remove i2sin invert_bit_clock argument

ports/espressif/common-hal/audioi2sin/I2SIn.c

@@ -25,7 +25,7 @@ void common_hal_audioi2sin_i2sin_construct(audioi2sin_i2sin_obj_t *self,
     const mcu_pin_obj_t *data, const mcu_pin_obj_t *main_clock,
     uint32_t sample_rate, uint8_t bit_depth, uint8_t output_bit_depth,
     bool mono, bool left_justified, bool samples_signed,
-    bool external_clock, bool invert_bit_clock) {
+    bool external_clock) {
     if (external_clock) {
         mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_external_clock);
     }

ports/raspberrypi/common-hal/audioi2sin/I2SIn.c

@@ -212,11 +212,10 @@ static const uint16_t i2sin_program_left_justified_swap_32[] = {
 // a 32-BCLK frame is one push (right<<16 | left), at 24/32 a 64-BCLK frame is
 // two pushes (right then left).
 //
-// The resync's own `wait 0/1 gpio B` already lands on the first data bit, so
-// against a CircuitPython clock source this program recovers the transmitted word
-// bit-exactly with no instruction for the Philips delay bit. The
-// `left_justified` variant is that program plus one more BCLK of skew,
-// the other of the two possible alignments;
+// The WS resync lands on the first data bit, so the program above is
+// the `left_justified` alignment: data starts on the WS edge and no instruction
+// is spent on a delay bit. The default (Philips) alignment is that program plus
+// one more BCLK of skew, the other of the two possible alignments.
 //
 // Free-running after the initial sync: the external frame must be exactly
 // 2 x bits_per_channel BCLKs, the same assumption internal clock mode already bakes
@@ -226,12 +225,9 @@ static const uint16_t i2sin_program_left_justified_swap_32[] = {
 #define I2SIN_EXT_CLOCK_WRAP_TARGET(len) ((int)(len) - 5)
 
 static size_t build_i2sin_ext_clock_program(uint16_t *prog, uint8_t bclk, uint8_t ws,
-    bool left_justified, bool invert_bit_clock) {
-    // Sampling on the falling edge of BCLK is the same program with the
-    // polarity of every BCLK wait flipped.
-    const uint16_t invert = invert_bit_clock ? 0x0080 : 0x0000;
-    const uint16_t wait_0_bclk = (0x2000 | bclk) ^ invert;
-    const uint16_t wait_1_bclk = (0x2080 | bclk) ^ invert;
+    bool left_justified) {
+    const uint16_t wait_0_bclk = 0x2000 | bclk;
+    const uint16_t wait_1_bclk = 0x2080 | bclk;
     size_t len = 0;
     prog[len++] = 0x2000 | ws;  // wait 0 gpio W
     prog[len++] = 0x2080 | ws;  // wait 1 gpio W
@@ -262,7 +258,7 @@ void common_hal_audioi2sin_i2sin_construct(audioi2sin_i2sin_obj_t *self,
     const mcu_pin_obj_t *data, const mcu_pin_obj_t *main_clock,
     uint32_t sample_rate, uint8_t bit_depth, uint8_t output_bit_depth,
     bool mono, bool left_justified, bool samples_signed,
-    bool external_clock, bool invert_bit_clock) {
+    bool external_clock) {
 
     if (main_clock != NULL) {
         mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_main_clock);
@@ -295,7 +291,7 @@ void common_hal_audioi2sin_i2sin_construct(audioi2sin_i2sin_obj_t *self,
         program_len = build_i2sin_ext_clock_program(ext_clock_program,
             i2s_wait_gpio_index(bit_clock, gpio_offset),
             i2s_wait_gpio_index(word_select, gpio_offset),
-            left_justified, invert_bit_clock);
+            left_justified);
         program = ext_clock_program;
         wait_gpio_mask = PIO_PINMASK_OR(PIO_PINMASK_FROM_PIN(bit_clock->number),
             PIO_PINMASK_FROM_PIN(word_select->number));

shared-bindings/audioi2sin/I2SIn.c

@@ -35,7 +35,6 @@
 //|         left_justified: bool = False,
 //|         samples_signed: bool = True,
 //|         external_clock: bool = False,
-//|         invert_bit_clock: bool = False,
 //|     ) -> None:
 //|         """Create an I2SIn object associated with the given pins. This allows you to
 //|         record audio signals from an external I2S source (e.g. an I2S MEMS microphone
@@ -95,9 +94,6 @@
 //|           declaration rather than a measurement: the real rate is whatever the external word select
 //|           runs at, and `sample_rate` still reports the declared value. If the incoming clock stops,
 //|           `record` blocks (interruptible with Ctrl-C).
-//|         :param bool invert_bit_clock: Sample ``data`` on the falling edge of ``bit_clock`` instead of
-//|           the rising edge. Needed when the external clock source drives its data on the rising edge.
-//|           Only valid together with ``external_clock``.
 //|
 //|         Example, recording 16-bit mono samples from an INMP441::
 //|
@@ -121,7 +117,7 @@ static mp_obj_t audioi2sin_i2sin_make_new(const mp_obj_type_t *type, size_t n_ar
     enum { ARG_bit_clock, ARG_word_select, ARG_data, ARG_main_clock,
            ARG_sample_rate, ARG_bit_depth, ARG_output_bit_depth,
            ARG_mono, ARG_left_justified, ARG_samples_signed,
-           ARG_external_clock, ARG_invert_bit_clock };
+           ARG_external_clock };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_bit_clock,        MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_word_select,      MP_ARG_REQUIRED | MP_ARG_OBJ },
@@ -134,17 +130,11 @@ static mp_obj_t audioi2sin_i2sin_make_new(const mp_obj_type_t *type, size_t n_ar
         { MP_QSTR_left_justified,   MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
         { MP_QSTR_samples_signed,   MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = true} },
         { MP_QSTR_external_clock,   MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
-        { MP_QSTR_invert_bit_clock, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
     };
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
 
     bool external_clock = args[ARG_external_clock].u_bool;
-    bool invert_bit_clock = args[ARG_invert_bit_clock].u_bool;
-    if (invert_bit_clock && !external_clock) {
-        mp_raise_ValueError_varg(MP_ERROR_TEXT("%q requires %q"),
-            MP_QSTR_invert_bit_clock, MP_QSTR_external_clock);
-    }
 
     // In external clock mode the clock pins are only read, so they may already
     // be owned by whatever is driving them; let the port decide if the sharing
@@ -181,7 +171,7 @@ static mp_obj_t audioi2sin_i2sin_make_new(const mp_obj_type_t *type, size_t n_ar
     audioi2sin_i2sin_obj_t *self = mp_obj_malloc_with_finaliser(audioi2sin_i2sin_obj_t, &audioi2sin_i2sin_type);
     common_hal_audioi2sin_i2sin_construct(self, bit_clock, word_select, data, main_clock,
         sample_rate, bit_depth, output_bit_depth, mono, left_justified, samples_signed,
-        external_clock, invert_bit_clock);
+        external_clock);
 
     return MP_OBJ_FROM_PTR(self);
     #endif

shared-bindings/audioi2sin/I2SIn.h

@@ -21,7 +21,7 @@ void common_hal_audioi2sin_i2sin_construct(audioi2sin_i2sin_obj_t *self,
     const mcu_pin_obj_t *data, const mcu_pin_obj_t *main_clock,
     uint32_t sample_rate, uint8_t bit_depth, uint8_t output_bit_depth,
     bool mono, bool left_justified, bool samples_signed,
-    bool external_clock, bool invert_bit_clock);
+    bool external_clock);
 void common_hal_audioi2sin_i2sin_deinit(audioi2sin_i2sin_obj_t *self);
 bool common_hal_audioi2sin_i2sin_deinited(audioi2sin_i2sin_obj_t *self);
 uint32_t common_hal_audioi2sin_i2sin_record_to_buffer(audioi2sin_i2sin_obj_t *self,