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i2c problem with Feather RP2040 and Neotrellis
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i2c problem with Feather RP2040 and Neotrellis

by hamslabs on Sat Apr 24, 2021 4:36 pm

I'm running the CPy code from the tutorial (toward the bottom of this page right after "Here is a complete example:" - https://learn.adafruit.com/adafruit-neotrellis/circuitpython-code )

I'm get this error in the serial output:
Code: Select all | TOGGLE FULL SIZE
code.py output:
Traceback (most recent call last):
  File "code.py", line 11, in <module>
RuntimeError: No pull up found on SDA or SCL; check your wiring

I've wired the Stemma QT port on the Feather to the fingers on the Neotrellis and have checked the connections. There are pull-ups on the Neotrellis so I am not sure why it is failing.

hamslabs
 
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Re: i2c problem with Feather RP2040 and Neotrellis

by hamslabs on Sat Apr 24, 2021 6:49 pm

More info:

I hooked up a QT Py to the neotrellis and ran the same code and got the same result. I also rechecked the i2c wiring and with a meter and continuity is good and there are no shorts. I also did notice that the ordering of the fingers on the edge of the board are different than the STEMMA QT connector and soldered it correctly from the start.

hamslabs
 
Posts: 6
Joined: Mon Oct 20, 2014 4:56 pm

Re: i2c problem with Feather RP2040 and Neotrellis

by hamslabs on Sun Apr 25, 2021 11:52 pm

Here is a pic of the wiring:
Screen Shot 2021-04-25 at 11.48.28 PM.png
Screen Shot 2021-04-25 at 11.48.28 PM.png (671.65 KiB) Viewed 188 times

hamslabs
 
Posts: 6
Joined: Mon Oct 20, 2014 4:56 pm

Re: i2c problem with Feather RP2040 and Neotrellis

by danhalbert on Sun Apr 25, 2021 11:59 pm

The QT Py RP2040 has a second set of pins that are used for the STEMMA connector. Do this:
Code: Select all | TOGGLE FULL SIZE
i2c = board.I2C(board.SCL1, board.SDA1)


See also the pinouts page: https://learn.adafruit.com/adafruit-qt-py-2040/pinouts

I am not sure what happened when you tried the Feather RP2040.

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Re: i2c problem with Feather RP2040 and Neotrellis

by hamslabs on Mon Apr 26, 2021 1:18 am

I'll give that a shot since I also have a QT Py RP2020. Is this also the case with the boards I already tried?

hamslabs
 
Posts: 6
Joined: Mon Oct 20, 2014 4:56 pm

Re: i2c problem with Feather RP2040 and Neotrellis

by hamslabs on Mon Apr 26, 2021 6:59 am

I hooked up a QT Py RP2040 and I get the same results.

I also tried using a different i2c board (LSM9DS1 board) and it worked so it seems that it's a problem with the NeoTrellis board. I've checked the connections and I also check that it is getting power as per the suggestion in https://github.com/adafruit/circuitpython/issues/4669

How do I initiate a return to get another board?

hamslabs
 
Posts: 6
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Re: i2c problem with Feather RP2040 and Neotrellis

by hamslabs on Mon Apr 26, 2021 8:10 am

OK this one is on me. I found a grove connector and made a cable and then removed the connector I soldered and used the cable and it works. I'm not sure what was wrong but I guess I don't need to know.

Thanks and sorry.

hamslabs
 
Posts: 6
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Re: i2c problem with Feather RP2040 and Neotrellis

by danhalbert on Mon Apr 26, 2021 8:24 am

Glad you got it working, but I am quite mystified as well. The order of the colors looks right, and your soldering looks fine. Perhaps there was a problem with the original cable, but you said you check continuity, I thought. There's always a reason. I hope it ultimately becomes clear.

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Joined: Tue Aug 08, 2017 12:37 pm

Please be positive and constructive with your questions and comments.