import smbus
import time
try:
import struct
except ImportError:
import ustruct as struct
class AM2320Exception(Exception):
""" Base class for exception """
class AM2320DeviceNotFound(AM2320Exception, ValueError):
""" Device not found """
class AM2320ReadError(AM2320Exception, RuntimeError):
""" Read error or CRC mismatch """
def _crc16(data):
crc = 0xFFFF
for byte in data:
crc ^= byte
for _ in range(8):
if crc & 0x0001:
crc >>= 1
crc ^= 0xA001
else:
crc >>= 1
return crc
sensor = smbus.SMBus(1)
def getTemp(bus):
for _ in range(3):
try:
bus.write_byte(0x5C, 0x00)
except:
pass
bus.write_i2c_block_data(0x5C, 0x03, [0x02, 2])
time.sleep(0.001)
result = bytearray(bus.read_i2c_block_data(0x5C, 0x00, 6))
if result[0] != 0x3 or result[1] != 2:
raise AM2320ReadError("Command does not match returned data")
temp = struct.unpack(">H", result[2:-2])[0]
crc1 = struct.unpack("<H", bytes(result[-2:]))[0]
crc2 = _crc16(result[0:-2])
if crc1 != crc2:
raise AM2320ReadError("CRC Mismatch")
if temp >= 32768:
temp = 32768 - temp
return (temp / 10.0)
def getHumi(bus):
for _ in range(3):
try:
bus.write_byte(0x5C, 0x00)
except:
pass
bus.write_i2c_block_data(0x5C, 0x03, [0x00, 2])
time.sleep(0.001)
result = bytearray(bus.read_i2c_block_data(0x5C, 0x00, 6))
if result[0] != 0x3 or result[1] != 2:
raise AM2320ReadError("Command does not match returned data")
humi = struct.unpack(">H", result[2:-2])[0]
crc1 = struct.unpack("<H", bytes(result[-2:]))[0]
crc2 = _crc16(result[0:-2])
if crc1 != crc2:
raise AM2320ReadError("CRC Mismatch")
return (humi / 10.0)
def main():
try:
temperature = getTemp(sensor)
humidity = getHumi(sensor)
print('{0:0.1f} | {1:0.1f}'.format(temperature, humidity))
except:
print('-1 | -1')
if __name__ == "__main__":
main()
