151 lines
3.9 KiB
C
151 lines
3.9 KiB
C
#include "msp430.h"
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#include <stdlib.h>
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#include <stdbool.h>
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#define MIDC 3822
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#define DFLAT 3608
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#define D 3405
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#define EFLAT 3214
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#define E 3034
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#define F 2863
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#define GFLAT 2703
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#define G 2551
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#define AFLAT 2408
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#define A 2273
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#define BFLAT 2145
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#define B 2025
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#define TENC 1911
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#define NONE 0
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#define LED1 BIT0
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#define BUTTON BIT3
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#define OUTPUT BIT6
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// constants used for unit conversions in timer interrupt
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// CSINT should be 256^2 / 10 000 = 65 536 / 10 000 = 6
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// USINT should be 60 000
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#define CSUS 10000 // microseconds (us) in a centisecond (cs)
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#define CSINT 6 // centiseconds storable in int of microseconds
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#define USINT 60000 // CSINT in microseconds
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#define MAXNOTES 0xA2 // 162 (not enough RAM to allocate any more to rec)
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// pitch is index of scale array
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// length is in centiseconds
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// max length of note is 0xFFF = approx. 41 seconds
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typedef struct {
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unsigned int pitch : 4;
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unsigned int length : 12;
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} Note;
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unsigned int scale[16] = {
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NONE, MIDC, DFLAT, D, EFLAT, E, F,
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GFLAT, G, AFLAT, A, BFLAT, B, TENC,
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NONE, NONE // should not be used
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};
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Note rec[MAXNOTES];
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volatile bool recording = true;
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volatile unsigned int notes = 1;
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volatile unsigned int us = 0;
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volatile unsigned int cs = 0;
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void play(unsigned int pitch) {
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if (pitch != 0) {
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CCR0 = scale[pitch];
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CCR1 = scale[pitch] / 2; // max volume
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} else {
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CCR0 = 0xFFFF; // cannot count to 0; set to max
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CCR1 = 0;
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}
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}
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void playback() {
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for (unsigned int i = 0; i < notes; i++) {
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play(rec[i].pitch);
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for (unsigned int j = 0; j < rec[i].length; j++) {
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__delay_cycles(CSUS);
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}
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}
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}
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void save_length(unsigned int position) {
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rec[position].length = cs + (us + TAR)/CSUS;
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cs = us = TAR = 0; // reset all counts
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}
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void end_record() {
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recording = false;
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P1OUT &= ~LED1;
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TACCTL0 &= ~CCIE;
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play(0);
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}
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void record() {
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TAR = 0;
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P1OUT |= LED1;
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while (recording && notes < MAXNOTES) {
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unsigned int pitch = P2IN & 0xF;
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if (pitch != rec[notes - 1].pitch) {
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save_length(notes - 1);
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rec[notes].pitch = pitch;
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play(pitch);
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notes++;
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}
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__delay_cycles(1000);
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}
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end_record();
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}
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void main(void) {
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WDTCTL = WDTPW + WDTHOLD; // Stop WDT
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P2DIR = 0; // P2 all input
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P2REN = 0xF; // P2 inputs resistor enable
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P2OUT = 0; // P2 resistor pulldown
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P1DIR = OUTPUT | LED1; // P1.6, P1.0 output (P1.3 input)
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P1SEL |= OUTPUT; // P1.6 to TA0.1
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P1REN = BUTTON; // button resistor enable
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P1IE = BUTTON; // enable button interrupt
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CCTL1 = OUTMOD_7; // CCR1 reset/set
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TACTL = TASSEL_2 | MC_1; // SMCLK (1 MHz) count up to CCRO
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TACCTL0 = CCIE; // enable clock interrupt
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__enable_interrupt();
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record();
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__bis_SR_register(LPM0_bits);
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}
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#if defined(__TI_COMPILER_VERSION__)
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#pragma vector=TIMER0_A0_VECTOR
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__interrupt void timer0_a0_isr(void)
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#else
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void __attribute__ ((interrupt(TIMER0_A0_VECTOR))) timer0_a0_isr (void)
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#endif
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{
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unsigned int us_left = USINT - us; // count up to USINT microseconds in us
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if (us_left < TACCR0) {
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cs += CSINT; // add centiseconds to cs count
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us = TACCR0 - us_left; // save overflow
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} else {
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us += TACCR0; // add microseconds to us count
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}
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TACCTL0 &= ~CCIFG; // set interrupt flag to 0
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}
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#if defined(__TI_COMPILER_VERSION__)
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#pragma vector=PORT1_VECTOR
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__interrupt void port1_isr(void)
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#else
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void __attribute__ ((interrupt(PORT1_VECTOR))) port1_isr (void)
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#endif
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{
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if (recording) {
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save_length(notes);
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end_record();
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}
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playback();
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P1IFG &= ~BUTTON; // set interrupt flag to 0
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}
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