1 files changed, 84 insertions, 0 deletions
diff --git a/main.py b/main.py
new file mode 100644
index 0000000..3fa9c79
--- /dev/null
+++ b/main.py
@@ -0,0 +1,84 @@
+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()