Add PWM based audio playback

See
https://learn.adafruit.com/circuitpython-essentials/circuitpython-audio-out
to get started.

Fixes #4037

1 files changed, 91 insertions, 0 deletions

diff --git a/ports/raspberrypi/audio_dma.h b/ports/raspberrypi/audio_dma.h
new file mode 100644
index 000000000..1f739ff73
--- /dev/null
+++ b/ports/raspberrypi/audio_dma.h
@@ -0,0 +1,91 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_RASPBERRYPI_AUDIO_DMA_OUT_H
+#define MICROPY_INCLUDED_RASPBERRYPI_AUDIO_DMA_OUT_H
+
+#include "py/obj.h"
+#include "supervisor/background_callback.h"
+
+#include "src/rp2_common/hardware_dma/include/hardware/dma.h"
+
+typedef struct {
+    mp_obj_t sample;
+    uint8_t channel[2];
+    uint8_t audio_channel;
+    uint8_t output_size;
+    uint8_t sample_spacing;
+    bool loop;
+    bool single_channel;
+    bool signed_to_unsigned;
+    bool unsigned_to_signed;
+    bool output_signed;
+    bool first_channel_free;
+    bool first_buffer_free;
+    uint8_t output_resolution; // in bits
+    uint8_t sample_resolution; // in bits
+    uint8_t* first_buffer;
+    uint8_t* second_buffer;
+    background_callback_t callback;
+} audio_dma_t;
+
+typedef enum {
+    AUDIO_DMA_OK,
+    AUDIO_DMA_DMA_BUSY,
+    AUDIO_DMA_MEMORY_ERROR,
+} audio_dma_result;
+
+
+void audio_dma_init(audio_dma_t* dma);
+void audio_dma_deinit(audio_dma_t* dma);
+void audio_dma_reset(void);
+
+// This sets everything up but doesn't start the timer.
+// Sample is the python object for the sample to play.
+// loop is true if we should loop the sample.
+// single_channel is true if we only output a single channel. When false, all channels will be
+//   output.
+// audio_channel is the index of the channel to dma. single_channel must be false in this case.
+// output_signed is true if the dma'd data should be signed. False and it will be unsigned.
+// output_register_address is the address to copy data to.
+// dma_trigger_source is the DMA trigger source which cause another copy
+audio_dma_result audio_dma_setup_playback(audio_dma_t* dma,
+                                          mp_obj_t sample,
+                                          bool loop,
+                                          bool single_channel,
+                                          uint8_t audio_channel,
+                                          bool output_signed,
+                                          uint8_t output_resolution,
+                                          uint32_t output_register_address,
+                                          uint8_t dma_trigger_source);
+
+void audio_dma_stop(audio_dma_t* dma);
+bool audio_dma_get_playing(audio_dma_t* dma);
+void audio_dma_pause(audio_dma_t* dma);
+void audio_dma_resume(audio_dma_t* dma);
+bool audio_dma_get_paused(audio_dma_t* dma);
+
+#endif  // MICROPY_INCLUDED_RASPBERRYPI_AUDIO_DMA_OUT_H