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#!/usr/bin/python
# Example using an RGB character LCD with PWM control of the backlight.
import math
import time
import Adafruit_CharLCD as LCD
def hsv_to_rgb(hsv):
"""Converts a tuple of hue, saturation, value to a tuple of red, green blue.
Hue should be an angle from 0.0 to 359.0. Saturation and value should be a
value from 0.0 to 1.0, where saturation controls the intensity of the hue and
value controls the brightness.
"""
# Algorithm adapted from http://www.cs.rit.edu/~ncs/color/t_convert.html
h, s, v = hsv
if s == 0:
return (v, v, v)
h /= 60.0
i = math.floor(h)
f = h-i
p = v*(1.0-s)
q = v*(1.0-s*f)
t = v*(1.0-s*(1.0-f))
if i == 0:
return (v, t, p)
elif i == 1:
return (q, v, p)
elif i == 2:
return (p, v, t)
elif i == 3:
return (p, q, v)
elif i == 4:
return (t, p, v)
else:
return (v, p, q)
# Raspberry Pi configuration:
lcd_rs = 27 # Change this to pin 21 on older revision Raspberry Pi's
lcd_en = 22
lcd_d4 = 25
lcd_d5 = 24
lcd_d6 = 23
lcd_d7 = 18
lcd_red = 4
lcd_green = 17
lcd_blue = 7 # Pin 7 is CE1
# BeagleBone Black configuration:
# lcd_rs = 'P8_8'
# lcd_en = 'P8_10'
# lcd_d4 = 'P8_18'
# lcd_d5 = 'P8_16'
# lcd_d6 = 'P8_14'
# lcd_d7 = 'P8_12'
# lcd_red = 'P9_16'
# lcd_green = 'P9_14'
# lcd_blue = 'P8_13'
# Define LCD column and row size for 16x2 LCD.
lcd_columns = 16
lcd_rows = 2
# Alternatively specify a 20x4 LCD.
# lcd_columns = 20
# lcd_rows = 4
# Initialize the LCD using the pins
lcd = LCD.Adafruit_RGBCharLCD(lcd_rs, lcd_en, lcd_d4, lcd_d5, lcd_d6, lcd_d7,
lcd_columns, lcd_rows, lcd_red, lcd_green, lcd_blue,
enable_pwm=True)
# Show some basic colors.
lcd.set_color(1.0, 0.0, 0.0)
lcd.clear()
lcd.message('RED')
time.sleep(3.0)
lcd.set_color(0.0, 1.0, 0.0)
lcd.clear()
lcd.message('GREEN')
time.sleep(3.0)
lcd.set_color(0.0, 0.0, 1.0)
lcd.clear()
lcd.message('BLUE')
time.sleep(3.0)
lcd.set_color(1.0, 1.0, 0.0)
lcd.clear()
lcd.message('YELLOW')
time.sleep(3.0)
lcd.set_color(0.0, 1.0, 1.0)
lcd.clear()
lcd.message('CYAN')
time.sleep(3.0)
lcd.set_color(1.0, 0.0, 1.0)
lcd.clear()
lcd.message('MAGENTA')
time.sleep(3.0)
lcd.set_color(1.0, 1.0, 1.0)
lcd.clear()
lcd.message('WHITE')
time.sleep(3.0)
# Use HSV color space so the hue can be adjusted to see a nice gradient of colors.
# Hue ranges from 0.0 to 359.0, saturation from 0.0 to 1.0, and value from 0.0 to 1.0.
hue = 0.0
saturation = 1.0
value = 1.0
# Loop through all RGB colors.
lcd.clear()
print('Press Ctrl-C to quit.')
while True:
# Convert HSV to RGB colors.
red, green, blue = hsv_to_rgb((hue, saturation, value))
# Set backlight color.
lcd.set_color(red, green, blue)
# Print message with RGB values to display.
lcd.set_cursor(0, 0)
lcd.message('RED GREEN BLUE\n{0:0.2f} {1:0.2f} {2:0.2f}'.format(red, green, blue))
# Increment hue (wrapping around at 360 degrees).
hue += 1.0
if hue > 359.0:
hue = 0.0
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