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UedaTakeyuki / mh-z19

Read CO2 concentration from mh-z19 sensor on the Raspberry Pi & handle it. Detect Raspberry Pi model automatically and read the value from an appropriate serial device.
MIT License
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error: ubyte format requires 0 <= number <= 255 #38

Closed kzehnter closed 2 years ago

kzehnter commented 2 years ago

I have a python program which calls mh_z19.read() every few seconds and sometimes (I don't know why it is only sometimes) I get this error:

Traceback (most recent call last): File "/usr/local/lib/python2.7/dist-packages/mh_z19/init.py", line 73, in mh_z19 if len(s) >= 4 and s[0] == "\xff" and s[1] == "\x86" and checksum(s[1:-1]) == s[-1]: File "/usr/local/lib/python2.7/dist-packages/mh_z19/init.py", line 231, in checksum return struct.pack('B', 0xff - (sum(array) % 0x100) + 1) error: ubyte format requires 0 <= number <= 255

Steps to reproduce: Call mh_z19.read() every 2 seconds and wait. In an hour of runtime it happened around 4 times.

UedaTakeyuki commented 2 years ago

Thank you for your issue report, kzehnter. I think I should have cared about the case of the value of (sum(array) % 0x100)is zero.

I'll make a fix, and sorry for my late reply.

UedaTakeyuki commented 2 years ago

Happy new year, kzehnter!

I've fixed and released it as version 3.0.5.

Before fixing, this issue reproduces a few times in a thousand times. Now, not reproduce.

Would you please confirm this fix on your side? Thank you!

kzehnter commented 2 years ago

Happy new year! Thank you for fixing that so quickly! :)

I just let version 3.0.5 run on my raspberrypi for a few thousand co2 reads and I haven't gotten the error yet so I can confirm it works!

UedaTakeyuki commented 2 years ago

Hi kzehnter,

Thank you for your so quick confirmation! I've really appreciated your report giving me the opportunity to fix a bug that has been around for many years.

Would you mind if I will close this issue?