p9813.py

"""
MicroPython P9813 RGB LED driver
https://github.com/mcauser/micropython-p9813

MIT License
Copyright (c) 2017 Mike Causer

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

from machine import Pin
#from time import sleep_us

class P9813:
	def __init__(self, pin_clk, pin_data, num_leds):
		self.pin_clk = pin_clk
		self.pin_data = pin_data
		self.num_leds = num_leds
		self.pin_clk.init(Pin.OUT)
		self.pin_data.init(Pin.OUT)
		self.reset()

	def __setitem__(self, index, val):
		offset = index * 3
		for i in range(3):
			self.buf[offset + i] = val[i]

	def __getitem__(self, index):
		offset = index * 3
		return tuple(self.buf[offset + i] for i in range(3))

	def fill(self, color):
		for i in range(self.num_leds):
			self[i] = color

	def reset(self):
		self.buf = bytearray(self.num_leds * 3)
		# Begin data frame 4 bytes
		self._frame()
		# 4 bytes for each led (checksum, blue, green, red)
		for i in range(self.num_leds):
			self._write_byte(0xC0)
			for i in range(3):
				self._write_byte(0)
		# End data frame 4 bytes
		self._frame()

	def write(self):
		# Begin data frame 4 bytes
		self._frame()

		# 4 bytes for each led (checksum, blue, green, red)
		for i in range(self.num_leds):
			self._write_color(self.buf[i * 3], self.buf[i * 3 + 1], self.buf[i * 3 + 2])

		# End data frame 4 bytes
		self._frame()

	def _frame(self):
		# Send 32x zeros
		self.pin_data(0)
		for i in range(32):
			self._clk()

	def _clk(self):
		self.pin_clk(0)
		#sleep_us(1) # works without it
		self.pin_clk(1)
		#sleep_us(1) # works without it

	def _write_byte(self, b):
		if b == 0:
			# Fast send 8x zeros
			self.pin_data(0)
			for i in range(8):
				self._clk()
		else:
			# Send each bit, MSB first
			for i in range(8):
				if ((b & 0x80) != 0):
					self.pin_data(1)
				else:
					self.pin_data(0)
				self._clk()

				# On to the next bit
				b <<= 1

	def _write_color(self, r, g, b):
		# Send a checksum byte with the format "1 1 ~B7 ~B6 ~G7 ~G6 ~R7 ~R6"
		# The checksum colour bits should bitwise NOT the data colour bits
		checksum = 0xC0 # 0b11000000
		checksum |= (b >> 6 & 3) << 4
		checksum |= (g >> 6 & 3) << 2
		checksum |= (r >> 6 & 3)

		self._write_byte(checksum)

		# Send the 3 colours
		self._write_byte(b)
		self._write_byte(g)
		self._write_byte(r)