//******************************************************************************
//  MSP-FET430P140 Demo - I2C, Master Interface to 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 Inc.
//  Feb 2005
//  Built with IAR Embedded Workbench Version: 3.21A
//******************************************************************************

#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
}