78 lines
3.3 KiB
C
78 lines
3.3 KiB
C
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/*------------------------------------------------------------------------------
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* File: Lab10_D3.c (CPE 325 Lab10 Demo code)
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* Function: Sinusoidal wave with DAC (MPS430FG4618)
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* Description: This C program reconstructs the sinusoidal wave (y=1.25(1+sin(x)))
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* from the samples using DAC and outputs at P6.6. WDT is used to
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* give an interrupt for every ~0.064ms to wake up the CPU and
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* feed the DAC with new value. Connect the oscilloscope to P6.6
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* to observe the signal. The interval used to read the samples
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* controls the frequency of output signal.
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* Clocks: ACLK = LFXT1 = 32768Hz, MCLK = SMCLK = DCO = default (~1MHz)
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* An external watch crystal between XIN & XOUT is required for ACLK
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*
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* MSP430xG461x
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* -------------------
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* /|\| XIN|-
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* | | | 32kHz
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* --|RST XOUT|-
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* | |
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* | DAC0/P6.6|--> sine (10Hz)
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* | |
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* Input: None
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* Output: Sinusoidal wave with 10Hz frequency at P6.6
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* Author: Aleksandar Milenkovic, milenkovic@computer.org
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* Max Avula, ma0004@uah.edu
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*------------------------------------------------------------------------------*/
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#include <msp430.h>
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#include <sawtooth.h> /*512 samples are stored in this table */
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#include <sine_lut_512.h> /*256 samples are stored in this table */
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#define SW1 ((P1IN&BIT0)==0) // Switch 1 status
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#define SW2 ((P1IN&BIT1)==0) // Switch 2 status
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void TimerA_setup(void) {
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TACTL = TASSEL_2 + MC_1; // SMCLK, up mode
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TACCR0 = 164; // Sets Timer Freq (1048576*0.1sec/256)
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TACCTL0 = CCIE; // CCR0 interrupt enabled
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}
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void DAC_setup(void) {
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ADC12CTL0 = REF2_5V + REFON; // Turn on 2.5V internal ref volage
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unsigned int i = 0;
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for (i = 50000; i > 0; i--); // Delay to allow Ref to settle
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DAC12_0CTL = DAC12IR + DAC12AMP_5 + DAC12ENC; //Sets DAC12
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}
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void main(void) {
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P1DIR &= ~BIT0; // Set P1.1 to output direction
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P1DIR &= ~BIT1; // Set P1.0 to output direction
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FLL_CTL0 |= DCOPLUS + XCAP18PF; // DCO+ set, freq = xtal x D x N+1
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SCFI0 |= FN_4 + FLLD_2; // DCO range control, multiplier D
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SCFQCTL = 63; // (61+1) x 32768 x 2 = 4.19 MHz
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WDTCTL = WDTPW + WDTHOLD; // Stop WDT
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TimerA_setup(); // Set timer to uniformly distribute the samples
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DAC_setup(); // Setup DAC
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unsigned int i = 0;
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unsigned int o = 0;
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while (1) {
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__bis_SR_register(LPM0_bits + GIE); // Enter LPM0, interrupts enabled
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if(SW1){
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o = sine[i];
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}
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else{
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o = sawtooth[i];
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}
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if(!SW2){
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o = o>>1;
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}
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DAC12_0DAT = o;
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i=(i+1)%512;
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}
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}
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#pragma vector = TIMERA0_VECTOR
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__interrupt void TA0_ISR(void) {
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__bic_SR_register_on_exit(LPM0_bits); // Exit LPMx, interrupts enabled
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}
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