nRF52: Add support for sound output over I2S

Makefile

@@ -679,6 +679,11 @@ ifeq ($(USE_JIT),1)
   SOURCES += src/jsjit.c src/jsjitc.c
 endif
 
+ifeq ($(USE_I2S),1)
+  DEFINES += -DUSE_I2S
+  WRAPPERSOURCES += src/jswrap_i2s.c
+endif
+
 
 endif # BOOTLOADER ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ DON'T USE STUFF ABOVE IN BOOTLOADER
 

boards/JOLTJS.py

@@ -35,7 +35,8 @@
      'GRAPHICS',
 #     'NFC',
      'NEOPIXEL',
-     'JIT' # JIT compiler enabled
+     'JIT', # JIT compiler enabled
+     'I2S'
    ],
    'makefile' : [
      'DEFINES+=-DESPR_OFFICIAL_BOARD', # Don't display the donations nag screen

boards/XIAOBLE.py

@@ -47,6 +47,7 @@
             # "TENSORFLOW",
             "NEOPIXEL",
             "JIT",
+            "I2S",
         ],
         "makefile": [
             "DEFINES += -DESPR_LSE_ENABLE",  # Ensure low speed external osc enabled

make/common/NRF5X.make

@@ -83,6 +83,10 @@ else # no BOOTLOADER
     # Neopixel support (only NRF52)
     SOURCES    += targets/nrf5x/i2s_ws2812b_drive.c
   endif
+  ifeq ($(USE_I2S),1)
+    # I2S support
+    SOURCES += targets/nrf5x/jsi2s.c
+  endif
 endif
 
 # Careful here.. All these includes and sources assume a SoftDevice. Not efficient/clean if softdevice (ble) is not enabled...

src/jsi2s.h

@@ -0,0 +1,37 @@
+/*
+ * This file is part of Espruino, a JavaScript interpreter for Microcontrollers
+ *
+ * Copyright (C) 2025 Simon Sievert <[email protected]>
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * ----------------------------------------------------------------------------
+ * I2S support
+ * ----------------------------------------------------------------------------
+ */
+
+#ifndef JSI2S_H
+#define JSI2S_H
+
+#include "jspin.h"
+
+typedef void (*jsi2s_data_cb_t)(void);
+
+typedef void (*jsi2s_buffer_release_cb_t)(uint32_t *buf_ptr);
+
+bool jsi2s_init(Pin bclk, Pin lrck, Pin dout, int sample_width_bytes);
+
+void jsi2s_uninit();
+
+bool jsi2s_start(uint32_t *buf_ptr, uint32_t buffer_size_bytes, jsi2s_data_cb_t data_callback,
+                 jsi2s_buffer_release_cb_t buffer_released_callback);
+
+void jsi2s_stop();
+
+bool jsi2s_set_next_buffer(uint32_t *buf_ptr, uint32_t buffer_size_bytes);
+
+bool jsi2s_idle();
+
+#endif // JSI2S_H