i2cdrive.c

Philips LPC932 I2C 接口源程序

#include "i2cexprt.h"
/* Immediate data to write into I2CON */
/* CRSEL = 0 -> CLK determined by I2SCLH / L */
#define GENERATE_STOP 0x54 /* STO=1, STA=0, SI=0 */
#define RELEASE_BUS_ACK 0x44 /* STO=STA=SI=0, AA=1 */
#define RELEASE_BUS_NOACK 0x40 /* STO=STA=SI=AA=0 */
#define RELEASE_BUS_STA 0x64 /* (rep)START, STA=1 */
static I2C_TRANSFER *tfr; /* Ptr to active trf block */
static I2C_MESSAGE *msg; /* ptr to active msg block */
static BYTE msgCount; /* Nr of messages to sent */
static BYTE dataCount; /* bytes send/received */
void I2C_Interrupt(void) interrupt 6 using 1
{
    switch(I2STAT)
    {
        case 0x00: /* Bus Error has occured */
            I2CON = GENERATE_STOP;
        break;
        case 0x08:
        case 0x10:
            I2DAT = msg->address;
            I2CON = RELEASE_BUS_ACK;
        break;
        case 0x18:
        case 0x28:
            if (dataCount < msg->nrBytes)
            {
                I2DAT = msg->buf[dataCount++];
                I2CON = RELEASE_BUS_ACK;
            }
            else
            {
                if (msgCount < tfr->nrMessages)
                {
                    dataCount = 0;
                    msg = tfr->p_message[msgCount++];
                    I2CON = RELEASE_BUS_STA;
                }
                else
                {
                    I2CON = GENERATE_STOP;
                    I2C_Ready(I2C_OK, msgCount);
                }
            }
        break;
        case 0x20:
        case 0x48:
            I2C_Ready(I2C_NACK_ON_ADDRESS, msgCount);
            I2CON = GENERATE_STOP;
        break;
        case 0x30:
            I2C_Ready(I2C_NACK_ON_DATA, msgCount);
            I2CON = GENERATE_STOP;
        break;
        case 0x38:
            I2CON = RELEASE_BUS_STA;
        break;
        case 0x40:
            if (msg->nrBytes == 1)
                I2CON = RELEASE_BUS_NOACK;
            else
                I2CON = RELEASE_BUS_ACK;
        break;
        case 0x50:
            msg->buf[dataCount++] = I2DAT;
            if (dataCount + 1 == msg->nrBytes)
                I2CON = RELEASE_BUS_NOACK;
            else
                I2CON = RELEASE_BUS_ACK;
        break;
        case 0x58:
            msg->buf[dataCount] = I2DAT;
            if (msgCount < tfr->nrMessages)
            {
                dataCount = 0;
                msg = tfr->p_message[msgCount++];
                I2CON = RELEASE_BUS_STA;
            }
            else
            {
                I2CON = GENERATE_STOP;
                I2C_Ready(I2C_OK, msgCount);
            }
        break;
        default: break;
    }
}
void I2C_Init(void)
/*****************/
{
    // Fpclk = 7.373 Mhz internal oscillator
    // I2c speed = Fpclk / (2*(I2SCLH+I2SCLL)
    P1M1 |= 0x0C; /* P1.2 and P1.3 to open drain */
    P1M2 |= 0x0C;
    I2ADR = 0x26; /* default slave address */
    I2SCLH = 19; /* speed ~100KHz, 50% duty */
    I2SCLL = 19;
    I2CON = RELEASE_BUS_ACK; /* enable I2C hardware */
    EI2C = 1; /* enable I2C interrupt */
}
void I2C_Transfer(I2C_TRANSFER *p)
{
    tfr = p;
    msgCount = 0;
    dataCount = 0;
    msg = tfr->p_message[msgCount++];
    I2CON = RELEASE_BUS_STA;
}