fet140_i2c_dac8571_rw_ifg.c

msp430f14x 系列片内外设的实例代码

//******************************************************************************
//  MSP-FET430P140 Demo - I2C Master Interface DAC8571 Read / Write   
//
//  Description: I2C communication with a DAC8571 in read and write mode is 
//  demonstrated. MSP430 writes a 0x00 to the DAC to initialize communication
//  and then reads the value from the DAC, increments it by 1, and Transmits
//  it back to the DAC8571 in a repetitive manner to generate a ramp  
//  ACLK = n/a, MCLK = SMCLK = default DCO ~ 800k, SCL = SMCLK/10
//  //* MSP430F169 Device Required*//
//
//                                 /|\  /|\
//                  DAC8571        10k  10k     MSP430F169
//                    slave         |    |        master           
//              -----------------|  |    |  ----------------- 
//             |             SDA |<-|---+->|P3.1             |
//             |                 |  |      |                 |
//             |                 |  |      |                 |
//      GND <--|A0           SCL |<-+----->|P3.3             |
//             |                 |         |                 |
//             |                 |         |                 |
//             |              Vdd|<---+--->|Vcc              |
//             |             Vref|<---|    |                 |
//             |              GND|<------->|GND              |
//             |                 |         |                 |
//
//
//   DAC8571 I2C address = 0x4C (A0 = GND)     
//
//
//  H. Grewal
//  Texas Instruments
//  Sep 2004
//  Updated for IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include  "msp430x16x.h"

void Commstart (void);
void RXBytes (void);
void TXBytes (void);
volatile unsigned int i;

void main(void)
{
  WDTCTL = WDTPW | WDTHOLD;            // Disable the Watchdog.
  P3SEL |= 0x0a;                       // Assign I2C pins to module
  U0CTL |= I2C + SYNC;                 // Switch USART0 to I2C mode
  U0CTL &= ~I2CEN;                     // Recommended init procedure
  I2CTCTL = I2CSSEL_2;                 // SMCLK
  I2CNDAT = 0x03;                      // Transmit Three byte                        
  I2CSA = 0x4C;                        // Slave address
  U0CTL |= I2CEN;                      // Enable I2C, 7 bit addr,
  Commstart();                         // MSP430 sends a 0x00 to the DAC
  while(1)
  {
    RXBytes();                         // RX 3 Bytes (MSB, LSB, Control)
    TXBytes();                         // TX 3 Bytes (Control, MSB, LSB)
  }  
}


void Commstart (void)
{  
  U0CTL |= MST;                        // Master mode
  I2CTCTL |= I2CSTT+I2CSTP+I2CTRX;     // Initiate transfer
  while ((I2CIFG & TXRDYIFG) == 0);    // Wait for transmitter to be ready
  I2CDRB = 0x10;                       // Load  Control Byte
  while ((I2CIFG & TXRDYIFG) == 0);    // Wait for transmitter to be ready
  I2CDRB = 0x00;                       // Load  MSByte
  while ((I2CIFG & TXRDYIFG) == 0);    // Wait for transmitter to be ready
  I2CDRB = 0x00;                       // Load  LSByte
  while ((I2CTCTL & I2CSTP) == 0x02);  // To prevent Arbitration Lost
}

void RXBytes (void)
{
  unsigned char ctlbyte;
  U0CTL |= MST;                        // Master mode
  I2CTCTL = I2CSTT+I2CSTP;             // Initiate transfer
  while ((I2CIFG & RXRDYIFG) == 0);    // Wait for Receiver to be ready
  i = I2CDRB;                          // Receive MSByte from DAC
  i = i << 8;
  while ((I2CIFG & RXRDYIFG) == 0);    // Wait for Receiver to be ready
  i = i + I2CDRB;                      // Receive LSByte from DAC
  while ((I2CIFG & RXRDYIFG) == 0);    // Wait for Receiver to be ready
  ctlbyte = I2CDRB;                    // Receive ControlByte from DAC
  while ((I2CTCTL & I2CSTP) == 0x02);  // Wait for Stop Condition
}

void TXBytes (void)
{  
  i = i + 1;
  U0CTL |= MST;                        // Master mode
  I2CTCTL |= I2CSTT+I2CSTP+I2CTRX;     // Initiate transfer
  while ((I2CIFG & TXRDYIFG) == 0);    // Wait for transmitter to be ready
  I2CDRB = 0x10;                       // Load  Control Byte
  while ((I2CIFG & TXRDYIFG) == 0);    // Wait for transmitter to be ready
  I2CDRB = i >> 8;                     // Load  MSByte
  while ((I2CIFG & TXRDYIFG) == 0);    // Wait for transmitter to be ready
  I2CDRB = i & 0x00FF;                 // Load  LSByte
  while ((I2CTCTL & I2CSTP) == 0x02);  // Wait for Stop Condition
}