My SparkFun Qwiic MicroPressure Sensor stopped working and returns NAN

Sensors Force & Weight
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Continuing the discussion from SparkFun Qwiic MicroPressure sends NAN after some time:

I have followed this thread because I had the same problem. The sensor worked and then suddenly I only get NAN. My setup is simple, very short I2c cables. I only sample once a second. The library demo program also comes back with nan. Is it defective? can I get it replaced?

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What range of pressures are you working with?

Did you try to run the modified sketch from that thread?

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Sending this again as the system says I can only upload one embed.

I did not try the code because it looked like you guys were changing the library code and I don’t know how to do that. I am a fabricator with minimal coding skills so if the problem is outside my sketch or hardware I am lost.

But in any case after resting a night the sensor is working when I suck on it. It seemed to fail when I hooked it up to a vacuum pump yesterday but I will try it again tomorrow. Also maybe there is a loose wire but the display works OK and it comes after the pressure sensor in the I2c bus.

Re the pressure: thought the specs said I could go to near zero vacuum and it would be OK. My application is vacuum bagging composites so I don’t need near zero vacuum. I only need 20 hg of vacuum or even less.

I will get back to you after checking the wiring and trying the vacuum pump again.

Thanks for your time

Paul Tynan

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You probably need to disable one set of i2c pullup resistors (either on the screen or the micropressure sensor, disable by cutting the traces between the i2c pads on the MP or de-soldering the blob on the oled)

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Leave one set of them enabled.

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Ah, I forgot to mention that I read that in the Sparkfun tutorial on I2c and did that right from the start. I cut the pull up resistors on the display. I just checked the board over and resoldered any suspicious connections and it still works. It’s late so I will take it over to the vacuum pump tomorrow and see how that goes. I’ll let you know what happens.

Paul Tynan

1 Like
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OK, hooked up the thing to the vacuum pump and it is now working. Was probably my sloppy wiring. Sorry to waste your time but that “nan” message threw me off in the wrong direction.

Thanks for your time

Paul Tynan