codal_port: Add "neopixel" module.

This module is frozen Python code, and backed by the low-level
microbit.ws2821_write function.  It should be compatible with micro:bit v1,
and also includes support for RGBW LEDs.

Author: dpgeorge

src/codal_port/Makefile

@@ -1,5 +1,7 @@
 # Makefile to build libmicropython.a
 
+FROZEN_MANIFEST ?= manifest.py
+
 CROSS_COMPILE = arm-none-eabi-
 CFLAGS_EXTRA = -mthumb -mtune=cortex-m4 -mcpu=cortex-m4
 

src/codal_port/manifest.py

@@ -0,0 +1 @@
+freeze("modules", "neopixel.py", opt=3)

src/codal_port/modmicrobit.c

@@ -82,6 +82,15 @@ STATIC mp_obj_t microbit_set_volume(mp_obj_t volume_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(microbit_set_volume_obj, microbit_set_volume);
 
+STATIC mp_obj_t microbit_ws2812_write(mp_obj_t pin_in, mp_obj_t buf_in) {
+    uint8_t pin = microbit_obj_get_pin(pin_in)->name;
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_READ);
+    microbit_hal_pin_write_ws2812(pin, bufinfo.buf, bufinfo.len);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(microbit_ws2812_write_obj, microbit_ws2812_write);
+
 STATIC const mp_rom_map_elem_t microbit_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_microbit) },
 
@@ -104,6 +113,7 @@ STATIC const mp_rom_map_elem_t microbit_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_panic), MP_ROM_PTR(&microbit_panic_obj) },
     { MP_ROM_QSTR(MP_QSTR_temperature), MP_ROM_PTR(&microbit_temperature_obj) },
     { MP_ROM_QSTR(MP_QSTR_set_volume), MP_ROM_PTR(&microbit_set_volume_obj) },
+    { MP_ROM_QSTR(MP_QSTR_ws2812_write), MP_ROM_PTR(&microbit_ws2812_write_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_pin0), MP_ROM_PTR(&microbit_p0_obj) },
     { MP_ROM_QSTR(MP_QSTR_pin1), MP_ROM_PTR(&microbit_p1_obj) },

src/codal_port/modules/neopixel.py

@@ -0,0 +1,42 @@
+# NeoPixel driver for MicroPython
+# MIT license; Copyright (c) 2016-2020 Damien P. George
+
+from microbit import ws2812_write
+
+
+class NeoPixel:
+    ORDER = (1, 0, 2, 3)
+
+    def __init__(self, pin, n, bpp=3):
+        self.pin = pin
+        self.n = n
+        self.bpp = bpp
+        self.buf = bytearray(n * bpp)
+
+    def __setitem__(self, index, val):
+        offset = index * self.bpp
+        for i in range(self.bpp):
+            self.buf[offset + self.ORDER[i]] = val[i]
+
+    def __getitem__(self, index):
+        offset = index * self.bpp
+        return tuple(self.buf[offset + self.ORDER[i]] for i in range(self.bpp))
+
+    def fill(self, color):
+        for i in range(self.n):
+            self[i] = color
+
+    def write(self):
+        ws2812_write(self.pin, self.buf)
+
+    # microbit v1 methods
+
+    def __len__(self):
+        return self.n
+
+    def clear(self):
+        for i in range(len(self.buf)):
+            self.buf[i] = 0
+        self.write()
+
+    show = write

src/codal_port/mpconfigport.h

@@ -54,6 +54,8 @@
 #define MICROPY_FLOAT_IMPL                      (MICROPY_FLOAT_IMPL_FLOAT)
 #define MICROPY_MODULE_BUILTIN_INIT             (1)
 #define MICROPY_MODULE_WEAK_LINKS               (1)
+#define MICROPY_MODULE_FROZEN_MPY               (1)
+#define MICROPY_QSTR_EXTRA_POOL                 mp_qstr_frozen_const_pool
 #define MICROPY_ENABLE_SCHEDULER                (1)
 
 // Fine control over Python builtins, classes, modules, etc