Adafruit Ht16k33 backpacks

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n00dle
 
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Joined: Thu Feb 16, 2023 5:02 pm

Adafruit Ht16k33 backpacks

Post by n00dle »

Hi guys,
Random little issue I just can't figure out. I have some HT16K33 backpacks from adafruit, which when connected to a nano via i2c (pins a4 and a5) they do not work and running the i2c scanner just hangs.

If i plug the backpack into an Uno, they work just fine and i2c scanner shows the correct address.

I thought it might be an issue with the nano but if i plug in an i2c display it works just fine and the i2c scanner finds the address of the display no problem.

I have 4 of these backpacks and they all work on the uno but dont on the nano!? i have also tried three other nano's and all have the same result ... they can find and run the display but won't find any of the ht16k33 backpacks???

I’ve also tried plugging the display and the backpack into the nano joining the scl/sda wires and the scanner runs but only finds the display, as soon as I disconnect the display the scanner hangs.

And lastly, I ran the scanner on an uno and plugged the sda/scl wires from the backpack into it, then rand the 5v & ground into the backpack from the nano and it ran fine so it can’t be a nano power issue?

The nanos are the 5v 16Mhz version, and all work with other scripts etc. it’s just something about these backpacks.

Any ideas as I've spent hours googling and have come up empty!?

Cheers

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adafruit_support_mike
 
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Re: Adafruit Ht16k33 backpacks

Post by adafruit_support_mike »

Try adding 4.7k pull-up resistors on the SDA and SCL lines.

The HT16K33 breakout has 10k pull-ups, but the Nano may need something a bit stronger.

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n00dle
 
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Re: Adafruit Ht16k33 backpacks

Post by n00dle »

Thanks, I’ll give it a try!

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