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import glob
import time
import Adafruit_CharLCD as LCD
import Adafruit_GPIO.SPI as SPI
import Adafruit_MCP3008
def initialize_lcd():
"""Initialize LCD for usage."""
lcd_backlight = 4
lcd_rs = 25
lcd_en = 24
lcd_d4 = 23
lcd_d5 = 17
lcd_d6 = 18
lcd_d7 = 22
lcd_columns = 16
lcd_rows = 2
return LCD.Adafruit_CharLCD(
lcd_rs, lcd_en, lcd_d4, lcd_d5, lcd_d6, lcd_d7,
lcd_columns, lcd_rows, lcd_backlight)
def initialize_mcp3008():
"""Initialize mcp3008 for reading."""
SPI_PORT = 0
SPI_DEVICE = 0
return Adafruit_MCP3008.MCP3008(spi=SPI.SpiDev(SPI_PORT, SPI_DEVICE))
def get_device_file():
"""Get the path to the the data file."""
base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'
return device_file
def read_device_file(device_file):
"""Read the raw temperature from the device."""
f = open(device_file, 'r')
lines = f.readlines()
f.close()
return lines
def parse_raw_input(raw_input):
"""Parse raw data into temperatures."""
# Error reading, return nothing
if raw_input[0].strip()[-3:] != 'YES':
return None, None
equals_pos = raw_input[1].find('t=')
if equals_pos != -1:
temp_string = raw_input[1][equals_pos+2:]
temp_c = float(temp_string) / 1000.0
temp_f = temp_c * 9.0 / 5.0 + 32.0
return temp_c, temp_f
else:
return None, None
def voltage_to_moisture(data):
"""Turn adc value into percent
The value from the YL-69 can read between 0-1023 where 1023 is dry. If we
want to display the moisture percent we need to do a bit of math.
"""
val = 1024 - data
return val / 1024 * 100
def main():
"""Main routine for reading values and printing to lcd."""
lcd = initialize_lcd()
temp_device_file = get_device_file()
mcp3008 = initialize_mcp3008()
print('Writing to LCD.')
print('Press Ctrl-C to quit')
while True:
moisture = voltage_to_moisture(mcp3008.read_adc(0))
raw_temp_input = read_device_file(temp_device_file)
degrees_c, _ = parse_raw_input(raw_temp_input)
msg = "Moisture: {:.2f}\nTemp: {:.2f}".format(moisture, degrees_c)
lcd.clear()
lcd.message(msg)
time.sleep(1)
if __name__ == '__main__':
main()
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