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Output I2S audio with PIO/DMA

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Requires a MAX98357A amplifier and a 2W 8ohms speaker
This commit is contained in:
Vincent Mistler
2022-12-02 17:24:39 +00:00
parent a9f54dc37d
commit 29a04ad832
8 changed files with 285 additions and 31 deletions
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src/main.c
+36 -8
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@@ -13,11 +13,11 @@
* PERFORMANCE OF THIS SOFTWARE.
*/
// Peanut-GB emulator settings
#define ENABLE_LCD 1
#ifndef ENABLE_SOUND
# define ENABLE_SOUND 0
#endif
#define ENABLE_SOUND 1
#define PEANUT_GB_HIGH_LCD_ACCURACY 1
#define PEANUT_GB_USE_BIOS 0
/* Use DMA for all drawing to LCD. Benefits aren't fully realised at the moment
* due to busy loops waiting for DMA completion. */
@@ -40,6 +40,7 @@
#include <string.h>
/* RP2040 Headers */
#include <hardware/pio.h>
#include <hardware/clocks.h>
#include <hardware/dma.h>
#include <hardware/spi.h>
@@ -55,8 +56,10 @@
/* Project headers */
#include "hedley.h"
#include "minigb_apu.h"
#include "peanut_gb.h"
#include "mk_ili9225.h"
#include "i2s.h"
/* GPIO Connections. */
#define GPIO_UP 2
@@ -75,6 +78,15 @@
#define GPIO_RST 21
#define GPIO_LED 22
#if ENABLE_SOUND
// Global variables for audio task
// stream contains N=AUDIO_SAMPLES samples
// each sample is 32 bits
// (16 bits for the left channel + 16 bits for the right channel in stereo interleaved format)
// This is intended to be played at AUDIO_SAMPLE_RATE Hz
uint16_t *stream;
#endif
/* DMA channel for LCD communication. */
static uint dma_lcd;
/* Definition of ROM data variable. Must be declared like:
@@ -206,6 +218,7 @@ void core1_irq_dma_lcd_end_transfer(void)
dma_channel_acknowledge_irq0(dma_lcd);
}
#if ENABLE_LCD
void core1_lcd_draw_line(const uint_fast8_t line)
{
const uint16_t palette[3][4] = {
@@ -317,6 +330,7 @@ void main_core1(void)
HEDLEY_UNREACHABLE();
}
#endif
#if ENABLE_LCD
void lcd_draw_line(struct gb_s *gb, const uint8_t pixels[LCD_WIDTH],
@@ -422,8 +436,10 @@ int main(void)
spi_set_format(spi0, 16, SPI_CPOL_0, SPI_CPHA_0, SPI_MSB_FIRST);
/* Start Core1, which processes requests to the LCD. */
#if ENABLE_LCD
putstdio("CORE1 ");
multicore_launch_core1(main_core1);
#endif
/* Initialise GB context. */
memcpy(rom_bank0, rom, sizeof(rom_bank0));
@@ -469,7 +485,20 @@ int main(void)
//gb.direct.interlace = 1;
#endif
#if ENABLE_SOUND
// Allocate memory for the stream buffer
stream=malloc(AUDIO_BUFFER_SIZE_BYTES);
assert(stream!=NULL);
memset(stream,0,AUDIO_BUFFER_SIZE_BYTES); // Zero out the stream buffer
// Initialize I2S sound driver
i2s_config_t i2s_config = i2s_get_default_config();
i2s_config.sample_freq=AUDIO_SAMPLE_RATE;
i2s_config.dma_trans_count =AUDIO_SAMPLES;
i2s_init(&i2s_config);
// Initialize audio emulation
audio_init();
putstdio("AUDIO ");
#endif
@@ -479,9 +508,6 @@ int main(void)
while(1)
{
int input;
#if ENABLE_SOUND
static uint16_t stream[1098];
#endif
gb.gb_frame = 0;
@@ -492,7 +518,9 @@ int main(void)
frames++;
#if ENABLE_SOUND
audio_callback(NULL, stream, 1098);
audio_callback(NULL, stream, AUDIO_BUFFER_SIZE_BYTES);
// i2s_write(&i2s_config,stream,AUDIO_SAMPLES);
i2s_dma_write(&i2s_config, stream);
#endif
/* Update buttons state */