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Migrate to python3 the code #13

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Migrate to python3 the code #13

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30 changes: 15 additions & 15 deletions sht21.py
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Original file line number Diff line number Diff line change
Expand Up @@ -32,27 +32,27 @@ def __init__(self, device_number=0):
loaded). Note that this has only been tested on first revision
raspberry pi where the device_number = 0, but it should work
where device_number=1"""
self.i2c = open('/dev/i2c-%s' % device_number, 'r+', 0)
self.i2c = open('/dev/i2c-%s' % device_number, 'rb+', 0)
fcntl.ioctl(self.i2c, self.I2C_SLAVE, 0x40)
self.i2c.write(chr(self._SOFTRESET))
self.i2c.write(bytes([self._SOFTRESET]))
time.sleep(0.050)

def read_temperature(self):
"""Reads the temperature from the sensor. Not that this call blocks
for ~86ms to allow the sensor to return the data"""
self.i2c.write(chr(self._TRIGGER_TEMPERATURE_NO_HOLD))
self.i2c.write(bytes([self._TRIGGER_TEMPERATURE_NO_HOLD]))
time.sleep(self._TEMPERATURE_WAIT_TIME)
data = self.i2c.read(3)
if self._calculate_checksum(data, 2) == ord(data[2]):
if self._calculate_checksum(data, 2) == data[2]:
return self._get_temperature_from_buffer(data)

def read_humidity(self):
"""Reads the humidity from the sensor. Not that this call blocks
for ~30ms to allow the sensor to return the data"""
self.i2c.write(chr(self._TRIGGER_HUMIDITY_NO_HOLD))
self.i2c.write(bytes([self._TRIGGER_HUMIDITY_NO_HOLD]))
time.sleep(self._HUMIDITY_WAIT_TIME)
data = self.i2c.read(3)
if self._calculate_checksum(data, 2) == ord(data[2]):
if self._calculate_checksum(data, 2) == data[2]:
return self._get_humidity_from_buffer(data)

def close(self):
Expand All @@ -75,7 +75,7 @@ def _calculate_checksum(data, number_of_bytes):
crc = 0
# calculates 8-Bit checksum with given polynomial
for byteCtr in range(number_of_bytes):
crc ^= (ord(data[byteCtr]))
crc ^= data[byteCtr]
for bit in range(8, 0, -1):
if crc & 0x80:
crc = (crc << 1) ^ POLYNOMIAL
Expand All @@ -90,7 +90,7 @@ def _get_temperature_from_buffer(data):
T = -46.85 + (175.72 * (ST/2^16))
where ST is the value from the sensor
"""
unadjusted = (ord(data[0]) << 8) + ord(data[1])
unadjusted = (data[0] << 8) + data[1]
unadjusted &= SHT21._STATUS_BITS_MASK # zero the status bits
unadjusted *= 175.72
unadjusted /= 1 << 16 # divide by 2^16
Expand All @@ -104,7 +104,7 @@ def _get_humidity_from_buffer(data):
RH = -6 + (125 * (SRH / 2 ^16))
where SRH is the value read from the sensor
"""
unadjusted = (ord(data[0]) << 8) + ord(data[1])
unadjusted = (data[0] << 8) + data[1]
unadjusted &= SHT21._STATUS_BITS_MASK # zero the status bits
unadjusted *= 125.0
unadjusted /= 1 << 16 # divide by 2^16
Expand Down Expand Up @@ -134,9 +134,9 @@ def test_checksum(self):

if __name__ == "__main__":
try:
with SHT21(0) as sht21:
print "Temperature: %s" % sht21.read_temperature()
print "Humidity: %s" % sht21.read_humidity()
except IOError, e:
print e
print "Error creating connection to i2c. This must be run as root"
with SHT21(1) as sht21:
print("Temperature: %s" % sht21.read_temperature())
print("Humidity: %s" % sht21.read_humidity())
except IOError as e:
print(type(e), e)
print("Error creating connection to i2c. This must be run as root")