Add Pico Audio Pack example

examples/CMakeLists.txt

@@ -6,4 +6,5 @@ add_subdirectory(pico_scroll)
 add_subdirectory(pico_explorer)
 add_subdirectory(pico_rgb_keypad)
 add_subdirectory(pico_rtc_display)
-add_subdirectory(pico_tof_display)
+add_subdirectory(pico_tof_display)
+add_subdirectory(pico_audio)

examples/pico_audio/CMakeLists.txt

@@ -0,0 +1,23 @@
+if (TARGET pico_audio_i2s)
+    # You must supply the Pico Extras path to build this example
+    # -DPICO_SDK_POST_LIST_DIRS=/path/to/pico-extras
+    # You can use "cmake.configureSettings" in VSCode settings.json
+    # Grab the extra libraries here: https://github.com/raspberrypi/pico-extras
+    add_executable(
+    audio
+    demo.cpp
+    )
+
+    # Pull in pico libraries that we need
+    target_link_libraries(audio pico_stdlib pico_audio_i2s)
+
+    target_compile_definitions(audio PRIVATE
+    # compile time configuration of I2S
+    PICO_AUDIO_I2S_MONO_INPUT=1
+    #define for our example code
+    USE_AUDIO_I2S=1
+    )
+
+    # create map/bin/hex file etc.
+    pico_add_extra_outputs(audio)
+endif()

examples/pico_audio/demo.cpp

@@ -0,0 +1,97 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdio.h>
+#include <math.h>
+
+#if PICO_ON_DEVICE
+
+#include "hardware/clocks.h"
+#include "hardware/structs/clocks.h"
+
+#endif
+
+#include "pico/stdlib.h"
+#include "pico/audio_i2s.h"
+
+#define PICO_AUDIO_PAC_I2S_DATA 9
+#define PICO_AUDIO_PAC_I2S_BITCLOCK 10
+#define SINE_WAVE_TABLE_LEN 2048
+#define SAMPLES_PER_BUFFER 256
+
+static int16_t sine_wave_table[SINE_WAVE_TABLE_LEN];
+
+struct audio_buffer_pool *init_audio() {
+
+    static audio_format_t audio_format = {
+            .sample_freq = 24000,
+            .format = AUDIO_BUFFER_FORMAT_PCM_S16,
+            .channel_count = 1,
+    };
+
+    static struct audio_buffer_format producer_format = {
+            .format = &audio_format,
+            .sample_stride = 2
+    };
+
+    struct audio_buffer_pool *producer_pool = audio_new_producer_pool(&producer_format, 3,
+                                                                      SAMPLES_PER_BUFFER); // todo correct size
+    bool __unused ok;
+    const struct audio_format *output_format;
+    struct audio_i2s_config config = {
+            .data_pin = PICO_AUDIO_PAC_I2S_DATA,
+            .clock_pin_base = PICO_AUDIO_PAC_I2S_BITCLOCK,
+            .dma_channel = 0,
+            .pio_sm = 0,
+    };
+
+    output_format = audio_i2s_setup(&audio_format, &config);
+    if (!output_format) {
+        panic("PicoAudio: Unable to open audio device.\n");
+    }
+
+    ok = audio_i2s_connect(producer_pool);
+    assert(ok);
+    audio_i2s_set_enabled(true);
+
+    return producer_pool;
+}
+
+int main() {
+    stdio_init_all();
+
+    for (int i = 0; i < SINE_WAVE_TABLE_LEN; i++) {
+        sine_wave_table[i] = 32767 * cosf(i * 2 * (float) (M_PI / SINE_WAVE_TABLE_LEN));
+    }
+
+    struct audio_buffer_pool *ap = init_audio();
+    uint32_t step = 0x200000;
+    uint32_t pos = 0;
+    uint32_t pos_max = 0x10000 * SINE_WAVE_TABLE_LEN;
+    uint vol = 128;
+    while (true) {
+        int c = getchar_timeout_us(0);
+        if (c >= 0) {
+            if (c == '-' && vol) vol -= 4;
+            if ((c == '=' || c == '+') && vol < 255) vol += 4;
+            if (c == '[' && step > 0x10000) step -= 0x10000;
+            if (c == ']' && step < (SINE_WAVE_TABLE_LEN / 16) * 0x20000) step += 0x10000;
+            if (c == 'q') break;
+            printf("vol = %d, step = %d      \r", vol, step >> 16);
+        }
+        struct audio_buffer *buffer = take_audio_buffer(ap, true);
+        int16_t *samples = (int16_t *) buffer->buffer->bytes;
+        for (uint i = 0; i < buffer->max_sample_count; i++) {
+            samples[i] = (vol * sine_wave_table[pos >> 16u]) >> 8u;
+            pos += step;
+            if (pos >= pos_max) pos -= pos_max;
+        }
+        buffer->sample_count = buffer->max_sample_count;
+        give_audio_buffer(ap, buffer);
+    }
+    puts("\n");
+    return 0;
+}