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diff --git a/platforms/chibios/drivers/audio_dac_additive.c b/platforms/chibios/drivers/audio_dac_additive.c
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1/* Copyright 2016-2019 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 the dac unit many STM32 are equipped with, to output a modulated waveform from samples stored in the dac_buffer_* array who are passed to the hardware through DMA
26
27 it is also possible to have a custom sample-LUT by implementing/overriding 'dac_value_generate'
28
29 this driver allows for multiple simultaneous tones to be played through one single channel by doing additive wave-synthesis
30*/
31
32#if !defined(AUDIO_PIN)
33# error "Audio feature enabled, but no suitable pin selected as AUDIO_PIN - see docs/feature_audio under 'ARM (DAC additive)' for available options."
34#endif
35#if defined(AUDIO_PIN_ALT) && !defined(AUDIO_PIN_ALT_AS_NEGATIVE)
36# pragma message "Audio feature: AUDIO_PIN_ALT set, but not AUDIO_PIN_ALT_AS_NEGATIVE - pin will be left unused; audio might still work though."
37#endif
38
39#if !defined(AUDIO_PIN_ALT)
40// no ALT pin defined is valid, but the c-ifs below need some value set
41# define AUDIO_PIN_ALT PAL_NOLINE
42#endif
43
44#if !defined(AUDIO_DAC_SAMPLE_WAVEFORM_SINE) && !defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE) && !defined(AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE) && !defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID)
45# define AUDIO_DAC_SAMPLE_WAVEFORM_SINE
46#endif
47
48#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_SINE
49/* one full sine wave over [0,2*pi], but shifted up one amplitude and left pi/4; for the samples to start at 0
50 */
51static const dacsample_t dac_buffer_sine[AUDIO_DAC_BUFFER_SIZE] = {
52 // 256 values, max 4095
53 0x0, 0x1, 0x2, 0x6, 0xa, 0xf, 0x16, 0x1e, 0x27, 0x32, 0x3d, 0x4a, 0x58, 0x67, 0x78, 0x89, 0x9c, 0xb0, 0xc5, 0xdb, 0xf2, 0x10a, 0x123, 0x13e, 0x159, 0x175, 0x193, 0x1b1, 0x1d1, 0x1f1, 0x212, 0x235, 0x258, 0x27c, 0x2a0, 0x2c6, 0x2ed, 0x314, 0x33c, 0x365, 0x38e, 0x3b8, 0x3e3, 0x40e, 0x43a, 0x467, 0x494, 0x4c2, 0x4f0, 0x51f, 0x54e, 0x57d, 0x5ad, 0x5dd, 0x60e, 0x63f, 0x670, 0x6a1, 0x6d3, 0x705, 0x737, 0x769, 0x79b, 0x7cd, 0x800, 0x832, 0x864, 0x896, 0x8c8, 0x8fa, 0x92c, 0x95e, 0x98f, 0x9c0, 0x9f1, 0xa22, 0xa52, 0xa82, 0xab1, 0xae0, 0xb0f, 0xb3d, 0xb6b, 0xb98, 0xbc5, 0xbf1, 0xc1c, 0xc47, 0xc71, 0xc9a, 0xcc3, 0xceb, 0xd12, 0xd39, 0xd5f, 0xd83, 0xda7, 0xdca, 0xded, 0xe0e, 0xe2e, 0xe4e, 0xe6c, 0xe8a, 0xea6, 0xec1, 0xedc, 0xef5, 0xf0d, 0xf24, 0xf3a, 0xf4f, 0xf63, 0xf76, 0xf87, 0xf98, 0xfa7, 0xfb5, 0xfc2, 0xfcd, 0xfd8, 0xfe1, 0xfe9, 0xff0, 0xff5, 0xff9, 0xffd, 0xffe,
54 0xfff, 0xffe, 0xffd, 0xff9, 0xff5, 0xff0, 0xfe9, 0xfe1, 0xfd8, 0xfcd, 0xfc2, 0xfb5, 0xfa7, 0xf98, 0xf87, 0xf76, 0xf63, 0xf4f, 0xf3a, 0xf24, 0xf0d, 0xef5, 0xedc, 0xec1, 0xea6, 0xe8a, 0xe6c, 0xe4e, 0xe2e, 0xe0e, 0xded, 0xdca, 0xda7, 0xd83, 0xd5f, 0xd39, 0xd12, 0xceb, 0xcc3, 0xc9a, 0xc71, 0xc47, 0xc1c, 0xbf1, 0xbc5, 0xb98, 0xb6b, 0xb3d, 0xb0f, 0xae0, 0xab1, 0xa82, 0xa52, 0xa22, 0x9f1, 0x9c0, 0x98f, 0x95e, 0x92c, 0x8fa, 0x8c8, 0x896, 0x864, 0x832, 0x800, 0x7cd, 0x79b, 0x769, 0x737, 0x705, 0x6d3, 0x6a1, 0x670, 0x63f, 0x60e, 0x5dd, 0x5ad, 0x57d, 0x54e, 0x51f, 0x4f0, 0x4c2, 0x494, 0x467, 0x43a, 0x40e, 0x3e3, 0x3b8, 0x38e, 0x365, 0x33c, 0x314, 0x2ed, 0x2c6, 0x2a0, 0x27c, 0x258, 0x235, 0x212, 0x1f1, 0x1d1, 0x1b1, 0x193, 0x175, 0x159, 0x13e, 0x123, 0x10a, 0xf2, 0xdb, 0xc5, 0xb0, 0x9c, 0x89, 0x78, 0x67, 0x58, 0x4a, 0x3d, 0x32, 0x27, 0x1e, 0x16, 0xf, 0xa, 0x6, 0x2, 0x1};
55#endif // AUDIO_DAC_SAMPLE_WAVEFORM_SINE
56#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE
57static const dacsample_t dac_buffer_triangle[AUDIO_DAC_BUFFER_SIZE] = {
58 // 256 values, max 4095
59 0x0, 0x20, 0x40, 0x60, 0x80, 0xa0, 0xc0, 0xe0, 0x100, 0x120, 0x140, 0x160, 0x180, 0x1a0, 0x1c0, 0x1e0, 0x200, 0x220, 0x240, 0x260, 0x280, 0x2a0, 0x2c0, 0x2e0, 0x300, 0x320, 0x340, 0x360, 0x380, 0x3a0, 0x3c0, 0x3e0, 0x400, 0x420, 0x440, 0x460, 0x480, 0x4a0, 0x4c0, 0x4e0, 0x500, 0x520, 0x540, 0x560, 0x580, 0x5a0, 0x5c0, 0x5e0, 0x600, 0x620, 0x640, 0x660, 0x680, 0x6a0, 0x6c0, 0x6e0, 0x700, 0x720, 0x740, 0x760, 0x780, 0x7a0, 0x7c0, 0x7e0, 0x800, 0x81f, 0x83f, 0x85f, 0x87f, 0x89f, 0x8bf, 0x8df, 0x8ff, 0x91f, 0x93f, 0x95f, 0x97f, 0x99f, 0x9bf, 0x9df, 0x9ff, 0xa1f, 0xa3f, 0xa5f, 0xa7f, 0xa9f, 0xabf, 0xadf, 0xaff, 0xb1f, 0xb3f, 0xb5f, 0xb7f, 0xb9f, 0xbbf, 0xbdf, 0xbff, 0xc1f, 0xc3f, 0xc5f, 0xc7f, 0xc9f, 0xcbf, 0xcdf, 0xcff, 0xd1f, 0xd3f, 0xd5f, 0xd7f, 0xd9f, 0xdbf, 0xddf, 0xdff, 0xe1f, 0xe3f, 0xe5f, 0xe7f, 0xe9f, 0xebf, 0xedf, 0xeff, 0xf1f, 0xf3f, 0xf5f, 0xf7f, 0xf9f, 0xfbf, 0xfdf,
60 0xfff, 0xfdf, 0xfbf, 0xf9f, 0xf7f, 0xf5f, 0xf3f, 0xf1f, 0xeff, 0xedf, 0xebf, 0xe9f, 0xe7f, 0xe5f, 0xe3f, 0xe1f, 0xdff, 0xddf, 0xdbf, 0xd9f, 0xd7f, 0xd5f, 0xd3f, 0xd1f, 0xcff, 0xcdf, 0xcbf, 0xc9f, 0xc7f, 0xc5f, 0xc3f, 0xc1f, 0xbff, 0xbdf, 0xbbf, 0xb9f, 0xb7f, 0xb5f, 0xb3f, 0xb1f, 0xaff, 0xadf, 0xabf, 0xa9f, 0xa7f, 0xa5f, 0xa3f, 0xa1f, 0x9ff, 0x9df, 0x9bf, 0x99f, 0x97f, 0x95f, 0x93f, 0x91f, 0x8ff, 0x8df, 0x8bf, 0x89f, 0x87f, 0x85f, 0x83f, 0x81f, 0x800, 0x7e0, 0x7c0, 0x7a0, 0x780, 0x760, 0x740, 0x720, 0x700, 0x6e0, 0x6c0, 0x6a0, 0x680, 0x660, 0x640, 0x620, 0x600, 0x5e0, 0x5c0, 0x5a0, 0x580, 0x560, 0x540, 0x520, 0x500, 0x4e0, 0x4c0, 0x4a0, 0x480, 0x460, 0x440, 0x420, 0x400, 0x3e0, 0x3c0, 0x3a0, 0x380, 0x360, 0x340, 0x320, 0x300, 0x2e0, 0x2c0, 0x2a0, 0x280, 0x260, 0x240, 0x220, 0x200, 0x1e0, 0x1c0, 0x1a0, 0x180, 0x160, 0x140, 0x120, 0x100, 0xe0, 0xc0, 0xa0, 0x80, 0x60, 0x40, 0x20};
61#endif // AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE
62#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE
63static const dacsample_t dac_buffer_square[AUDIO_DAC_BUFFER_SIZE] = {
64 [0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1] = 0, // first and
65 [AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = AUDIO_DAC_SAMPLE_MAX, // second half
66};
67#endif // AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE
68/*
69// four steps: 0, 1/3, 2/3 and 1
70static const dacsample_t dac_buffer_staircase[AUDIO_DAC_BUFFER_SIZE] = {
71 [0 ... AUDIO_DAC_BUFFER_SIZE/3 -1 ] = 0,
72 [AUDIO_DAC_BUFFER_SIZE / 4 ... AUDIO_DAC_BUFFER_SIZE / 2 -1 ] = AUDIO_DAC_SAMPLE_MAX / 3,
73 [AUDIO_DAC_BUFFER_SIZE / 2 ... 3 * AUDIO_DAC_BUFFER_SIZE / 4 -1 ] = 2 * AUDIO_DAC_SAMPLE_MAX / 3,
74 [3 * AUDIO_DAC_BUFFER_SIZE / 4 ... AUDIO_DAC_BUFFER_SIZE -1 ] = AUDIO_DAC_SAMPLE_MAX,
75}
76*/
77#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID
78static const dacsample_t dac_buffer_trapezoid[AUDIO_DAC_BUFFER_SIZE] = {0x0, 0x1f, 0x7f, 0xdf, 0x13f, 0x19f, 0x1ff, 0x25f, 0x2bf, 0x31f, 0x37f, 0x3df, 0x43f, 0x49f, 0x4ff, 0x55f, 0x5bf, 0x61f, 0x67f, 0x6df, 0x73f, 0x79f, 0x7ff, 0x85f, 0x8bf, 0x91f, 0x97f, 0x9df, 0xa3f, 0xa9f, 0xaff, 0xb5f, 0xbbf, 0xc1f, 0xc7f, 0xcdf, 0xd3f, 0xd9f, 0xdff, 0xe5f, 0xebf, 0xf1f, 0xf7f, 0xfdf, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff,
79 0xfff, 0xfdf, 0xf7f, 0xf1f, 0xebf, 0xe5f, 0xdff, 0xd9f, 0xd3f, 0xcdf, 0xc7f, 0xc1f, 0xbbf, 0xb5f, 0xaff, 0xa9f, 0xa3f, 0x9df, 0x97f, 0x91f, 0x8bf, 0x85f, 0x7ff, 0x79f, 0x73f, 0x6df, 0x67f, 0x61f, 0x5bf, 0x55f, 0x4ff, 0x49f, 0x43f, 0x3df, 0x37f, 0x31f, 0x2bf, 0x25f, 0x1ff, 0x19f, 0x13f, 0xdf, 0x7f, 0x1f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0};
80#endif // AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID
81
82static dacsample_t dac_buffer_empty[AUDIO_DAC_BUFFER_SIZE] = {AUDIO_DAC_OFF_VALUE};
83
84/* keep track of the sample position for for each frequency */
85static float dac_if[AUDIO_MAX_SIMULTANEOUS_TONES] = {0.0};
86
87static float active_tones_snapshot[AUDIO_MAX_SIMULTANEOUS_TONES] = {0, 0};
88static uint8_t active_tones_snapshot_length = 0;
89
90typedef enum {
91 OUTPUT_SHOULD_START,
92 OUTPUT_RUN_NORMALLY,
93 // path 1: wait for zero, then change/update active tones
94 OUTPUT_TONES_CHANGED,
95 OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE,
96 // path 2: hardware should stop, wait for zero then turn output off = stop the timer
97 OUTPUT_SHOULD_STOP,
98 OUTPUT_REACHED_ZERO_BEFORE_OFF,
99 OUTPUT_OFF,
100 OUTPUT_OFF_1,
101 OUTPUT_OFF_2, // trailing off: giving the DAC two more conversion cycles until the AUDIO_DAC_OFF_VALUE reaches the output, then turn the timer off, which leaves the output at that level
102 number_of_output_states
103} output_states_t;
104output_states_t state = OUTPUT_OFF_2;
105
106/**
107 * Generation of the waveform being passed to the callback. Declared weak so users
108 * can override it with their own wave-forms/noises.
109 */
110__attribute__((weak)) uint16_t dac_value_generate(void) {
111 // DAC is running/asking for values but snapshot length is zero -> must be playing a pause
112 if (active_tones_snapshot_length == 0) {
113 return AUDIO_DAC_OFF_VALUE;
114 }
115
116 /* doing additive wave synthesis over all currently playing tones = adding up
117 * sine-wave-samples for each frequency, scaled by the number of active tones
118 */
119 uint16_t value = 0;
120 float frequency = 0.0f;
121
122 for (uint8_t i = 0; i < active_tones_snapshot_length; i++) {
123 /* Note: a user implementation does not have to rely on the active_tones_snapshot, but
124 * could directly query the active frequencies through audio_get_processed_frequency */
125 frequency = active_tones_snapshot[i];
126
127 dac_if[i] = dac_if[i] + ((frequency * AUDIO_DAC_BUFFER_SIZE) / AUDIO_DAC_SAMPLE_RATE) * 2 / 3;
128 /*Note: the 2/3 are necessary to get the correct frequencies on the
129 * DAC output (as measured with an oscilloscope), since the gpt
130 * timer runs with 3*AUDIO_DAC_SAMPLE_RATE; and the DAC callback
131 * is called twice per conversion.*/
132
133 dac_if[i] = fmod(dac_if[i], AUDIO_DAC_BUFFER_SIZE);
134
135 // Wavetable generation/lookup
136 uint16_t dac_i = (uint16_t)dac_if[i];
137
138#if defined(AUDIO_DAC_SAMPLE_WAVEFORM_SINE)
139 value += dac_buffer_sine[dac_i] / active_tones_snapshot_length;
140#elif defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE)
141 value += dac_buffer_triangle[dac_i] / active_tones_snapshot_length;
142#elif defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID)
143 value += dac_buffer_trapezoid[dac_i] / active_tones_snapshot_length;
144#elif defined(AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE)
145 value += dac_buffer_square[dac_i] / active_tones_snapshot_length;
146#endif
147 /*
148 // SINE
149 value += dac_buffer_sine[dac_i] / active_tones_snapshot_length / 3;
150 // TRIANGLE
151 value += dac_buffer_triangle[dac_i] / active_tones_snapshot_length / 3;
152 // SQUARE
153 value += dac_buffer_square[dac_i] / active_tones_snapshot_length / 3;
154 //NOTE: combination of these three wave-forms is more exemplary - and doesn't sound particularly good :-P
155 */
156
157 // STAIRS (mostly usefully as test-pattern)
158 // value_avg = dac_buffer_staircase[dac_i] / active_tones_snapshot_length;
159 }
160
161 return value;
162}
163
164/**
165 * DAC streaming callback. Does all of the main computing for playing songs.
166 *
167 * Note: chibios calls this CB twice: during the 'half buffer event', and the 'full buffer event'.
168 */
169static void dac_end(DACDriver *dacp) {
170 dacsample_t *sample_p = (dacp)->samples;
171
172 // work on the other half of the buffer
173 if (dacIsBufferComplete(dacp)) {
174 sample_p += AUDIO_DAC_BUFFER_SIZE / 2; // 'half_index'
175 }
176
177 for (uint8_t s = 0; s < AUDIO_DAC_BUFFER_SIZE / 2; s++) {
178 if (OUTPUT_OFF <= state) {
179 sample_p[s] = AUDIO_DAC_OFF_VALUE;
180 continue;
181 } else {
182 sample_p[s] = dac_value_generate();
183 }
184
185 /* zero crossing (or approach, whereas zero == DAC_OFF_VALUE, which can be configured to anything from 0 to DAC_SAMPLE_MAX)
186 * ============================*=*========================== AUDIO_DAC_SAMPLE_MAX
187 * * *
188 * * *
189 * ---------------------------------------------------------
190 * * * } AUDIO_DAC_SAMPLE_MAX/100
191 * --------------------------------------------------------- AUDIO_DAC_OFF_VALUE
192 * * * } AUDIO_DAC_SAMPLE_MAX/100
193 * ---------------------------------------------------------
194 * *
195 * * *
196 * * *
197 * =====*=*================================================= 0x0
198 */
199 if (((sample_p[s] + (AUDIO_DAC_SAMPLE_MAX / 100)) > AUDIO_DAC_OFF_VALUE) && // value approaches from below
200 (sample_p[s] < (AUDIO_DAC_OFF_VALUE + (AUDIO_DAC_SAMPLE_MAX / 100))) // or above
201 ) {
202 if ((OUTPUT_SHOULD_START == state) && (active_tones_snapshot_length > 0)) {
203 state = OUTPUT_RUN_NORMALLY;
204 } else if (OUTPUT_TONES_CHANGED == state) {
205 state = OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE;
206 } else if (OUTPUT_SHOULD_STOP == state) {
207 state = OUTPUT_REACHED_ZERO_BEFORE_OFF;
208 }
209 }
210
211 // still 'ramping up', reset the output to OFF_VALUE until the generated values reach that value, to do a smooth handover
212 if (OUTPUT_SHOULD_START == state) {
213 sample_p[s] = AUDIO_DAC_OFF_VALUE;
214 }
215
216 if ((OUTPUT_SHOULD_START == state) || (OUTPUT_REACHED_ZERO_BEFORE_OFF == state) || (OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE == state)) {
217 uint8_t active_tones = MIN(AUDIO_MAX_SIMULTANEOUS_TONES, audio_get_number_of_active_tones());
218 active_tones_snapshot_length = 0;
219 // update the snapshot - once, and only on occasion that something changed;
220 // -> saves cpu cycles (?)
221 for (uint8_t i = 0; i < active_tones; i++) {
222 float freq = audio_get_processed_frequency(i);
223 if (freq > 0) { // disregard 'rest' notes, with valid frequency 0.0f; which would only lower the resulting waveform volume during the additive synthesis step
224 active_tones_snapshot[active_tones_snapshot_length++] = freq;
225 }
226 }
227
228 if ((0 == active_tones_snapshot_length) && (OUTPUT_REACHED_ZERO_BEFORE_OFF == state)) {
229 state = OUTPUT_OFF;
230 }
231 if (OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE == state) {
232 state = OUTPUT_RUN_NORMALLY;
233 }
234 }
235 }
236
237 // update audio internal state (note position, current_note, ...)
238 if (audio_update_state()) {
239 if (OUTPUT_SHOULD_STOP != state) {
240 state = OUTPUT_TONES_CHANGED;
241 }
242 }
243
244 if (OUTPUT_OFF <= state) {
245 if (OUTPUT_OFF_2 == state) {
246 // stopping timer6 = stopping the DAC at whatever value it is currently pushing to the output = AUDIO_DAC_OFF_VALUE
247 gptStopTimer(&GPTD6);
248 } else {
249 state++;
250 }
251 }
252}
253
254static void dac_error(DACDriver *dacp, dacerror_t err) {
255 (void)dacp;
256 (void)err;
257
258 chSysHalt("DAC failure. halp");
259}
260
261static const GPTConfig gpt6cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE * 3,
262 .callback = NULL,
263 .cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */
264 .dier = 0U};
265
266static const DACConfig dac_conf = {.init = AUDIO_DAC_OFF_VALUE, .datamode = DAC_DHRM_12BIT_RIGHT};
267
268/**
269 * @note The DAC_TRG(0) here selects the Timer 6 TRGO event, which is triggered
270 * on the rising edge after 3 APB1 clock cycles, causing our gpt6cfg1.frequency
271 * to be a third of what we expect.
272 *
273 * Here are all the values for DAC_TRG (TSEL in the ref manual)
274 * TIM15_TRGO 0b011
275 * TIM2_TRGO 0b100
276 * TIM3_TRGO 0b001
277 * TIM6_TRGO 0b000
278 * TIM7_TRGO 0b010
279 * EXTI9 0b110
280 * SWTRIG 0b111
281 */
282static const DACConversionGroup dac_conv_cfg = {.num_channels = 1U, .end_cb = dac_end, .error_cb = dac_error, .trigger = DAC_TRG(0b000)};
283
284void audio_driver_initialize() {
285 if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
286 palSetLineMode(A4, PAL_MODE_INPUT_ANALOG);
287 dacStart(&DACD1, &dac_conf);
288 }
289 if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
290 palSetLineMode(A5, PAL_MODE_INPUT_ANALOG);
291 dacStart(&DACD2, &dac_conf);
292 }
293
294 /* enable the output buffer, to directly drive external loads with no additional circuitry
295 *
296 * see: AN4566 Application note: Extending the DAC performance of STM32 microcontrollers
297 * Note: Buffer-Off bit -> has to be set 0 to enable the output buffer
298 * Note: enabling the output buffer imparts an additional dc-offset of a couple mV
299 *
300 * this is done here, reaching directly into the stm32 registers since chibios has not implemented BOFF handling yet
301 * (see: chibios/os/hal/ports/STM32/todo.txt '- BOFF handling in DACv1.'
302 */
303 DACD1.params->dac->CR &= ~DAC_CR_BOFF1;
304 DACD2.params->dac->CR &= ~DAC_CR_BOFF2;
305
306 if (AUDIO_PIN == A4) {
307 dacStartConversion(&DACD1, &dac_conv_cfg, dac_buffer_empty, AUDIO_DAC_BUFFER_SIZE);
308 } else if (AUDIO_PIN == A5) {
309 dacStartConversion(&DACD2, &dac_conv_cfg, dac_buffer_empty, AUDIO_DAC_BUFFER_SIZE);
310 }
311
312 // no inverted/out-of-phase waveform (yet?), only pulling AUDIO_PIN_ALT to AUDIO_DAC_OFF_VALUE
313#if defined(AUDIO_PIN_ALT_AS_NEGATIVE)
314 if (AUDIO_PIN_ALT == A4) {
315 dacPutChannelX(&DACD1, 0, AUDIO_DAC_OFF_VALUE);
316 } else if (AUDIO_PIN_ALT == A5) {
317 dacPutChannelX(&DACD2, 0, AUDIO_DAC_OFF_VALUE);
318 }
319#endif
320
321 gptStart(&GPTD6, &gpt6cfg1);
322}
323
324void audio_driver_stop(void) { state = OUTPUT_SHOULD_STOP; }
325
326void audio_driver_start(void) {
327 gptStartContinuous(&GPTD6, 2U);
328
329 for (uint8_t i = 0; i < AUDIO_MAX_SIMULTANEOUS_TONES; i++) {
330 dac_if[i] = 0.0f;
331 active_tones_snapshot[i] = 0.0f;
332 }
333 active_tones_snapshot_length = 0;
334 state = OUTPUT_SHOULD_START;
335}
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