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ledstrip.py
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ledstrip.py
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import numpy as np
import os.path
_gamma = np.load(os.path.join(os.path.dirname(__file__), 'gamma_table.npy'))
## wireformat:
## [16 bit: led address][8 bit Red][8 bit Blue][8 bit Green] == 40bit
def decode_pos(left, right):
return (ord(left) << 8) | ord(right)
def encode_pos(pos):
return chr((pos >> 8 ) & 0xff) + chr(pos & 0xff)
previous_state = None
def update_strip(pixels, socket):
global previous_state
# pixels is a numpy ndarray of dimension (3, 900), with 8bit R, G, and B values
# for each of the (hardcoded) 900 LEDs. The wireformat addresses the leds by their
# integer address from 0-899. See https://www.pjrc.com/teensy/td_libs_OctoWS2811.html for
# details on the addressing scheme
bytes_per_pixel = 5 # 2x for address + 3x1 for RGB
max_payload = 30 # send max 30 leds per serial send
pixels = np.clip(pixels, 0, 255).astype(int)
# Optionally apply gamma correc tio
#pixels = _gamma[pixels]
# packet is what is sent over the serial to the teensy
packet = ''
for i in range(900):
if previous_state is not None and np.array_equal(pixels[:, i], previous_state[:, i]):
# nothing changed on that pixel, continue
continue
packet += encode_pos(i) + chr(pixels[0][i]) + chr(pixels[1][i]) + chr(pixels[2][i])
if (len(packet)/bytes_per_pixel) + 1 > max_payload:
socket.write(packet)
packet = ''
if packet:
# send the rest
socket.write(packet)
previous_state = np.copy(pixels)
# receives numpy arrays, convertes them into the searial wireformat and sends it over serial
class MockSerial(object):
def write(self, packet):
#print 'received packet', len(packet), list(packet)
step = 5 #bytes per pixel
for i in range(0, len(packet), step):
pos = decode_pos(packet[i:i+1], packet[i+1:i+2])
r, g, b = [ord(val) for val in packet[i+2:i+step]]
print 'setting pixel <{}> to ({} {} {})'.format(pos, r, g, b)
def close(self):
pass