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Python3 support in Lascar temp and humidity driver #25

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Python3 support in Lascar temp and humidity driver #25

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b030f98
Added Python 3 support
KennethNielsen Aug 9, 2019
7cb6bc2
Minor fix to keep the driver up to spec, necessary to work on Windows
KennethNielsen Aug 9, 2019
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21 changes: 14 additions & 7 deletions PyExpLabSys/drivers/lascar.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,13 +17,20 @@

from __future__ import division, print_function

import sys
import struct
try:
import hid
except (ImportError, AttributeError):
print("Cannot import hid, can be install with pip")
except SyntaxError:
print("This module makes use of hid, which is only available for Python2")


if sys.version_info.major == 3:
TEMP_START = 3
HUMIDITY_START = 2
else:
TEMP_START = '\x03'
HUMIDITY_START = '\x02'


class ElUsbRt(object):
Expand All @@ -49,24 +56,24 @@ def get_temperature_and_humidity(self):
out = {}
while len(out) < 2:
string = self.dev.read(8)
if string.startswith('\x03'):
if string[0] == TEMP_START:
frac, = struct.unpack('H', string[1:])
out['temperature'] = -200 + frac * 0.1
elif string.startswith('\x02'):
frac, = struct.unpack('B', string[1:])
elif string[0] == HUMIDITY_START:
frac, = struct.unpack('B', string[1:2])
out['humidity'] = frac * 0.5
return out

def get_temperature(self):
"""Returns the temperature (in celcius, float)"""
while True:
string = self.dev.read(8)
if string.startswith('\x03'):
if string[0] == TEMP_START:
frac, = struct.unpack('H', string[1:])
return -200 + frac * 0.1


if __name__ == '__main__':
DEV = ElUsbRt()
while True:
print(DEV.get_temperature())
print(DEV.get_temperature_and_humidity())