Change buffers to int32_t to accomodate signed data from I2S

.gitignore

@@ -0,0 +1,4 @@
+.DS_Store
+.idea
+cmake-*
+build/

CMakeLists.txt

@@ -22,28 +22,40 @@ cmake_minimum_required(VERSION 3.13)
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_CXX_STANDARD 17)
 
-# Initialise pico_sdk from installed location
-# (note this can come from environment, CMake cache etc)
-set(PICO_SDK_PATH "/Users/studiodc/Development/raspi/pico/sdk")
+
+# Set standard CMake build type options
+## Default C compiler flags
+set(CMAKE_C_FLAGS_DEBUG_INIT "-g3 -Og -Wall -Wextra -DDEBUG")
+set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG_INIT}" CACHE STRING "" FORCE)
+set(CMAKE_C_FLAGS_RELEASE_INIT "-O3 -Wall")
+set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE_INIT}" CACHE STRING "" FORCE)
+set(CMAKE_C_FLAGS_MINSIZEREL_INIT "-Os -Wall")
+set(CMAKE_C_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL_INIT}" CACHE STRING "" FORCE)
+set(CMAKE_C_FLAGS_RELWITHDEBINFO_INIT "-O2 -g -Wall")
+set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_ASM_FLAGS_RELWITHDEBINFO_INIT}" CACHE STRING "" FORCE)
+## Default C++ compiler flags
+set(CMAKE_CXX_FLAGS_DEBUG_INIT "-g3 -Og -Wall -Wextra -DDEBUG")
+set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG_INIT}" CACHE STRING "" FORCE)
+set(CMAKE_CXX_FLAGS_RELEASE_INIT "-O3 -Wall")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE_INIT}" CACHE STRING "" FORCE)
+set(CMAKE_CXX_FLAGS_MINSIZEREL_INIT "-Os -Wall")
+set(CMAKE_CXX_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL_INIT}" CACHE STRING "" FORCE)
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT "-O2 -g -Wall")
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_ASM_FLAGS_RELWITHDEBINFO_INIT}" CACHE STRING "" FORCE)
 
 # Pull in Raspberry Pi Pico SDK (must be before project)
 include(pico_sdk_import.cmake)
-
 project(i2s_example C CXX ASM)
-
-# Initialise the Raspberry Pi Pico SDK
 pico_sdk_init()
 
-# Add executable. Default name is the project name, version 0.1
-
 add_executable(i2s_example i2s.c)
 
 pico_generate_pio_header(i2s_example ${CMAKE_CURRENT_LIST_DIR}/i2s.pio)
 
 target_sources(i2s_example PRIVATE i2s_example.c)
 
 pico_set_program_name(i2s_example "i2s_test")
-pico_set_program_version(i2s_example "0.1")
+pico_set_program_version(i2s_example "1.0.1")
 
 # no_flash means the target is to run from RAM
 # pico_set_binary_type(i2s_test no_flash)

i2s.h

@@ -63,10 +63,10 @@ typedef struct pio_i2s {
     uint       dma_ch_in_data;
     uint       dma_ch_out_ctrl;
     uint       dma_ch_out_data;
-    uint32_t*  in_ctrl_blocks[2];  // Control blocks MUST have 8-byte alignment.
-    uint32_t*  out_ctrl_blocks[2];
-    uint32_t   input_buffer[STEREO_BUFFER_SIZE * 2];
-    uint32_t   output_buffer[STEREO_BUFFER_SIZE * 2];
+    int32_t*   in_ctrl_blocks[2];  // Control blocks MUST have 8-byte alignment.
+    int32_t*   out_ctrl_blocks[2];
+    int32_t    input_buffer[STEREO_BUFFER_SIZE * 2];
+    int32_t    output_buffer[STEREO_BUFFER_SIZE * 2];
     i2s_config config;
 } pio_i2s;
 

i2s_example.c

@@ -47,7 +47,7 @@ const uint LED_PIN = PICO_DEFAULT_LED_PIN;
 
 static __attribute__((aligned(8))) pio_i2s i2s;
 
-static void process_audio(const uint32_t* input, uint32_t* output, size_t num_frames) {
+static void process_audio(const int32_t* input, int32_t* output, size_t num_frames) {
     // Just copy the input to the output
     for (size_t i = 0; i < num_frames * 2; i++) {
         output[i] = input[i];
@@ -59,7 +59,7 @@ static void dma_i2s_in_handler(void) {
      * DMA is currently reading from, we can identify which buffer it has just
      * finished reading (the completion of which has triggered this interrupt).
      */
-    if (*(uint32_t**)dma_hw->ch[i2s.dma_ch_in_ctrl].read_addr == i2s.input_buffer) {
+    if (*(int32_t**)dma_hw->ch[i2s.dma_ch_in_ctrl].read_addr == i2s.input_buffer) {
         // It is inputting to the second buffer so we can overwrite the first
         process_audio(i2s.input_buffer, i2s.output_buffer, AUDIO_BUFFER_FRAMES);
     } else {