jepler/Adafruit_CircuitPython_NeoPxl8
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Support 1-pixel strips

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.. this calls for a different memory layout to save memory size in the
'background' buffer
This commit is contained in:
Jeff Epler 2022-11-16 10:12:25 -06:00
parent 377e59b944
commit c86c6c0b62
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GPG key ID: D5BF15AB975AB4DE
1 changed files with 50 additions and 7 deletions
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57
adafruit_neopxl8.py
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@ -74,6 +74,33 @@ wait_reset:
jmp top
"""
_PROGRAM1 = """
.program piopixl8
top:
mov pins, null ; always-low part (last cycle is the 'pull ifempty' after wrap)
pull block ; wait for fresh data
out y, 32 ; get count of NeoPixel bits
; NeoPixels are 800khz bit streams. We are choosing zeros as <312ns hi, 936 lo>
; and ones as <700 ns hi, 546 ns lo> and a clock of 16*800kHz, so the always-high
; time is 4 cycles, the variable time is 5 cycles, and the always-low time is 7 cycles
bitloop:
pull ifempty [1] ; don't start outputting HIGH unless data is available (always-low part)
mov pins, ~ null [3] ; always-high part
out pins, 1 [4] ; variable part
mov pins, null ; always-low part (last cycle is the 'pull ifempty' after wrap)
jmp y--, bitloop ; always-low part
; A minimum delay is required so that the next pixel starts refreshing the front of the strands
pull block
out y, 32
wait_reset:
jmp y--, wait_reset
jmp top
"""
# Pixel color order constants
RGB = "RGB"
"""Red Green Blue"""
@ -150,19 +177,31 @@ class NeoPxl8(adafruit_pixelbuf.PixelBuf):
n, brightness=brightness, byteorder=pixel_order, auto_write=auto_write
)
data_len = bpp * n * 8 // num_strands
if num_strands == 1:
data_len = bpp * n
pack = ">L"
osr = False
n = (8 * data_len) - 1
else:
data_len = bpp * n * 8 // num_strands
pack = "<L"
osr = True
n = data_len - 1
padding_count = -data_len % 4
self._num_strands = num_strands
self._data = bytearray(8 + data_len + padding_count)
self._data32 = memoryview(self._data).cast("L")
self._transposed = memoryview(self._data)[4 : 4 + data_len]
self._data[:4] = struct.pack("<L", data_len - 1)
self._data[-4:] = struct.pack("<L", 3840 * 2)
self._pixels = memoryview(self._data)[4 : 4 + data_len]
self._data[:4] = struct.pack(pack, n)
self._data[-4:] = struct.pack(pack, 3840 * 2)
self._num_strands = num_strands
if num_strands == 8:
assembled = adafruit_pioasm.assemble(_PROGRAM8)
elif num_strands == 1:
assembled = adafruit_pioasm.assemble(_PROGRAM1)
else:
program = _PROGRAMN.format(num_strands, 8 - num_strands)
assembled = adafruit_pioasm.assemble(program)
@ -174,7 +213,7 @@ class NeoPxl8(adafruit_pixelbuf.PixelBuf):
out_pin_count=num_strands,
first_set_pin=data0,
auto_pull=False,
out_shift_right=True,
out_shift_right=osr,
)
def deinit(self):
@ -209,5 +248,9 @@ class NeoPxl8(adafruit_pixelbuf.PixelBuf):
def _transmit(self, buffer):
while self._sm.pending:
pass
bitops.bit_transpose(buffer, self._transposed, self._num_strands)
self._sm.background_write(self._data32)
if self.num_strands == 1:
self._pixels[:] = buffer
self._sm.background_write(self._data32, swap=True)
else:
bitops.bit_transpose(buffer, self._pixels, self._num_strands)
self._sm.background_write(self._data32)