用IO模拟I2C

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/**************************************************************************//**

 * [url=home.php?mod=space&uid=288409]@file[/url]     main.c

 * [url=home.php?mod=space&uid=895143]@version[/url]  V1.00

 * [url=home.php?mod=space&uid=247401]@brief[/url]    Use GPIO to simuliate I2C waveform

 *

 * @note

 * Copyright (C) 2019 Nuvoton Technology Corp. All rights reserved.

 ******************************************************************************/

#include <stdio.h>

#include "NUC230_240.h"

#include "NuEdu-Basic01.h"





/*----------------------------------------------------------------------------*/

/* Define                                                                     */

/*----------------------------------------------------------------------------*/

#define I2C_ADDRESS_W   0xa0

#define I2C_ADDRESS_R   0xa1

#define I2C_DELAY_TIME  10

#define ACK             0

#define NO_ACK          1

#define I2C_CLK         PA11

#define I2C_DAT         PA10





/*----------------------------------------------------------------------------*/

/* Global variable                                                            */

/*----------------------------------------------------------------------------*/





/*----------------------------------------------------------------------------*/

/* Functions                                                                  */

/*----------------------------------------------------------------------------*/





void I2C_Init(void)

{

    /* Configure PA10 as open-drain mode */

    GPIO_SetMode(PA, BIT10, GPIO_PMD_OPEN_DRAIN);



    /* Configure PA11 as open-drain mode */

    GPIO_SetMode(PA, BIT11, GPIO_PMD_OPEN_DRAIN);



    /* Control PA11 output status */

    I2C_CLK = 1;



    /* Control PA10 output status */

    I2C_DAT = 1;

}





void I2C_Start(void)

{

    /*  I2C START Condition */

    I2C_DAT = 1;

    I2C_CLK = 1;



    /*  I2C delay 10us */

    CLK_SysTickDelay(I2C_DELAY_TIME);

    I2C_DAT = 0;

    I2C_CLK = 0;

    CLK_SysTickDelay(I2C_DELAY_TIME);

}





void I2C_Stop(void)

{

    /*  I2C STOP Condition */

    I2C_DAT = 0;

    I2C_CLK = 1;

    I2C_DAT = 1;

}





uint8_t I2C_Write(uint8_t u8Data)

{

    uint8_t u8Count;



    /* Write to slave */

    for (u8Count = 0; u8Count < 8; u8Count++)

    {

        /* Send data bit */

        if ((u8Data & 0x80) == 0x80)

            I2C_DAT = 1;

        else

            I2C_DAT = 0;



        /* Shift one bit */

        u8Data <<= 1;



        I2C_CLK = 1;



        /*  I2C delay 10us */

        CLK_SysTickDelay(I2C_DELAY_TIME);

        I2C_CLK = 0;

        CLK_SysTickDelay(I2C_DELAY_TIME);

    }



    I2C_DAT = 1;

    I2C_CLK = 1;



    /*  I2C delay 5us */

    CLK_SysTickDelay(I2C_DELAY_TIME / 2);



    /* Read ACK bit from slave */

    u8Data = I2C_DAT;



    CLK_SysTickDelay(I2C_DELAY_TIME / 2);

    I2C_CLK = 0;

    CLK_SysTickDelay(I2C_DELAY_TIME);

    return u8Data;

}





uint8_t I2C_Read(uint8_t u8Ack)

{

    uint8_t u8Data, u8Count;



    u8Data = 0x00;



    /* Read from slave */

    for (u8Count = 0; u8Count < 8; u8Count++)

    {

        /* Shift one bit */

        u8Data <<= 1;



        /* Read data bit */

        u8Data |= I2C_DAT;



        I2C_CLK = 1;

        CLK_SysTickDelay(I2C_DELAY_TIME);

        I2C_CLK = 0;

        CLK_SysTickDelay(I2C_DELAY_TIME);

    }



    /* Send ACK bit to slave */

    I2C_DAT = u8Ack;



    I2C_CLK = 1;



    /*  I2C delay 10us */

    CLK_SysTickDelay(I2C_DELAY_TIME);

    I2C_CLK = 0;

    CLK_SysTickDelay(I2C_DELAY_TIME);



    return u8Data;

}





void I2C_GPIO_Write_Byte(uint16_t u16Addr, uint8_t u8Data)

{

    uint8_t u8AddrH, u8AddrL;



    u8AddrH = u16Addr >> 8;

    u8AddrL = (uint8_t)u16Addr;



    /* Send Start bit to I2C EEPROM */

    I2C_Start();



    /* Send control byte to I2C EEPROM */

    printf("ack=0x%x,\n\r", I2C_Write(I2C_ADDRESS_W));



    /* Send I2C EEPROM's High Byte Address */

    printf("ack=0x%x,\n\r", I2C_Write(u8AddrH));



    /* Send I2C EEPROM's Low Byte Address */

    printf("ack=0x%x,\n\r", I2C_Write(u8AddrL));



    /* Send data byte to I2C EEPROM */

    printf("ack=0x%x,\n\r", I2C_Write(u8Data));



    /* Send Stop bit to I2C EEPROM */

    I2C_Stop();

}



void I2C_GPIO_Read_Byte(uint16_t u16Addr, uint8_t *pu8Data)

{

    uint8_t u8AddrH, u8AddrL;



    u8AddrH = u16Addr >> 8;

    u8AddrL = (uint8_t)u16Addr;



    /* Send Start bit to I2C EEPROM */

    I2C_Start();



    /* Send control byte to I2C EEPROM */

    printf("ack=0x%x,\n\r", I2C_Write(I2C_ADDRESS_W));



    /* Send I2C EEPROM's High Byte Address */

    printf("ack=0x%x,\n\r", I2C_Write(u8AddrH));



    /* Send I2C EEPROM's Low Byte Address */

    printf("ack=0x%x,\n\r", I2C_Write(u8AddrL));



    /* Send Start bit to I2C EEPROM */

    I2C_Start();



    /* Send control byte to I2C EEPROM */

    printf("ack=0x%x,\n\r", I2C_Write(I2C_ADDRESS_R));



    /* Read data byte from EEPROM */

    *pu8Data = I2C_Read(NO_ACK);



    /* Send Stop bit to I2C EEPROM */

    I2C_Stop();

}

/*----------------------------------------------------------------------------*/

/*  MAIN function                                                             */

/*----------------------------------------------------------------------------*/

int main(void)

{

    uint8_t u8Data;



    /* Init System */

    SYS_Init();



    /* Initial UART0 to 115200-8n1 for print message */

    UART0_Init();



    /* Init software I2C */

    I2C_Init();



    /* Write 0x55 into address 0x0000 */

    I2C_GPIO_Write_Byte(0x0000, 0x55);



    /* Delay 10ms */

    CLK_SysTickDelay(10000);



    /* Read 0x55 from address 0x0000 */

    I2C_GPIO_Read_Byte(0x0000, &u8Data);

    printf("data=0x%x,\n\r", u8Data);



    while (1);

}



/*** (C) COPYRIGHT 2019 Nuvoton Technology Corp. ***/

IO模拟I2C，要注意使用IO的开漏模式，这样，只有拉低和高阻态，高阻态的时候可以通过上拉电阻给总线拉高。这样就完美的模拟了I2C的物理特性。