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switch bit count from 16 bits to 32 bits, explain how auto_write behaves

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Jeff Epler 2022-05-07 09:47:39 -05:00
parent 082e0a1dc6
commit 7e9076dae2
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1 changed files with 12 additions and 14 deletions
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26
examples/pioasm_neopixel_bg.py
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@ -6,7 +6,8 @@
The NeoPixelBackground class defined here is largely compatible with the
standard NeoPixel class, except that the ``show()`` method returns immediately,
writing data to the LEDs in the background.
writing data to the LEDs in the background, and setting `auto_write` to true
causes the data to be continuously sent to the LEDs all the time.
Writing the LED data in the background will allow more time for your
Python code to run, so it may be possible to slightly increase the refresh
@ -43,7 +44,7 @@ _program = Program(
.side_set 1 opt
.wrap_target
pull block side 0
out y, 16 side 0 ; get count of NeoPixel bits
out y, 32 side 0 ; get count of NeoPixel bits
bitloop:
pull ifempty side 0 ; drive low
@ -56,8 +57,8 @@ do_zero:
jmp y--, bitloop side 0 [4] ; drive low for a zero (short pulse)
end_sequence:
pull block side 0 ; get fresh 16 bit delay value
out y, 16 side 0 ; get delay count
pull block side 0 ; get fresh delay value
out y, 32 side 0 ; get delay count
wait_reset:
jmp y--, wait_reset side 0 ; wait until delay elapses
.wrap
@ -79,21 +80,18 @@ class NeoPixelBackground( # pylint: disable=too-few-public-methods
byte_count = bpp * n
bit_count = byte_count * 8
padding_count = byte_count % 2
padding_count = -byte_count % 4
if bit_count > 65536:
raise ValueError("Too many pixels")
# backwards, so that ulab byteswap corrects it!
header = struct.pack(">H", (bit_count - 1) & 0xFFFF)
trailer = b"\0" * padding_count + struct.pack(">H", 3840)
# backwards, so that dma byteswap corrects it!
header = struct.pack(">L", bit_count - 1)
trailer = b"\0" * padding_count + struct.pack(">L", 3840)
self._sm = StateMachine(
_program.assembled,
auto_pull=False,
first_sideset_pin=pin,
out_shift_right=False,
pull_threshold=16,
pull_threshold=32,
frequency=12_800_000,
**_program.pio_kwargs,
)
@ -128,10 +126,10 @@ class NeoPixelBackground( # pylint: disable=too-few-public-methods
def _transmit(self, buf):
if self._auto_write:
if not self._auto_writing:
self._sm.background_write(loop=memoryview(buf).cast("H"), swap=True)
self._sm.background_write(loop=memoryview(buf).cast("L"), swap=True)
self._auto_writing = True
else:
self._sm.background_write(memoryview(buf).cast("H"), swap=True)
self._sm.background_write(memoryview(buf).cast("L"), swap=True)
if __name__ == "__main__":