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//******************************************************************************
// MSP430F22x4 Demo - USCI_B0 I2C Master Interface to DAC8571, Write
//
// Description: Using UCB0TXIE, a continuous sine wave is output to the
// external DAC using a 16-point look-up table. Only one start condition
// is executed. Data is handled by the ISR and the CPU is normally in LPM0.
// ACLK = n/a, MCLK = SMCLK = BRCLK = default DCO = ~1.2MHz
//
// MSP430F22x4 DAC8571
// ------------------ ------------
// -|XIN P3.1/UCB0SDA|<--------------->|SDA |
// | P3.2/UCB0SCL|---------------->|SCL I2C |
// -|XOUT | | SLAVE |
// | I2C MASTER | GND|A0 |
//
//
// DAC8571 I2C address = 0x4C (A0 = GND)
//
// Andreas Dannenberg
// Texas Instruments Inc.
// March 2006
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.41A
//******************************************************************************
#include "msp430x22x4.h"
const unsigned char Sine_Tab[] = // 16 Point 16-bit Sine Table
{
0xFF, // MSB Word 0
0xFF, // LSB
0xF6, // MSB Word 1
0x40, // LSB
0xDA, // MSB Word 2
0x81, // LSB
0xB0, // MSB Word 3
0xFA, // LSB
0x7F, // MSB Word 4
0xFF, // LSB
0x4F, // MSB Word 5
0x03, // LSB
0x25, // MSB Word 6
0x7C, // LSB
0x09, // MSB Word 7
0xBD, // LSB
0x00, // MSB Word 8
0x00, // LSB
0x09, // MSB Word 9
0xBD, // LSB
0x25, // MSB Word 10
0x7C, // LSB
0x4F, // MSB Word 11
0x03, // LSB
0x7F, // MSB Word 12
0xFE, // LSB
0xB0, // MSB Word 13
0xFA, // LSB
0xDA, // MSB Word 14
0x81, // LSB
0xF6, // MSB Word 15
0x40 // LSB
};
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop Watchdog Timer
P3SEL |= 0x06; // Assign I2C pins to USCI_B0
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_2 + UCSWRST; // Use SMCLK, keep SW reset
UCB0BR0 = 12; // fSCL = SMCLK/12 = ~100kHz
UCB0BR1 = 0;
UCB0I2CSA = 0x4c; // Set slave address
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
IE2 |= UCB0TXIE; // Enable TX ready interrupt
UCB0CTL1 |= UCTR + UCTXSTT; // I2C TX, start condition
UCB0TXBUF = 0x010; // Write DAC control byte
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
}
// USCI_B0 Data ISR
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
static unsigned char ByteCtr;
UCB0TXBUF = Sine_Tab[ByteCtr++]; // Transmit data byte
ByteCtr &= 0x1f; // Do not exceed table
}
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