Lpc2000

hi
just after initialisation of I2c if i send a data then waveform should be observed at SCD/SDA even if there is no I2C device connected. am I right?
I donot get any waveform.
 
Santosh Jha
 
 


peterburdine <lordofdawn@hotmail.com> wrote:

--- In lpc2000@yahoogroups.com, "jha_santosh_kr2005"
<jha_santosh_kr2005@y...> wrote:
> 
> Hi,
> I am desperately trying to communicate with RTC pCF8583 using I2C of 
> lpc2106 using Keil C compiler.But I am unable to start the I2C.
> 
> Pl. help if u have time.
> Regards,
> Santosh Jha

Here is an outline of a polled i2c function, there is more that goes
around this, but you can probably figure the rest out:


#define I2CONSET       (*((volatile unsigned char *) 0xE001C000))
#define I2STAT         (*((volatile unsigned char *) 0xE001C004))
#define I2DAT          (*((volatile unsigned char *) 0xE001C008))
#define I2ADR          (*((volatile unsigned char *) 0xE001C00C))
#define I2SCLH         (*((volatile unsigned short*) 0xE001C010))
#define I2SCLL         (*((volatile unsigned short*) 0xE001C014))
#define I2CONCLR       (*((volatile unsigned char *) 0xE001C018))


#define ENABLE_I2C_PINS      ( PINSEL0 = ((PINSEL0&0xFFFFFF0F) |
PINSEL0_02_SCL | PINSEL0_03_SDA ) )
#define ENABLE_I2C_IRQ  ( VICIntEnable = (0x1 << I2C_IRQ) )
#define DISABLE_I2C_IRQ ( VICIntEnClr  = (0x1 << I2C_IRQ) )
#define ENABLE_I2C_AA      ( I2CONSET |= (0x1 << 2))
#define DISABLE_I2C_AA      ( I2CONCLR = (0x1 << 2))
#define I2C_BIT_RATE(rate)  (I2SCLH = I2SCLL =
((Uint16)(PERIPH_FREQ/2/rate)+10))
#define I2C_SEND_START      (I2CONSET |= (0x1 << 5))
#define I2C_SEND_STOP      (I2CONSET = (0x1 << 4))
#define I2C_CLR_START      (I2CONCLR = (0x1 << 5))
#define I2C_CLR_SI            (I2CONCLR = (0x1 << 3))

void i2c_transfer (void) {
      Uint8 code;
      Uint8 transferComplete = 0;
      i2c_pos = 0;      
      
      while(!transferComplete) {
            code = I2STAT;
            switch(code) {
                  /***** MASTER TX MODE *****/
                  case 0x08:  // First Start Transmitted
                  case 0x10:      // Repeated Start
                        // Write address and tell if it is read or write
                        I2DAT = (i2c_address << 1) | i2c_RdnWr;
                        I2CONCLR = (0x1 << 3);            // Clear SI
                        break;
                  case 0x18:      // Start + Wr sent, ACK received
                  case 0x20:      // Start + Wr sent, Not ACK received
                  case 0x28:  // Data byte sent, ACK recieved
                  case 0x30:  // Data byte sent, Not Ack received
                        if(i2c_bytesRemaining > 0) {
                              I2DAT = i2c_buffer[i2c_pos++];
                              i2c_bytesRemaining--;
                              I2CONCLR = (0x1 << 5);
                        }
                        else if(i2c_rxBytesRemaining == 0) {
                              I2C_SEND_STOP; // Send Stop
                              I2CONCLR = (0x1 << 5);
                              transferComplete = 1;
                        }
                        else { // Change from master_tx to master_rx
                              i2c_RdnWr = (~i2c_RdnWr)&0x1;
                              i2c_pos = 0;
                              i2c_rxWrPos = 0;
                              i2c_rxComplete = 0;
                              I2C_SEND_START;
                        }
                        I2CONCLR = (0x1 << 3);            // Clear SI
                        break;            
                  case 0x38:      // Arbitration Lost, try again 
                        I2C_SEND_START;
                        I2CONCLR = (0x1 << 3);            // Clear SI      
                        break;
                  /***** MASTER RX MODE *****/      
                  case      0x40:      // SLA+R HAS BEEN SENT; ACK RECEIVED                        
                        if(i2c_rxBytesRemaining != 0)
                              ENABLE_I2C_AA;
                        else
                              DISABLE_I2C_AA;                        
                        I2CONCLR = (0x1 << 3) | (0x1 << 5);      // Clear SI and START
                        break;
                  case      0x48: // SLA+R has been send; not ack received
                        // Try again
                        I2C_SEND_START;
                        I2C_CLR_SI;
                        break;
                        
                  case      0x50:      // DATA BYTE RECEIVED, ACK RETURNED
                        i2c_rxBuffer[i2c_rxWrPos] = I2DAT;
                        i2c_rxWrPos++;
                        i2c_rxBytesRemaining--;
                        if(i2c_rxBytesRemaining != 0)
                              ENABLE_I2C_AA;
                        else
                              DISABLE_I2C_AA;
                        I2CONCLR = (0x1 << 3) | (0x1 << 5);      // Clear SI and START
                        break;
                  case      0x58:      // DATA BYTE RECEIVED; NOT ACT RETURNED
                        i2c_rxComplete = 1; // Done receiving all requested data
                        transferComplete = 1;
                        I2C_CLR_START;
                        I2C_SEND_STOP;
                        I2C_CLR_SI;
                        break;                                                            
            }
      }
}




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