audiocore: Support swapping dclk and lrclk pins for I2S

Signed-off-by: Matthias Blankertz <matthias@blankertz.org>

software/modules/audiocore/audiocore.c

@@ -40,7 +40,7 @@ void __time_critical_func(core1_main)(void)
 {
     uint32_t ret = 0;
     bool running = true, playing = false;
-    if (!i2s_init(shared_context.out_pin, shared_context.sideset_base)) {
+    if (!i2s_init(shared_context.out_pin, shared_context.sideset_base, shared_context.sideset_dclk_first)) {
         ret = MP_EIO;
         goto out;
     }

software/modules/audiocore/audiocore.h

@@ -31,6 +31,7 @@ struct audiocore_shared_context {
 
     // Set by module.c before core1 is launched and then never changed, can be read without lock
     int out_pin, sideset_base, samplerate;
+    bool sideset_dclk_first;
 
     // Must hold lock. The indices 0..MP3_BUFFER_PREAREA-1 may only be read and written on core1 (no
     // lock needed) The buffer is aligned to, and MP3_BUFFER_PREAREA is a multiple of, the machine

software/modules/audiocore/audiocore.py

@@ -8,11 +8,10 @@ from utils import get_pin_index
 
 class Audiocore:
     def __init__(self, din, dclk, lrclk):
-        assert get_pin_index(lrclk) == get_pin_index(dclk)+1  # TODO: Support different pin arrangements
+        # PIO requires sideset pins to be adjacent
+        assert get_pin_index(lrclk) == get_pin_index(dclk)+1 or get_pin_index(lrclk) == get_pin_index(dclk)-1
         self.notify = ThreadSafeFlag()
-        self.pin = din
-        self.sideset = dclk
-        self._audiocore = _audiocore.Audiocore(self.pin, self.sideset, self._interrupt)
+        self._audiocore = _audiocore.Audiocore(din, dclk, lrclk, self._interrupt)
 
     def deinit(self):
         self._audiocore.deinit()

software/modules/audiocore/i2s.c

@@ -113,17 +113,18 @@ void i2s_stop(void)
     pio_sm_clear_fifos(audiocore_pio, i2s_context.pio_sm);
 }
 
-bool i2s_init(int out_pin, int sideset_base)
+bool i2s_init(int out_pin, int sideset_base, bool dclk_first)
 {
     memset(i2s_context.dma_buf, 0, sizeof(i2s_context.dma_buf[0][0]) * AUDIO_BUFS * I2S_DMA_BUF_SIZE);
-    if (!pio_can_add_program(audiocore_pio, (const pio_program_t *)&i2s_max98357_program))
+    const pio_program_t *program = dclk_first ? &i2s_max98357_program : &i2s_max98357_lrclk_program;
+    if (!pio_can_add_program(audiocore_pio, program))
         return false;
     i2s_context.pio_sm = pio_claim_unused_sm(audiocore_pio, false);
     i2s_context.out_pin = out_pin;
     i2s_context.sideset_base = sideset_base;
     if (i2s_context.pio_sm == -1)
         return false;
-    i2s_context.pio_program_offset = pio_add_program(audiocore_pio, (const pio_program_t *)&i2s_max98357_program);
+    i2s_context.pio_program_offset = pio_add_program(audiocore_pio, program);
 
     i2s_context.dma_ch = dma_claim_unused_channel(false);
     if (i2s_context.dma_ch == -1)

software/modules/audiocore/i2s.h

@@ -8,7 +8,7 @@
 
 #define I2S_DMA_BUF_SIZE (1152)
 
-bool i2s_init(int out_pin, int sideset_base);
+bool i2s_init(int out_pin, int sideset_base, bool dclk_first);
 void i2s_deinit(void);
 
 void i2s_play(int samplerate);

software/modules/audiocore/i2s_max98357.pio

@@ -10,7 +10,7 @@
 	.lang_opt python autopull = True
 	
 // data - DOUT
-// sideset - 2-BCLK, 1-LRCLK
+// sideset - 2-LRCLK, 1-BCLK
 
 	set	x,15			side 0
 	nop				side 1
@@ -33,6 +33,38 @@ right_loop:
 	set	x, 14			side 1
 	.wrap
 
+.program i2s_max98357_lrclk
+	.side_set 2
+
+	.lang_opt python sideset_init = pico.PIO.OUT_LOW
+	.lang_opt python out_init = pico.PIO.OUT_LOW
+	.lang_opt python out_shiftdir = pcio.PIO.SHIFT_LEFT
+	.lang_opt python autopull = True
+	
+// data - DOUT
+// sideset - 2-BCLK, 1-LRCLK
+
+	set	x,15			side 0
+	nop				side 2
+startup_loop:
+	nop				side 1
+	jmp	x-- startup_loop	side 3
+	nop				side 0
+	set	x, 14			side 2
+
+left_loop:
+	.wrap_target
+	out	pins, 1			side 0
+	jmp	x-- left_loop		side 2
+	out	pins, 1			side 1
+	set	x, 14			side 3
+right_loop:	
+	out	pins, 1			side 1
+	jmp	x-- right_loop		side 3
+	out	pins, 1			side 0
+	set	x, 14			side 2
+	.wrap
+
 % c-sdk {
 #include "hardware/clocks.h"
 

software/modules/audiocore/module.c

@@ -170,10 +170,11 @@ static MP_DEFINE_CONST_FUN_OBJ_2(audiocore_set_volume_obj, audiocore_set_volume)
  */
 static void audiocore_init(struct audiocore_obj *obj, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args)
 {
-    enum { ARG_pin, ARG_sideset, ARG_handler };
+    enum { ARG_pin, ARG_dclk, ARG_lrclk, ARG_handler };
     static const mp_arg_t allowed_args[] = {
         {MP_QSTR_pin, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL}},
-        {MP_QSTR_sideset, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL}},
+        {MP_QSTR_dclk, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL}},
+        {MP_QSTR_lrclk, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL}},
         {MP_QSTR_handler, MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL}},
     };
     if (initialized)
@@ -188,7 +189,8 @@ static void audiocore_init(struct audiocore_obj *obj, size_t n_args, const mp_ob
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
     const mp_hal_pin_obj_t pin = mp_hal_get_pin_obj(args[ARG_pin].u_obj);
-    const mp_hal_pin_obj_t sideset_pin = mp_hal_get_pin_obj(args[ARG_sideset].u_obj);
+    const mp_hal_pin_obj_t dclk_pin = mp_hal_get_pin_obj(args[ARG_dclk].u_obj);
+    const mp_hal_pin_obj_t lrclk_pin = mp_hal_get_pin_obj(args[ARG_lrclk].u_obj);
     if (args[ARG_handler].u_obj != MP_OBJ_NULL) {
         obj->irq_obj = mp_irq_new(&audiocore_irq_methods, MP_OBJ_FROM_PTR(obj));
         obj->irq_obj->handler = args[ARG_handler].u_obj;
@@ -203,7 +205,14 @@ static void audiocore_init(struct audiocore_obj *obj, size_t n_args, const mp_ob
     memset(shared_context.mp3_buffer, 0, MP3_BUFFER_PREAREA + MP3_BUFFER_SIZE);
     multicore_reset_core1();
     shared_context.out_pin = pin;
-    shared_context.sideset_base = sideset_pin;
+    // PIO requires sideset pins to be adjacent, but we support both dclk first and lrclk first
+    if (lrclk_pin == dclk_pin + 1) {
+        shared_context.sideset_base = dclk_pin;
+        shared_context.sideset_dclk_first = true;
+    } else {
+        shared_context.sideset_base = lrclk_pin;
+        shared_context.sideset_dclk_first = false;
+    }
     initialized = true;
     multicore_launch_core1(&core1_main);
     uint32_t result = get_fifo_read_value_blocking(obj);

software/modules/audiocore/test/test_audiocore.c

@@ -15,7 +15,7 @@ static unsigned multicore_fifo_push_last;
 
 static unsigned (*multicore_fifo_pop_blocking_cb)(void);
 
-bool i2s_init(int out_pin, int sideset_base)
+bool i2s_init(int out_pin, int sideset_base, bool dclk_first)
 {
     TEST_ASSERT_FALSE(i2s_initialized);
     if (i2s_init_return)