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Diffstat (limited to 'quantum/audio/driver_chibios_pwm_hardware.c')
-rw-r--r--quantum/audio/driver_chibios_pwm_hardware.c144
1 files changed, 0 insertions, 144 deletions
diff --git a/quantum/audio/driver_chibios_pwm_hardware.c b/quantum/audio/driver_chibios_pwm_hardware.c
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--- a/quantum/audio/driver_chibios_pwm_hardware.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 specific output pins that are connected to the PWM hardware.
24The hardware directly toggles the pin via its alternate function. see your MCUs data-sheet for which pin can be driven by what timer - looking for TIMx_CHy and the corresponding alternate function.
25
26 */
27
28#include "audio.h"
29#include "ch.h"
30#include "hal.h"
31
32#if !defined(AUDIO_PIN)
33# error "Audio feature enabled, but no pin selected - see docs/feature_audio under the ARM PWM settings"
34#endif
35
36extern bool playing_note;
37extern bool playing_melody;
38extern uint8_t note_timbre;
39
40static PWMConfig pwmCFG = {
41 .frequency = 100000, /* PWM clock frequency */
42 // 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
43 .period = 2, /* initial PWM period (in ticks) 1S (1/10kHz=0.1mS 0.1ms*10000 ticks=1S) */
44 .callback = NULL, /* no callback, the hardware directly toggles the pin */
45 .channels =
46 {
47#if AUDIO_PWM_CHANNEL == 4
48 {PWM_OUTPUT_DISABLED, NULL}, /* channel 0 -> TIMx_CH1 */
49 {PWM_OUTPUT_DISABLED, NULL}, /* channel 1 -> TIMx_CH2 */
50 {PWM_OUTPUT_DISABLED, NULL}, /* channel 2 -> TIMx_CH3 */
51 {PWM_OUTPUT_ACTIVE_HIGH, NULL} /* channel 3 -> TIMx_CH4 */
52#elif AUDIO_PWM_CHANNEL == 3
53 {PWM_OUTPUT_DISABLED, NULL},
54 {PWM_OUTPUT_DISABLED, NULL},
55 {PWM_OUTPUT_ACTIVE_HIGH, NULL}, /* TIMx_CH3 */
56 {PWM_OUTPUT_DISABLED, NULL}
57#elif AUDIO_PWM_CHANNEL == 2
58 {PWM_OUTPUT_DISABLED, NULL},
59 {PWM_OUTPUT_ACTIVE_HIGH, NULL}, /* TIMx_CH2 */
60 {PWM_OUTPUT_DISABLED, NULL},
61 {PWM_OUTPUT_DISABLED, NULL}
62#else /*fallback to CH1 */
63 {PWM_OUTPUT_ACTIVE_HIGH, NULL}, /* TIMx_CH1 */
64 {PWM_OUTPUT_DISABLED, NULL},
65 {PWM_OUTPUT_DISABLED, NULL},
66 {PWM_OUTPUT_DISABLED, NULL}
67#endif
68 },
69};
70
71static float channel_1_frequency = 0.0f;
72void channel_1_set_frequency(float freq) {
73 channel_1_frequency = freq;
74
75 if (freq <= 0.0) // a pause/rest has freq=0
76 return;
77
78 pwmcnt_t period = (pwmCFG.frequency / freq);
79 pwmChangePeriod(&AUDIO_PWM_DRIVER, period);
80 pwmEnableChannel(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1,
81 // adjust the duty-cycle so that the output is for 'note_timbre' duration HIGH
82 PWM_PERCENTAGE_TO_WIDTH(&AUDIO_PWM_DRIVER, (100 - note_timbre) * 100));
83}
84
85float channel_1_get_frequency(void) { return channel_1_frequency; }
86
87void channel_1_start(void) {
88 pwmStop(&AUDIO_PWM_DRIVER);
89 pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
90}
91
92void channel_1_stop(void) { pwmStop(&AUDIO_PWM_DRIVER); }
93
94static void gpt_callback(GPTDriver *gptp);
95GPTConfig gptCFG = {
96 /* a whole note is one beat, which is - per definition in musical_notes.h - set to 64
97 the longest note is BREAVE_DOT=128+64=192, the shortest SIXTEENTH=4
98 the tempo (which might vary!) is in bpm (beats per minute)
99 therefore: if the timer ticks away at .frequency = (60*64)Hz,
100 and the .interval counts from 64 downwards - audio_update_state is
101 called just often enough to not miss any notes
102 */
103 .frequency = 60 * 64,
104 .callback = gpt_callback,
105};
106
107void audio_driver_initialize(void) {
108 pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
109
110 // connect the AUDIO_PIN to the PWM hardware
111#if defined(USE_GPIOV1) // STM32F103C8
112 palSetLineMode(AUDIO_PIN, PAL_MODE_ALTERNATE_PUSHPULL);
113#else // GPIOv2 (or GPIOv3 for f4xx, which is the same/compatible at this command)
114 palSetLineMode(AUDIO_PIN, PAL_MODE_ALTERNATE(AUDIO_PWM_PAL_MODE));
115#endif
116
117 gptStart(&AUDIO_STATE_TIMER, &gptCFG);
118}
119
120void audio_driver_start(void) {
121 channel_1_stop();
122 channel_1_start();
123
124 if (playing_note || playing_melody) {
125 gptStartContinuous(&AUDIO_STATE_TIMER, 64);
126 }
127}
128
129void audio_driver_stop(void) {
130 channel_1_stop();
131 gptStopTimer(&AUDIO_STATE_TIMER);
132}
133
134/* a regular timer task, that checks the note to be currently played
135 * and updates the pwm to output that frequency
136 */
137static void gpt_callback(GPTDriver *gptp) {
138 float freq; // TODO: freq_alt
139
140 if (audio_update_state()) {
141 freq = audio_get_processed_frequency(0); // freq_alt would be index=1
142 channel_1_set_frequency(freq);
143 }
144}
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