Merge pull request #18 from mcscope/color_orders

Support Color Order setting

adafruit_dotstar.py

@@ -36,6 +36,17 @@ import digitalio
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_DotStar.git"
 
+START_HEADER_SIZE = 4
+
+# Pixel color order constants
+RGB = (0, 1, 2)
+RBG = (0, 2, 1)
+GRB = (1, 0, 2)
+GBR = (1, 2, 0)
+BRG = (2, 0, 1)
+BGR = (2, 1, 0)
+
+
 class DotStar:
     """
     A sequence of dotstars.
@@ -46,6 +57,9 @@ class DotStar:
     :param float brightness: Brightness of the pixels between 0.0 and 1.0
     :param bool auto_write: True if the dotstars should immediately change when
         set. If False, `show` must be called explicitly.
+    :param tuple pixel_order: Set the pixel order on the strip - different
+         strips implement this differently. If you send red, and it looks blue
+         or green on the strip, modify this! It should be one of the values above
 
 
     Example for Gemma M0:
@@ -63,7 +77,7 @@ class DotStar:
             time.sleep(2)
     """
 
-    def __init__(self, clock, data, n, *, brightness=1.0, auto_write=True):
+    def __init__(self, clock, data, n, *, brightness=1.0, auto_write=True, pixel_order=BGR):
         self._spi = None
         try:
             self._spi = busio.SPI(clock, MOSI=data)
@@ -77,19 +91,18 @@ class DotStar:
             self.cpin.direction = digitalio.Direction.OUTPUT
             self.cpin.value = False
         self._n = n
-        self.start_header_size = 4
         # Supply one extra clock cycle for each two pixels in the strip.
         self.end_header_size = n // 16
         if n % 16 != 0:
             self.end_header_size += 1
-        self._buf = bytearray(n * 4 + self.start_header_size + self.end_header_size)
+        self._buf = bytearray(n * 4 + START_HEADER_SIZE + self.end_header_size)
         self.end_header_index = len(self._buf) - self.end_header_size
-
+        self.pixel_order = pixel_order
         # Four empty bytes to start.
-        for i in range(self.start_header_size):
+        for i in range(START_HEADER_SIZE):
             self._buf[i] = 0x00
         # Mark the beginnings of each pixel.
-        for i in range(self.start_header_size, self.end_header_index, 4):
+        for i in range(START_HEADER_SIZE, self.end_header_index, 4):
             self._buf[i] = 0xff
         # 0xff bytes at the end.
         for i in range(self.end_header_index, len(self._buf)):
@@ -104,7 +117,7 @@ class DotStar:
     def deinit(self):
         """Blank out the DotStars and release the resources."""
         self.auto_write = False
-        for i in range(self.start_header_size, self.end_header_index):
+        for i in range(START_HEADER_SIZE, self.end_header_index):
             if i % 4 != 0:
                 self._buf[i] = 0
         self.show()
@@ -124,24 +137,19 @@ class DotStar:
         return "[" + ", ".join([str(x) for x in self]) + "]"
 
     def _set_item(self, index, value):
-        offset = index * 4 + self.start_header_size
-        r = 0
-        g = 0
-        b = 0
+        offset = index * 4 + START_HEADER_SIZE
+        rgb = value
         if isinstance(value, int):
-            r = value >> 16
-            g = (value >> 8) & 0xff
-            b = value & 0xff
-        else:
-            r, g, b = value
+            rgb = (value >> 16, (value >> 8) & 0xff, value & 0xff)
+
         # Each pixel starts with 0xFF, then red/green/blue. Although the data
         # sheet suggests using a global brightness in the first byte, we don't
         # do that because it causes further issues with persistence of vision
         # projects.
         self._buf[offset] = 0xff    # redundant; should already be set
-        self._buf[offset + 1] = b
-        self._buf[offset + 2] = g
-        self._buf[offset + 3] = r
+        self._buf[offset + 1] = rgb[self.pixel_order[0]]
+        self._buf[offset + 2] = rgb[self.pixel_order[1]]
+        self._buf[offset + 3] = rgb[self.pixel_order[2]]
 
     def __setitem__(self, index, val):
         if isinstance(index, slice):
@@ -164,14 +172,14 @@ class DotStar:
             out = []
             for in_i in range(*index.indices(self._n)):
                 out.append(
-                    tuple(self._buf[in_i * 4 + (3 - i) + self.start_header_size] for i in range(3)))
+                    tuple(self._buf[in_i * 4 + (3 - i) + START_HEADER_SIZE] for i in range(3)))
             return out
         if index < 0:
             index += len(self)
         if index >= self._n or index < 0:
             raise IndexError
         offset = index * 4
-        return tuple(self._buf[offset + (3 - i) + self.start_header_size]
+        return tuple(self._buf[offset + (3 - i) + START_HEADER_SIZE]
                      for i in range(3))
 
     def __len__(self):
@@ -217,10 +225,10 @@ class DotStar:
         if self.brightness < 1.0:
             buf = bytearray(self._buf)
             # Four empty bytes to start.
-            for i in range(self.start_header_size):
+            for i in range(START_HEADER_SIZE):
                 buf[i] = 0x00
-            for i in range(self.start_header_size, self.end_header_index):
-                buf[i] = self._buf[i] if i %4 == 0 else int(self._buf[i] * self._brightness)
+            for i in range(START_HEADER_SIZE, self.end_header_index):
+                buf[i] = self._buf[i] if i % 4 == 0 else int(self._buf[i] * self._brightness)
             # Four 0xff bytes at the end.
             for i in range(self.end_header_index, len(buf)):
                 buf[i] = 0xff