gd32450i-eval/app/bmc/AuthChip/CM_I2C.c

// Functions that directly control the hardware

#include "CM_LIB.h"
#include "CM_I2C.h"
#include "CM_I2C_L.h"
#include "hal_interface_api.h"
#include <unistd.h>

// Delay
void cm_Delay(uint8_t ucDelay)
{
	uint32_t ucTimer;
	uint8_t a,b = 0;  
    while(ucDelay) {
    	ucTimer = 2000;
        while(ucTimer) 
        {
            ucTimer--;
            a = b;
        }
    	ucDelay--;
    }	
}

// 1/2 Clock Cycle transition to HIGH
//
void cm_Clockhigh(void)
{
    cm_Delay(1);
    CM_CLK_HI;
    cm_Delay(1);
}

// 1/2 Clock Cycle transition to LOW
//
void cm_Clocklow(void)
{
    cm_Delay(1);
    CM_CLK_LO;
    cm_Delay(1);
}

// Do one full clock cycle
//
// Changed 1/19/05 to eliminate one level of return stack requirements
//
void cm_ClockCycle(void)
{
    cm_Clocklow();
    cm_Clockhigh();
}

// Do a number of clock cycles
//
void cm_ClockCycles(uint8_t ucCount)
{
    uint8_t i;
    
    for (i = 0; i < ucCount; ++i) cm_ClockCycle();
}

// Send a start sequence
//
// Modified 7-21-04 to correctly set SDA to be an output
// 
void cm_Start(void)
{
	cm_Delay(50);//by jgw for delay to avoid i2c dead because of too fast
	  CM_DATA_OUT;                         // Data line must be an output to send a start sequence
	  //cm_Clocklow();
	  CM_DATA_HI;
	  cm_Delay(4);
	  cm_Clockhigh();
	  cm_Delay(4);
	  CM_DATA_LO;
	  cm_Delay(8);
	  cm_Clocklow();
	  cm_Delay(8);
}

// Send a stop sequence
//
// Modified 7-21-04 to correctly set SDA to be an output
// 
void cm_Stop(void)
{
	cm_Delay(10);//by jgw for delay to avoid i2c dead because of too fast
	CM_DATA_OUT;                         // Data line must be an output to send a stop sequence
	cm_Clocklow();
	CM_DATA_LO;
	cm_Delay(4);
	cm_Clockhigh();
	cm_Delay(8);
	CM_DATA_HI;
	cm_Delay(4);
}

// Write a byte
//
// Returns 0 if write successed, 1 if write fails failure
//
// Modified 7-21-04 to correctly control SDA
// 
uint8_t cm_Write(uint8_t ucData)
{
    uint8_t i;

	cm_Delay(10);//by jgw for delay to avoid i2c dead because of too fast
    CM_DATA_OUT;                         // Set data line to be an output
    for(i=0; i<8; i++) {                 // Send 8 bits of data
        cm_Clocklow();
        if (ucData&0x80) CM_DATA_HI;
        else             CM_DATA_LO;
        cm_Clockhigh();
        ucData = ucData<<1;
    }
    cm_Clocklow();

    // wait for the ack
    CM_DATA_IN;                      // Set data line to be an input
    cm_Delay(8);
    cm_Clockhigh();
    while(i>1) {                    // loop waiting for ack (loop above left i == 8)
        cm_Delay(2);
        if (CM_DATA_RD) i--;        // if SDA is high level decrement retry counter
        else i = 0;
    }      
    cm_Clocklow();
    CM_DATA_OUT;                     // Set data line to be an output
    return i;
}

// Send a ACK or NAK or to the device
void cm_AckNak(uint8_t ucAck)
{
	cm_Delay(10);//by jgw for delay to avoid i2c dead because of too fast
	CM_DATA_OUT;                         // Data line must be an output to send an ACK
	cm_Clocklow();
	if (ucAck) CM_DATA_LO;               // Low on data line indicates an ACK
	else       CM_DATA_HI;               // High on data line indicates an NACK
	cm_Delay(2);
	cm_Clockhigh();
	cm_Delay(8);
	cm_Clocklow();
}

//     Read a byte from device, MSB
//
// Modified 7-21-04 to correctly control SDA
// 
uint8_t cm_Read(void)
{
	uint8_t i;
	uint8_t rByte = 0;	
	CM_DATA_IN;                          // Set data line to be an input
	CM_DATA_HI;
	for(i=0x80; i; i=i>>1)
	{
		cm_ClockCycle();
		if (CM_DATA_RD) rByte |= i;
		cm_Clocklow();
	}
	CM_DATA_OUT;                         // Set data line to be an output
	return rByte;
}

void cm_WaitClock(uint8_t loop)
{
	uint8_t i, j;
	
	CM_DATA_LO;
	for(j=0; j<loop; j++) {
		cm_Start();
		for(i = 0; i<15; i++) cm_ClockCycle();
		cm_Stop();
	}
}

// Send a command
//
uint8_t cm_SendCommand(uint8_t * pucInsBuff)
{
    uint8_t i, ucCmd;
	
    i = CM_START_TRIES;
    ucCmd = (pucInsBuff[0]&0x0F)|CM_PORT_CFG.ucChipSelect;
    while (i) {
        cm_Start();
        if (cm_Write(ucCmd) == 0) break;
        if (--i == 0) return FAIL_CMDSTART;
    }
	
    for(i = 1; i< 4; i++) {
        if (cm_Write(pucInsBuff[i]) != 0) return FAIL_CMDSEND;
    }
    return SUCCESS;
}

uint8_t cm_ReceiveData(uint8_t * pucRecBuf, uint8_t ucLen)
{
    int i;

    for(i = 0; i < (ucLen-1); i++) {
        pucRecBuf[i] = cm_Read();
        cm_AckNak(TRUE);
    }
    pucRecBuf[i] = cm_Read();
    cm_AckNak(FALSE);
    cm_Stop();
    return SUCCESS;
}

uint8_t cm_SendData(uint8_t * pucSendBuf, uint8_t ucLen)
{
	int i;
	for(i = 0; i< ucLen; i++) {
		if (cm_Write(pucSendBuf[i])==1) return FAIL_WRDATA;
	}
	cm_Stop();
	
	return SUCCESS;
}


// Send a command byte
//
uint8_t cm_SendCmdByte(uint8_t ucCommand)
{
    uint8_t i, ucCmd;
	
    i = CM_START_TRIES;

    ucCmd = (ucCommand&0x0F)|CM_PORT_CFG.ucChipSelect;
    while (i) {
      cm_Start();
	    if (cm_Write(ucCmd) == 0) break;
	    if (--i == 0) return FAIL_CMDSTART;
    }

    return SUCCESS;
}