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-rw-r--r--quantum/audio/driver_chibios_dac_basic.c245
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diff --git a/quantum/audio/driver_chibios_dac_basic.c b/quantum/audio/driver_chibios_dac_basic.c
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1/* Copyright 2016-2020 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#include "audio.h"
19#include "ch.h"
20#include "hal.h"
21
22/*
23 Audio Driver: DAC
24
25 which utilizes both channels of the DAC unit many STM32 are equipped with to output a modulated square-wave, from precomputed samples stored in a buffer, which is passed to the hardware through DMA
26
27 this driver can either be used to drive to separate speakers, wired to A4+Gnd and A5+Gnd, which allows two tones to be played simultaneously
28 OR
29 one speaker wired to A4+A5 with the AUDIO_PIN_ALT_AS_NEGATIVE define set - see docs/feature_audio
30
31*/
32
33#if !defined(AUDIO_PIN)
34# pragma message "Audio feature enabled, but no suitable pin selected as AUDIO_PIN - see docs/feature_audio under 'ARM (DAC basic)' for available options."
35// TODO: make this an 'error' instead; go through a breaking change, and add AUDIO_PIN A5 to all keyboards currently using AUDIO on STM32 based boards? - for now: set the define here
36# define AUDIO_PIN A5
37#endif
38// check configuration for ONE speaker, connected to both DAC pins
39#if defined(AUDIO_PIN_ALT_AS_NEGATIVE) && !defined(AUDIO_PIN_ALT)
40# error "Audio feature: AUDIO_PIN_ALT_AS_NEGATIVE set, but no pin configured as AUDIO_PIN_ALT"
41#endif
42
43#ifndef AUDIO_PIN_ALT
44// no ALT pin defined is valid, but the c-ifs below need some value set
45# define AUDIO_PIN_ALT -1
46#endif
47
48#if !defined(AUDIO_STATE_TIMER)
49# define AUDIO_STATE_TIMER GPTD8
50#endif
51
52// square-wave
53static const dacsample_t dac_buffer_1[AUDIO_DAC_BUFFER_SIZE] = {
54 // First half is max, second half is 0
55 [0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1] = AUDIO_DAC_SAMPLE_MAX,
56 [AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = 0,
57};
58
59// square-wave
60static const dacsample_t dac_buffer_2[AUDIO_DAC_BUFFER_SIZE] = {
61 // opposite of dac_buffer above
62 [0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1] = 0,
63 [AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = AUDIO_DAC_SAMPLE_MAX,
64};
65
66GPTConfig gpt6cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE,
67 .callback = NULL,
68 .cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */
69 .dier = 0U};
70GPTConfig gpt7cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE,
71 .callback = NULL,
72 .cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */
73 .dier = 0U};
74
75static void gpt_audio_state_cb(GPTDriver *gptp);
76GPTConfig gptStateUpdateCfg = {.frequency = 10,
77 .callback = gpt_audio_state_cb,
78 .cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */
79 .dier = 0U};
80
81static const DACConfig dac_conf_ch1 = {.init = AUDIO_DAC_OFF_VALUE, .datamode = DAC_DHRM_12BIT_RIGHT};
82static const DACConfig dac_conf_ch2 = {.init = AUDIO_DAC_OFF_VALUE, .datamode = DAC_DHRM_12BIT_RIGHT};
83
84/**
85 * @note The DAC_TRG(0) here selects the Timer 6 TRGO event, which is triggered
86 * on the rising edge after 3 APB1 clock cycles, causing our gpt6cfg1.frequency
87 * to be a third of what we expect.
88 *
89 * Here are all the values for DAC_TRG (TSEL in the ref manual)
90 * TIM15_TRGO 0b011
91 * TIM2_TRGO 0b100
92 * TIM3_TRGO 0b001
93 * TIM6_TRGO 0b000
94 * TIM7_TRGO 0b010
95 * EXTI9 0b110
96 * SWTRIG 0b111
97 */
98static const DACConversionGroup dac_conv_grp_ch1 = {.num_channels = 1U, .trigger = DAC_TRG(0b000)};
99static const DACConversionGroup dac_conv_grp_ch2 = {.num_channels = 1U, .trigger = DAC_TRG(0b010)};
100
101void channel_1_start(void) {
102 gptStart(&GPTD6, &gpt6cfg1);
103 gptStartContinuous(&GPTD6, 2U);
104 palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
105}
106
107void channel_1_stop(void) {
108 gptStopTimer(&GPTD6);
109 palSetPadMode(GPIOA, 4, PAL_MODE_OUTPUT_PUSHPULL);
110 palSetPad(GPIOA, 4);
111}
112
113static float channel_1_frequency = 0.0f;
114void channel_1_set_frequency(float freq) {
115 channel_1_frequency = freq;
116
117 channel_1_stop();
118 if (freq <= 0.0) // a pause/rest has freq=0
119 return;
120
121 gpt6cfg1.frequency = 2 * freq * AUDIO_DAC_BUFFER_SIZE;
122 channel_1_start();
123}
124float channel_1_get_frequency(void) { return channel_1_frequency; }
125
126void channel_2_start(void) {
127 gptStart(&GPTD7, &gpt7cfg1);
128 gptStartContinuous(&GPTD7, 2U);
129 palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
130}
131
132void channel_2_stop(void) {
133 gptStopTimer(&GPTD7);
134 palSetPadMode(GPIOA, 5, PAL_MODE_OUTPUT_PUSHPULL);
135 palSetPad(GPIOA, 5);
136}
137
138static float channel_2_frequency = 0.0f;
139void channel_2_set_frequency(float freq) {
140 channel_2_frequency = freq;
141
142 channel_2_stop();
143 if (freq <= 0.0) // a pause/rest has freq=0
144 return;
145
146 gpt7cfg1.frequency = 2 * freq * AUDIO_DAC_BUFFER_SIZE;
147 channel_2_start();
148}
149float channel_2_get_frequency(void) { return channel_2_frequency; }
150
151static void gpt_audio_state_cb(GPTDriver *gptp) {
152 if (audio_update_state()) {
153#if defined(AUDIO_PIN_ALT_AS_NEGATIVE)
154 // one piezo/speaker connected to both audio pins, the generated square-waves are inverted
155 channel_1_set_frequency(audio_get_processed_frequency(0));
156 channel_2_set_frequency(audio_get_processed_frequency(0));
157
158#else // two separate audio outputs/speakers
159 // primary speaker on A4, optional secondary on A5
160 if (AUDIO_PIN == A4) {
161 channel_1_set_frequency(audio_get_processed_frequency(0));
162 if (AUDIO_PIN_ALT == A5) {
163 if (audio_get_number_of_active_tones() > 1) {
164 channel_2_set_frequency(audio_get_processed_frequency(1));
165 } else {
166 channel_2_stop();
167 }
168 }
169 }
170
171 // primary speaker on A5, optional secondary on A4
172 if (AUDIO_PIN == A5) {
173 channel_2_set_frequency(audio_get_processed_frequency(0));
174 if (AUDIO_PIN_ALT == A4) {
175 if (audio_get_number_of_active_tones() > 1) {
176 channel_1_set_frequency(audio_get_processed_frequency(1));
177 } else {
178 channel_1_stop();
179 }
180 }
181 }
182#endif
183 }
184}
185
186void audio_driver_initialize() {
187 if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
188 palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
189 dacStart(&DACD1, &dac_conf_ch1);
190
191 // initial setup of the dac-triggering timer is still required, even
192 // though it gets reconfigured and restarted later on
193 gptStart(&GPTD6, &gpt6cfg1);
194 }
195
196 if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
197 palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
198 dacStart(&DACD2, &dac_conf_ch2);
199
200 gptStart(&GPTD7, &gpt7cfg1);
201 }
202
203 /* enable the output buffer, to directly drive external loads with no additional circuitry
204 *
205 * see: AN4566 Application note: Extending the DAC performance of STM32 microcontrollers
206 * Note: Buffer-Off bit -> has to be set 0 to enable the output buffer
207 * Note: enabling the output buffer imparts an additional dc-offset of a couple mV
208 *
209 * this is done here, reaching directly into the stm32 registers since chibios has not implemented BOFF handling yet
210 * (see: chibios/os/hal/ports/STM32/todo.txt '- BOFF handling in DACv1.'
211 */
212 DACD1.params->dac->CR &= ~DAC_CR_BOFF1;
213 DACD2.params->dac->CR &= ~DAC_CR_BOFF2;
214
215 // start state-updater
216 gptStart(&AUDIO_STATE_TIMER, &gptStateUpdateCfg);
217}
218
219void audio_driver_stop(void) {
220 if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
221 gptStopTimer(&GPTD6);
222
223 // stop the ongoing conversion and put the output in a known state
224 dacStopConversion(&DACD1);
225 dacPutChannelX(&DACD1, 0, AUDIO_DAC_OFF_VALUE);
226 }
227
228 if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
229 gptStopTimer(&GPTD7);
230
231 dacStopConversion(&DACD2);
232 dacPutChannelX(&DACD2, 0, AUDIO_DAC_OFF_VALUE);
233 }
234 gptStopTimer(&AUDIO_STATE_TIMER);
235}
236
237void audio_driver_start(void) {
238 if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
239 dacStartConversion(&DACD1, &dac_conv_grp_ch1, (dacsample_t *)dac_buffer_1, AUDIO_DAC_BUFFER_SIZE);
240 }
241 if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
242 dacStartConversion(&DACD2, &dac_conv_grp_ch2, (dacsample_t *)dac_buffer_2, AUDIO_DAC_BUFFER_SIZE);
243 }
244 gptStartContinuous(&AUDIO_STATE_TIMER, 2U);
245}
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