pysense: lots of invalid temp/hum values

[thomas]

Hi,

I am running the following code on a pysense board (with a LoPy):

from pysense import Pysense
from SI7006A20 import SI7006A20
import time
import pycom

pycom.heartbeat(False)
py = Pysense()
tempHum = SI7006A20(py)

for i in range(1, 100):
print("{}/{}".format(tempHum.temp(), tempHum.humidity()))
time.sleep(60)

Below is the output. It seems that most of the values are invalid. Is there any issue with my code or any known issue with the board ?

35.33643/48.2554
35.30425/174.0031
5181.098/2693.725
35.34715/16.50949
5181.088/48.24777
35.2828/2756.156
5181.077/48.27829
35.27207/47.85104
35.27207/2662.483
1260.164/174.0183
5181.152/2662.49
5181.152/2662.49
5181.077/670.1731
1260.186/47.98837
1260.164/47.76712
5181.035/2662.445

Thanks !

[bucknall]

Hi @thomas

I'm looking into this for you! Thanks for your patience!

[thomas]

Thanks @bucknall !

Please do not hesitate to get back to me if you want me to perform any test or operation on the pysense.

[bucknall]

@thomas Thanks! I'll let you know if I need any help! :)

[albert_c]

I have the same thing here!
I just received my pySense and use it out-of-the box. I upgraded my WiPy firmware to 1.7.4.1b and use the code samples from github (same as thomas above).

[albert_c]

The Problem persists after update the pySense firmware with pysense_0.0.2.dfu.

[bucknall]

Hi @albert_c,

I've made some changes to the micropython libraries which should increase stability. Could you try them again from https://github.com/pycom/pycom-libraries/tree/master/pysense and let me know if you're still having the same issues?

Thanks!

[albert_c]

I did an overnight test: no errors. Works perfectly!
Thanks a lot for the quick fix.

[bucknall]

@albert_c Fantastic! Excited to hear about what you're working on!

[albert_c]

@bucknall Currently I'm evaluating my first WiPy's / PySenses around my house and garden. I am a Geologist in Germany and work in a small company focused on environmental measurements. We always check promising new products. The PyCom product family seems like a dream come true. Easy to use, cheap, if it now turns out to be also reliable we will certainly use Pycoms for our business. I wish you success!

Btw: a great thing to have would be a MicroPython Modbus library (in case you have spare time and dont know what to do with it :-) ).

[bucknall]

@albert_c That's great to hear! We're pleased you're enjoying using our devices! :)

We have a MicroPython Modbus library on the roadmap for internal development; many people in the community have been requesting this library!

[livius]

@albert_c
As start point - here is modbus python(not micro python) lib
https://github.com/riptideio/pymodbus/tree/master/pymodbus

Maybe this can help somehow

[thomas]

Hi @bucknall,

I've just tested and it's also much better: no more errors so far. Only thing is a ~7° offset with the actual temperature. Any idea ?

Thanks anyway for the quick changes, great products, great team !

Thomas

[bucknall]

Hi @thomas,

This is expected as the temp sensor on the pysense is picking up the temperature of lopy as well. We're working on using the LoPy's internal temp sensor to use as an offset for pysense to give you the real world external temperature (One of the issues with having such a small PCB + package!).

This is in the works and should be arriving soon!

[thomas]

Ok, thanks @bucknall for the feedback.

[albert_c]

@livius
Thank you for the hint.
In fact we work with pymodbus, or I should say we use it. I'm not very deep in Modbus and new to Micropython, this is why I currently do not want to go into it deeper. But there are quite a few devices that talk modbus.

[albert_c]

@thomas, @bucknall
Thanks Thomas for checking thoroughly, thanks Bucknall for explaining the cause.

I managed reduce the offset to < 1 °C by just putting my WiPy on Break-away headers like this one.

The distance is makes clearly a difference. I did the test outdoor, without housing or enclosure, and compared to my simple outdoor thermometer. If you need exact values you certainly should elaborate more, but for my simple need +- 1° is good enough.

[mbriarg]

@bucknall Hi Alex.Do you have any librery scheduled?
Just to know if it's matter of weeks or months.

[bucknall]

Hi @mbriarg,

What are you referring to? Are you asking about the internal temperature sensor and offset that I mentioned below?

[chumelnicu]

@bucknall Hi . Any news about micropthyton mbus lib?

Thank you!