1 files changed, 245 insertions, 0 deletions

diff --git a/platforms/chibios/drivers/audio_dac_basic.c b/platforms/chibios/drivers/audio_dac_basic.c
new file mode 100644
index 000000000..fac651350
--- /dev/null
+++ b/platforms/chibios/drivers/audio_dac_basic.c
@@ -0,0 +1,245 @@
+/* Copyright 2016-2020 Jack Humbert
+ * Copyright 2020 JohSchneider
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "audio.h"
+#include "ch.h"
+#include "hal.h"
+
+/*
+  Audio Driver: DAC
+
+  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
+
+  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
+  OR
+  one speaker wired to A4+A5 with the AUDIO_PIN_ALT_AS_NEGATIVE define set - see docs/feature_audio
+
+*/
+
+#if !defined(AUDIO_PIN)
+#    pragma message "Audio feature enabled, but no suitable pin selected as AUDIO_PIN - see docs/feature_audio under 'ARM (DAC basic)' for available options."
+// 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
+#    define AUDIO_PIN A5
+#endif
+// check configuration for ONE speaker, connected to both DAC pins
+#if defined(AUDIO_PIN_ALT_AS_NEGATIVE) && !defined(AUDIO_PIN_ALT)
+#    error "Audio feature: AUDIO_PIN_ALT_AS_NEGATIVE set, but no pin configured as AUDIO_PIN_ALT"
+#endif
+
+#ifndef AUDIO_PIN_ALT
+// no ALT pin defined is valid, but the c-ifs below need some value set
+#    define AUDIO_PIN_ALT -1
+#endif
+
+#if !defined(AUDIO_STATE_TIMER)
+#    define AUDIO_STATE_TIMER GPTD8
+#endif
+
+// square-wave
+static const dacsample_t dac_buffer_1[AUDIO_DAC_BUFFER_SIZE] = {
+    // First half is max, second half is 0
+    [0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1]                     = AUDIO_DAC_SAMPLE_MAX,
+    [AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = 0,
+};
+
+// square-wave
+static const dacsample_t dac_buffer_2[AUDIO_DAC_BUFFER_SIZE] = {
+    // opposite of dac_buffer above
+    [0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1]                     = 0,
+    [AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = AUDIO_DAC_SAMPLE_MAX,
+};
+
+GPTConfig gpt6cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE,
+                      .callback  = NULL,
+                      .cr2       = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event.    */
+                      .dier      = 0U};
+GPTConfig gpt7cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE,
+                      .callback  = NULL,
+                      .cr2       = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event.    */
+                      .dier      = 0U};
+
+static void gpt_audio_state_cb(GPTDriver *gptp);
+GPTConfig   gptStateUpdateCfg = {.frequency = 10,
+                               .callback  = gpt_audio_state_cb,
+                               .cr2       = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event.    */
+                               .dier      = 0U};
+
+static const DACConfig dac_conf_ch1 = {.init = AUDIO_DAC_OFF_VALUE, .datamode = DAC_DHRM_12BIT_RIGHT};
+static const DACConfig dac_conf_ch2 = {.init = AUDIO_DAC_OFF_VALUE, .datamode = DAC_DHRM_12BIT_RIGHT};
+
+/**
+ * @note The DAC_TRG(0) here selects the Timer 6 TRGO event, which is triggered
+ * on the rising edge after 3 APB1 clock cycles, causing our gpt6cfg1.frequency
+ * to be a third of what we expect.
+ *
+ * Here are all the values for DAC_TRG (TSEL in the ref manual)
+ * TIM15_TRGO 0b011
+ * TIM2_TRGO  0b100
+ * TIM3_TRGO  0b001
+ * TIM6_TRGO  0b000
+ * TIM7_TRGO  0b010
+ * EXTI9      0b110
+ * SWTRIG     0b111
+ */
+static const DACConversionGroup dac_conv_grp_ch1 = {.num_channels = 1U, .trigger = DAC_TRG(0b000)};
+static const DACConversionGroup dac_conv_grp_ch2 = {.num_channels = 1U, .trigger = DAC_TRG(0b010)};
+
+void channel_1_start(void) {
+    gptStart(&GPTD6, &gpt6cfg1);
+    gptStartContinuous(&GPTD6, 2U);
+    palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
+}
+
+void channel_1_stop(void) {
+    gptStopTimer(&GPTD6);
+    palSetPadMode(GPIOA, 4, PAL_MODE_OUTPUT_PUSHPULL);
+    palSetPad(GPIOA, 4);
+}
+
+static float channel_1_frequency = 0.0f;
+void         channel_1_set_frequency(float freq) {
+    channel_1_frequency = freq;
+
+    channel_1_stop();
+    if (freq <= 0.0)  // a pause/rest has freq=0
+        return;
+
+    gpt6cfg1.frequency = 2 * freq * AUDIO_DAC_BUFFER_SIZE;
+    channel_1_start();
+}
+float channel_1_get_frequency(void) { return channel_1_frequency; }
+
+void channel_2_start(void) {
+    gptStart(&GPTD7, &gpt7cfg1);
+    gptStartContinuous(&GPTD7, 2U);
+    palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
+}
+
+void channel_2_stop(void) {
+    gptStopTimer(&GPTD7);
+    palSetPadMode(GPIOA, 5, PAL_MODE_OUTPUT_PUSHPULL);
+    palSetPad(GPIOA, 5);
+}
+
+static float channel_2_frequency = 0.0f;
+void         channel_2_set_frequency(float freq) {
+    channel_2_frequency = freq;
+
+    channel_2_stop();
+    if (freq <= 0.0)  // a pause/rest has freq=0
+        return;
+
+    gpt7cfg1.frequency = 2 * freq * AUDIO_DAC_BUFFER_SIZE;
+    channel_2_start();
+}
+float channel_2_get_frequency(void) { return channel_2_frequency; }
+
+static void gpt_audio_state_cb(GPTDriver *gptp) {
+    if (audio_update_state()) {
+#if defined(AUDIO_PIN_ALT_AS_NEGATIVE)
+        // one piezo/speaker connected to both audio pins, the generated square-waves are inverted
+        channel_1_set_frequency(audio_get_processed_frequency(0));
+        channel_2_set_frequency(audio_get_processed_frequency(0));
+
+#else  // two separate audio outputs/speakers
+       // primary speaker on A4, optional secondary on A5
+        if (AUDIO_PIN == A4) {
+            channel_1_set_frequency(audio_get_processed_frequency(0));
+            if (AUDIO_PIN_ALT == A5) {
+                if (audio_get_number_of_active_tones() > 1) {
+                    channel_2_set_frequency(audio_get_processed_frequency(1));
+                } else {
+                    channel_2_stop();
+                }
+            }
+        }
+
+        // primary speaker on A5, optional secondary on A4
+        if (AUDIO_PIN == A5) {
+            channel_2_set_frequency(audio_get_processed_frequency(0));
+            if (AUDIO_PIN_ALT == A4) {
+                if (audio_get_number_of_active_tones() > 1) {
+                    channel_1_set_frequency(audio_get_processed_frequency(1));
+                } else {
+                    channel_1_stop();
+                }
+            }
+        }
+#endif
+    }
+}
+
+void audio_driver_initialize() {
+    if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
+        palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
+        dacStart(&DACD1, &dac_conf_ch1);
+
+        // initial setup of the dac-triggering timer is still required, even
+        // though it gets reconfigured and restarted later on
+        gptStart(&GPTD6, &gpt6cfg1);
+    }
+
+    if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
+        palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
+        dacStart(&DACD2, &dac_conf_ch2);
+
+        gptStart(&GPTD7, &gpt7cfg1);
+    }
+
+    /* enable the output buffer, to directly drive external loads with no additional circuitry
+     *
+     * see: AN4566 Application note: Extending the DAC performance of STM32 microcontrollers
+     * Note: Buffer-Off bit -> has to be set 0 to enable the output buffer
+     * Note: enabling the output buffer imparts an additional dc-offset of a couple mV
+     *
+     * this is done here, reaching directly into the stm32 registers since chibios has not implemented BOFF handling yet
+     * (see: chibios/os/hal/ports/STM32/todo.txt '- BOFF handling in DACv1.'
+     */
+    DACD1.params->dac->CR &= ~DAC_CR_BOFF1;
+    DACD2.params->dac->CR &= ~DAC_CR_BOFF2;
+
+    // start state-updater
+    gptStart(&AUDIO_STATE_TIMER, &gptStateUpdateCfg);
+}
+
+void audio_driver_stop(void) {
+    if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
+        gptStopTimer(&GPTD6);
+
+        // stop the ongoing conversion and put the output in a known state
+        dacStopConversion(&DACD1);
+        dacPutChannelX(&DACD1, 0, AUDIO_DAC_OFF_VALUE);
+    }
+
+    if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
+        gptStopTimer(&GPTD7);
+
+        dacStopConversion(&DACD2);
+        dacPutChannelX(&DACD2, 0, AUDIO_DAC_OFF_VALUE);
+    }
+    gptStopTimer(&AUDIO_STATE_TIMER);
+}
+
+void audio_driver_start(void) {
+    if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
+        dacStartConversion(&DACD1, &dac_conv_grp_ch1, (dacsample_t *)dac_buffer_1, AUDIO_DAC_BUFFER_SIZE);
+    }
+    if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
+        dacStartConversion(&DACD2, &dac_conv_grp_ch2, (dacsample_t *)dac_buffer_2, AUDIO_DAC_BUFFER_SIZE);
+    }
+    gptStartContinuous(&AUDIO_STATE_TIMER, 2U);
+}