mirror of
https://github.com/sjlongland/atinysynth.git
synced 2025-09-27 10:53:29 +10:00
Stuart Longland
6ddaad18f2
This is a work-in-progress, but we're now able to play some notes by pressing keys.
111 lines
3.1 KiB
C
111 lines
3.1 KiB
C
/*!
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* Polyphonic synthesizer for microcontrollers: Atmel ATTiny85 port.
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* (C) 2016 Stuart Longland
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#include "synth.h"
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#include "adckbd.h"
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#include <string.h>
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#include <avr/io.h>
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#include <util/delay.h>
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#include <avr/interrupt.h>
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struct voice_ch_t poly_voice[16];
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struct poly_synth_t synth;
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int main(void) {
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/* Initialise configuration */
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memset(poly_voice, 0, sizeof(poly_voice));
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synth.voice = poly_voice;
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synth.enable = 0;
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synth.mute = 0;
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adckbd_init();
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/* Enable output on PB4 (PWM out) */
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DDRB |= (1 << 4) | (1 << 0) | (1 << 1) | (1 << 2);
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PORTB &= ~((1 << 4) | (1 << 0) | (1 << 1) | (1 << 2));
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/* Timer 1 configuration for PWM */
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OCR1B = 128; /* Initial PWM value */
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OCR1C = 255; /* Maximum PWM value */
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TCCR1 = (1 << CS10); /* No prescaling, max speed */
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GTCCR = (1 << PWM1B) /* Enable PWM */
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| (2 << COM1B0); /* Clear output bit on match */
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/* Timer 0 configuration for sample rate interrupt */
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TCCR0A = (2 << WGM01); /* CTC mode */
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TCCR0B = (1 << CS01); /* 1/8 prescaling */
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/* Sample rate */
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OCR0A = (uint8_t)((uint32_t)F_CPU / (8*(uint32_t)SYNTH_FREQ));
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TIMSK |= (1 << OCIE0A); /* Enable interrupts */
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/* Configure the synthesizer */
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voice_wf_set_triangle(&poly_voice[0].wf, 523, 63);
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voice_wf_set_triangle(&poly_voice[1].wf, 659, 63);
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voice_wf_set_triangle(&poly_voice[2].wf, 784, 63);
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voice_wf_set_triangle(&poly_voice[3].wf, 880, 63);
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adsr_config(&poly_voice[0].adsr,
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100, 0, 10, 10, 10, 10, 255, 192);
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adsr_config(&poly_voice[1].adsr,
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100, 0, 10, 10, 10, 10, 255, 192);
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adsr_config(&poly_voice[2].adsr,
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100, 0, 10, 10, 10, 10, 255, 192);
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adsr_config(&poly_voice[3].adsr,
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100, 0, 10, 10, 10, 10, 255, 192);
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synth.enable = 0x0;
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sei();
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while(1) {
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PORTB ^= (1 << 0);
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if (adckbd_now & ADCKBD_CHANGED) {
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uint8_t btn = 0;
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uint8_t voice = 0;
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for (btn = ADCKBD_PRESSED(0), voice = 0;
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btn & ADCKBD_ALL;
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btn <<= 1, voice++) {
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PORTB ^= (1 << 2);
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/* Is it pressed now? */
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if (!(adckbd_now & btn))
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continue;
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/* Was it pressed before? */
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if (!(adckbd_diff & btn))
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continue;
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adsr_reset(&poly_voice[voice].adsr);
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synth.enable |= btn;
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/* Acknowledge key */
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adckbd_now &= ~btn;
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}
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/* Acknowledge changes */
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adckbd_now &= ~ADCKBD_CHANGED;
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PORTB ^= (1 << 1);
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}
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}
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return 0;
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}
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ISR(TIM0_COMPA_vect) {
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int8_t s = poly_synth_next(&synth);
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OCR1B = s + 128;
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}
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