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-rw-r--r--quantum/audio/driver_chibios_pwm_software.c164
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diff --git a/quantum/audio/driver_chibios_pwm_software.c b/quantum/audio/driver_chibios_pwm_software.c
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1/* Copyright 2020 Jack Humbert
2 * Copyright 2020 JohSchneider
3 *
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
16 */
17
18/*
19Audio Driver: PWM
20
21the duty-cycle is always kept at 50%, and the pwm-period is adjusted to match the frequency of a note to be played back.
22
23this driver uses the chibios-PWM system to produce a square-wave on any given output pin in software
24- a pwm callback is used to set/clear the configured pin.
25
26 */
27#include "audio.h"
28#include "ch.h"
29#include "hal.h"
30
31#if !defined(AUDIO_PIN)
32# error "Audio feature enabled, but no pin selected - see docs/feature_audio under the ARM PWM settings"
33#endif
34extern bool playing_note;
35extern bool playing_melody;
36extern uint8_t note_timbre;
37
38static void pwm_audio_period_callback(PWMDriver *pwmp);
39static void pwm_audio_channel_interrupt_callback(PWMDriver *pwmp);
40
41static PWMConfig pwmCFG = {
42 .frequency = 100000, /* PWM clock frequency */
43 // CHIBIOS-BUG? can't set the initial period to <2, or the pwm (hard or software) takes ~130ms with .frequency=500000 for a pwmChangePeriod to take effect; with no output=silence in the meantime
44 .period = 2, /* initial PWM period (in ticks) 1S (1/10kHz=0.1mS 0.1ms*10000 ticks=1S) */
45 .callback = pwm_audio_period_callback,
46 .channels =
47 {
48 // software-PWM just needs another callback on any channel
49 {PWM_OUTPUT_ACTIVE_HIGH, pwm_audio_channel_interrupt_callback}, /* channel 0 -> TIMx_CH1 */
50 {PWM_OUTPUT_DISABLED, NULL}, /* channel 1 -> TIMx_CH2 */
51 {PWM_OUTPUT_DISABLED, NULL}, /* channel 2 -> TIMx_CH3 */
52 {PWM_OUTPUT_DISABLED, NULL} /* channel 3 -> TIMx_CH4 */
53 },
54};
55
56static float channel_1_frequency = 0.0f;
57void channel_1_set_frequency(float freq) {
58 channel_1_frequency = freq;
59
60 if (freq <= 0.0) // a pause/rest has freq=0
61 return;
62
63 pwmcnt_t period = (pwmCFG.frequency / freq);
64 pwmChangePeriod(&AUDIO_PWM_DRIVER, period);
65
66 pwmEnableChannel(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1,
67 // adjust the duty-cycle so that the output is for 'note_timbre' duration HIGH
68 PWM_PERCENTAGE_TO_WIDTH(&AUDIO_PWM_DRIVER, (100 - note_timbre) * 100));
69}
70
71float channel_1_get_frequency(void) { return channel_1_frequency; }
72
73void channel_1_start(void) {
74 pwmStop(&AUDIO_PWM_DRIVER);
75 pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
76
77 pwmEnablePeriodicNotification(&AUDIO_PWM_DRIVER);
78 pwmEnableChannelNotification(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1);
79}
80
81void channel_1_stop(void) {
82 pwmStop(&AUDIO_PWM_DRIVER);
83
84 palClearLine(AUDIO_PIN); // leave the line low, after last note was played
85
86#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE)
87 palClearLine(AUDIO_PIN_ALT); // leave the line low, after last note was played
88#endif
89}
90
91// generate a PWM signal on any pin, not necessarily the one connected to the timer
92static void pwm_audio_period_callback(PWMDriver *pwmp) {
93 (void)pwmp;
94 palClearLine(AUDIO_PIN);
95
96#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE)
97 palSetLine(AUDIO_PIN_ALT);
98#endif
99}
100static void pwm_audio_channel_interrupt_callback(PWMDriver *pwmp) {
101 (void)pwmp;
102 if (channel_1_frequency > 0) {
103 palSetLine(AUDIO_PIN); // generate a PWM signal on any pin, not necessarily the one connected to the timer
104#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE)
105 palClearLine(AUDIO_PIN_ALT);
106#endif
107 }
108}
109
110static void gpt_callback(GPTDriver *gptp);
111GPTConfig gptCFG = {
112 /* a whole note is one beat, which is - per definition in musical_notes.h - set to 64
113 the longest note is BREAVE_DOT=128+64=192, the shortest SIXTEENTH=4
114 the tempo (which might vary!) is in bpm (beats per minute)
115 therefore: if the timer ticks away at .frequency = (60*64)Hz,
116 and the .interval counts from 64 downwards - audio_update_state is
117 called just often enough to not miss anything
118 */
119 .frequency = 60 * 64,
120 .callback = gpt_callback,
121};
122
123void audio_driver_initialize(void) {
124 pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
125
126 palSetLineMode(AUDIO_PIN, PAL_MODE_OUTPUT_PUSHPULL);
127 palClearLine(AUDIO_PIN);
128
129#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE)
130 palSetLineMode(AUDIO_PIN_ALT, PAL_MODE_OUTPUT_PUSHPULL);
131 palClearLine(AUDIO_PIN_ALT);
132#endif
133
134 pwmEnablePeriodicNotification(&AUDIO_PWM_DRIVER); // enable pwm callbacks
135 pwmEnableChannelNotification(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1);
136
137 gptStart(&AUDIO_STATE_TIMER, &gptCFG);
138}
139
140void audio_driver_start(void) {
141 channel_1_stop();
142 channel_1_start();
143
144 if (playing_note || playing_melody) {
145 gptStartContinuous(&AUDIO_STATE_TIMER, 64);
146 }
147}
148
149void audio_driver_stop(void) {
150 channel_1_stop();
151 gptStopTimer(&AUDIO_STATE_TIMER);
152}
153
154/* a regular timer task, that checks the note to be currently played
155 * and updates the pwm to output that frequency
156 */
157static void gpt_callback(GPTDriver *gptp) {
158 float freq; // TODO: freq_alt
159
160 if (audio_update_state()) {
161 freq = audio_get_processed_frequency(0); // freq_alt would be index=1
162 channel_1_set_frequency(freq);
163 }
164}