Gandalf/OctoPrint-Enclosure
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Fixed mistake in unpacking the data.

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Also fixed an issue with the CRC calculation. The CRC calculations need the raw bytes, not unpacked values.
This commit is contained in:
Keir Rice
2022-09-24 22:25:41 +12:00
parent f84374ca56
commit 5af13e8714
1 changed files with 12 additions and 23 deletions
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35
octoprint_enclosure/SHTC3.py
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@@ -70,18 +70,7 @@ def write_then_read(bus, address, cmd, read_length):
bus.i2c_rdwr(write, read)
return bytearray(read)
def process_crc(bytes_array):
"""Assume the last byte in the array is the CRC and check it matches the rest of the message.
Return just the message bytes."""
crc_byte = bytes_array[-1]
bytes_array = bytes_array[:-1]
if not crc_calculator.verify_checksum(bytes_array, crc_byte):
raise RuntimeError('Checksum failed')
return bytes_array
return bytes(read)
def to_relative_humidity(raw_data):
@@ -102,22 +91,22 @@ def to_temperature(raw_data):
def sample_temperature(bus, address):
send_command(bus, CMD_RESET)
send_command(bus, address, CMD_RESET)
time.sleep(0.001)
send_command(bus, CMD_WAKE)
send_command(bus, address, CMD_WAKE)
time.sleep(0.001)
try:
result = write_then_read(bus, address, CMD_NORMAL_STRETCH_T, 3)
raw_temp, crc = struct.unpack(">HI", result)
if not crc_calculator.verify_checksum(result[:-1], crc):
if not crc_calculator.verify_checksum(result[0:2], result[2]):
raise SHTC3ReadError('CRC Mismatch')
raw_temp, crc = struct.unpack(">HB", result)
return to_temperature(raw_temp)
finally:
send_command(bus, CMD_SLEEP)
send_command(bus, address, CMD_SLEEP)
def sample_humidity(bus, address):
@@ -128,11 +117,11 @@ def sample_humidity(bus, address):
try:
result = write_then_read(bus, address, CMD_NORMAL_STRETCH_RH, 3)
raw_rh, crc = struct.unpack(">HI", result)
if not crc_calculator.verify_checksum(result[:-1], crc):
if not crc_calculator.verify_checksum(result[0:2], result[2]):
raise SHTC3ReadError('CRC Mismatch')
raw_rh, crc = struct.unpack(">HB", result)
return to_relative_humidity(raw_rh)
finally:
@@ -148,14 +137,13 @@ def sample_both(bus, address):
try:
result = write_then_read(bus, address, CMD_NORMAL_STRETCH_T, 6)
raw_temp, crc_temp, raw_rh, crc_rh = struct.unpack(">HI>HI", result)
if not crc_calculator.verify_checksum(result[0:2], crc_temp):
if not crc_calculator.verify_checksum(result[0:2], result[2]):
raise SHTC3ReadError('CRC Mismatch')
if not crc_calculator.verify_checksum(result[3:5], raw_rh):
if not crc_calculator.verify_checksum(result[3:5], result[5]):
raise SHTC3ReadError('CRC Mismatch')
raw_temp, crc_temp, raw_rh, crc_rh = struct.unpack(">HBHB", result)
temperature = to_temperature(raw_temp)
humidity = to_relative_humidity(raw_rh)
@@ -177,6 +165,7 @@ def main():
try:
temperature, humidity = sample_both(bus, address)
print('{0:0.1f} | {1:0.1f}'.format(temperature, humidity))
except Exception:
print('-1 | -1')