:546    Master sending 4 bytes to slave 0x5A: 0x11 0x22 0x33 0x44 
11-18 20:11:25:547    Master transmit success!
11-18 20:11:25:644    Master reading 4 bytes from slave 0x5A
11-18 20:11:25:646    Master receive success, data: 0xAA 0xBB 0xCC 0xDD 
11-18 20:11:25:647    === I2C Communication Test End ===

I2C Read/Write Waveforms

Waveforms captured by logic analyzer

I2C master read waveform
I2C master write waveform

I2C Parameter Modification

static I2C_HandleTypeDef hi2c;

#define SLAVE_ADDRESS 0x5A //slave address
uint8_t master_tx_data[] = {0x11, 0x22, 0x33, 0x44};//master send data
uint8_t master_rx_data[4];//master receive data

void I2C_Master_Init(void)
{
    HAL_StatusTypeDef ret;
    
    //pin nux
#ifdef SF32LB52X
    HAL_RCC_EnableModule(RCC_MOD_I2C2); // enable i2c2
    HAL_PIN_Set(PAD_PA41, I2C2_SCL, PIN_PULLUP, 1); // i2c io select
    HAL_PIN_Set(PAD_PA42, I2C2_SDA, PIN_PULLUP, 1);
#define SLAVE_I2C I2C2// i2c number of cpu
#elif defined(SF32LB58X)
    HAL_RCC_EnableModule(RCC_MOD_I2C6);  // enable i2c6
    HAL_PIN_Set(PAD_PB28, I2C6_SCL, PIN_PULLUP, 0); // i2c io select
    HAL_PIN_Set(PAD_PB29, I2C6_SDA, PIN_PULLUP, 0);
#define SLAVE_I2C I2C6// i2c number of cpu
#elif defined(SF32LB56X)
    HAL_RCC_EnableModule(RCC_MOD_I2C3); // enable i2c3
    HAL_PIN_Set(PAD_PA20, I2C3_SCL, PIN_PULLUP, 1); // i2c io select
    HAL_PIN_Set(PAD_PA12, I2C3_SDA, PIN_PULLUP, 1);
#define SLAVE_I2C I2C3// i2c number of cpu
#endif
    //i2c init
    hi2c.Instance = MASTER_I2C;
    hi2c.Mode = HAL_I2C_MODE_MASTER; // i2c master mode
    hi2c.Init.ClockSpeed = 400000;           // 400kHz
    hi2c.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
    hi2c.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;

    ret = HAL_I2C_Init(&hi2c);
    if (ret != HAL_OK) {
        rt_kprintf("I2C Master Init failed: %d\n", ret);
        return;
    }
    rt_kprintf("I2C Master Init Success!\n");
}

Based on chip type to distinguish development boards, in the initialization function, for specific chips, configure the corresponding I2C pins
For example, through #elif defined(SF32LB52X)
chip to determine which development board is being used
Through #define EXAMPLE_I2C I2C2
the I2C controller number used by the chip (such as I2C6, I2C3)
Through #define EXAMPLE_I2C_IRQ I2C6_IRQn
the interrupt number corresponding to this I2C controller (for interrupt mode)
Finally, use the HAL_PIN_Set() function to configure the I2C SCL and SDA pins, which need to be set to pull-up mode

Note:

Except for 55x chips, PA*_I2C_UART functional IO can be configured to output I2C SDA, SCLK waveforms
The last parameter of HAL_PIN_Set is hcpu/lcpu selection, 1: select hcpu, 0: select lcpu

Troubleshooting

No I2C waveform output

Check against the chip manual whether the CPU’s I2C selection is correct
Check whether the IO configuration and connection are correct