Commit 53145c4c authored by Jim Mussared's avatar Jim Mussared Committed by Damien George
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docs: Add docs for machine.bitstream and neopixel module.

Signed-off-by: default avatarJim Mussared <>
parent 62fd450e
......@@ -92,6 +92,7 @@ the following libraries.
......@@ -137,6 +137,28 @@ Miscellaneous functions
above. The timeout is the same for both cases and given by *timeout_us* (which
is in microseconds).
.. function:: bitstream(pin, encoding, timing, data, /)
Transmits *data* by bit-banging the specified *pin*. The *encoding* argument
specifies how the bits are encoded, and *timing* is an encoding-specific timing
The supported encodings are:
- ``0`` for "high low" pulse duration modulation. This will transmit 0 and
1 bits as timed pulses, starting with the most significant bit.
The *timing* must be a four-tuple of nanoseconds in the format
``(high_time_0, low_time_0, high_time_1, low_time_1)``. For example,
``(400, 850, 800, 450)`` is the timing specification for WS2812 RGB LEDs
at 800kHz.
The accuracy of the timing varies between ports. On Cortex M0 at 48MHz, it is
at best +/- 120ns, however on faster MCUs (ESP8266, ESP32, STM32, Pyboard), it
will be closer to +/-30ns.
.. note:: For controlling WS2812 / NeoPixel strips, see the :mod:`neopixel`
module for a higher-level API.
.. function:: rng()
Return a 24-bit software generated random number.
:mod:`neopixel` --- control of WS2812 / NeoPixel LEDs
.. module:: neopixel
:synopsis: control of WS2812 / NeoPixel LEDs
This module provides a driver for WS2818 / NeoPixel LEDs.
.. note:: This module is only included by default on the ESP8266 and ESP32
ports. On STM32 / Pyboard, you can `download the module
and copy it to the filesystem.
class NeoPixel
This class stores pixel data for a WS2812 LED strip connected to a pin. The
application should set pixel data and then call :meth:`NeoPixel.write`
when it is ready to update the strip.
For example::
import neopixel
# 32 LED strip connected to X8.
p = machine.Pin.board.X8
n = neopixel.NeoPixel(p, 32)
# Draw a red gradient.
for i in range(32):
n[i] = (i * 8, 0, 0)
# Update the strip.
.. class:: NeoPixel(pin, n, *, bpp=3, timing=1)
Construct an NeoPixel object. The parameters are:
- *pin* is a machine.Pin instance.
- *n* is the number of LEDs in the strip.
- *bpp* is 3 for RGB LEDs, and 4 for RGBW LEDs.
- *timing* is 0 for 400KHz, and 1 for 800kHz LEDs (most are 800kHz).
Pixel access methods
.. method:: NeoPixel.fill(pixel)
Sets the value of all pixels to the specified *pixel* value (i.e. an
RGB/RGBW tuple).
.. method:: NeoPixel.__len__()
Returns the number of LEDs in the strip.
.. method:: NeoPixel.__setitem__(index, val)
Set the pixel at *index* to the value, which is an RGB/RGBW tuple.
.. method:: NeoPixel.__getitem__(index)
Returns the pixel at *index* as an RGB/RGBW tuple.
Output methods
.. method:: NeoPixel.write()
Writes the current pixel data to the strip.
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