Bela Gem Multi stopped working all of the sudden.

Mac_Tire

Thanks for the explanation Giulio. I am understanding that I made a mistake, but I have some question regarding what you wrote.
If I want to plug the Bela Gem Multi to a PCB of my own design removing the two audio wings, attaching the Bela from the J6, J8, J9, J3, J10, J11 and J7 directly to my PCB, which connection I need to use to power up both the Bela and the PocketBeagle2?

I am getting confused because the system has worked until yesterday. And in the last week the only source of power for the Bela Gem and the PocketBeagle2 was my main PCB through the connection I indicated in my previous message.

I specify again that this project has been going on for the last three months and in the last two the Bela has always worked and be powered up by my main PCB.

giuliomoro

Mac_Tire which connection I need to use to power up both the Bela and the PocketBeagle2?

Quoted from above:

To power the board when a USB-C power source is not available, VBAT should be used for LiPo cells and VIN_5V should be used for any other power source, except as noted below.

VIN_5V is P1.01. So that's the short answer. However, you likely have an A4 board, so if you need to use the USB host port while powered from your power supply, you should instead use a low-dropout diode from your power supply into USB_VBUS (P1.07) instead.

giuliomoro

Mac_Tire I am getting confused because the system has worked until yesterday. And in the last week the only source of power for the Bela Gem and the PocketBeagle2 was my main PCB through the connection I indicated in my previous message.

I specify again that this project has been going on for the last three months and in the last two the Bela has always worked and be powered up by my main PCB.

Yes, that's puzzling for me as well. I am not sure exactly what may have gone wrong there, but the fact that you had the two supplies fighting each other may have played a role in that. For there to be any trouble, USB_5V (coming from USB-C) had to be slightly higher than your 5V supply, and I see how those voltages may not be constant over time, so that the condition would not be true all the time.

Mac_Tire

Ok Giulio, thanks for the explanation. I am more and more convinced that I fried the PocketBeagle2. Just some more question before risking to damage another board. I just connected the Bela Gem Multi, without the PocketBeagle2, to the PCB I designed. The connection is made through the female header I indicated you before and it power up as usual. This is puzzling me, because if you said that the 5V on J8 and J10 are outputs, how is it possibile that the board is powering up? Through my PCB the Bela Gem Multi is receiving both 5V e 3.3V on J8 and the 5V line is connected also to J10. If those connection are output they shouldn't power up the board, right?

giuliomoro

Mac_Tire is is puzzling me, because if you said that the 5V on J8 and J10 are outputs,

They are outputs from the PB2, which are used (as inputs) by the Gem cape. What do you mean the board "is powering up"?

Mac_Tire Through my PCB the Bela Gem Multi is receiving both 5V e 3.3V on J8 and the 5V line is connected also to J10.

Wait you are also providing 3.3V??? That's a no-no. Those are generated on the PB2 and are output on the 3v3 pins. There's no diodes there, so providing 3.3V externally has an even higher chance to break things than the 5V thing discussed above. The only way you can have them generated from your power supply and not break things is to remove the 3.3V pins that go from the Gem cape into the PocketBeagle 2, but I don't recommend doing that. Just use the 3.3V from the PB2 as a source and do not provide your own.

Mac_Tire

And another question, in this scenario you think that the damage was only on the PocketBeagle2 or also the Bela Gem Multi could have been damaged since I was feeding 5V on an output connection instead that on a input connection?

giuliomoro

Mac_Tire in this scenario you think that the damage was only on the PocketBeagle2 or also the Bela Gem Multi could have been damaged since I was feeding 5V on an output connection instead that on a input connection?

I would expect only the PB2 to have been damaged.

Mac_Tire

giuliomoro They are outputs from the PB2, which are used (as inputs) by the Gem cape. What do you mean the board "is powering up"?

I mean that if I plug the Gem cape on my PCB the led on the Gem cape turns on.

giuliomoro Wait you are also providing 3.3V??? That's a no-no. Those are generated on the PB2 and are output on the 3v3 pins. There's no diodes there, so providing 3.3V externally has an even higher chance to break things than the 5V thing discussed above. The only way you can have them generated from your power supply and not break things is to remove the 3.3V pins that go from the Gem cape into the PocketBeagle 2, but I don't recommend doing that. Just use the 3.3V from the PB2 as a source and do not provide your own.

Ok. I made a huge mistake then. I don't even know how it is possible that it worked for so long. I'll buy a new pocket beagle to check and hope that the Gem cape didn't suffered from any power up issue.
Thanks for all the help Giulio!

Mac_Tire

Just another question. Since I am using the i2c connection on this design, the components on my PCB can work with the 3.3V coming from the i2c connection? I would like to clarify everything so that I can go on without any more mistakes like these.

giuliomoro

Mac_Tire the components on my PCB can work with the 3.3V coming from the i2c connection?

Yes. You can use a different 3.3V for them, just connect the two GND together in that case, and do not connect the two 3.3V together. Pullups (if you need to add more than what's already on board) can go to either 3.3V source.

Mac_Tire

giuliomoro Yes. You can use a different 3.3V for them, just connect the two GND together in that case, and do not connect the two 3.3V together. Pullups (if you need to add more than what's already on board) can go to either 3.3V source.

Ok Giulio, thanks for the support and help. I have a clear idea on how to work with everything now. I probably should have asked you before starting. But, that is knowledge and learning one way or another.

giuliomoro I would expect only the PB2 to have been damaged.

I hope so! I'm gonna order another PocketBeagle2 right away from Mouser and let you know if the Gem Cape works fine. In case it doesn't I'll order another cape from the Bela website.

giuliomoro

Mac_Tire In case it doesn't I'll order another cape from the Bela website.

They are on Mouser as well now, in case that ends up being cheaper for you.

Mac_Tire

giuliomoro
Oh, I didn't know that! Thanks for the tip

giuliomoro

https://www2.mouser.com/ProductDetail/Bela/160802-BELA-GEM-MULTI?qs=4dK74SdgGtxAw8RDBR0KOA%3D%3D and https://www2.mouser.com/ProductDetail/Bela/160801-BELA-GEM-STEREO?qs=4dK74SdgGtz2j7Gxphb2JQ%3D%3D&_gl=1*ylfmvy*_ga*dW5kZWZpbmVk*_ga_15W4STQT4T*dW5kZWZpbmVk*_ga_1KQLCYKRX3*dW5kZWZpbmVk

The Multi is mistakenly indicated as "End of life". We are trying to get them to fix that.

Mac_Tire

Ok, thanks also for the links. Cannot wait to solve these errors I made so that I can continue with the project!

Mac_Tire

Hi Giulio! The new PocketBeagle2 arrived and the Bela cape is working fine. Just a final check with you before proceeding with the rework of my project.
Can I access the P1.01. on the PocketBeagle2, to power it up with a 5V signal, using the P1 input on the Bela cape right?
I checked the Cape Header Connectors page of the PocketBeagle2 manual, and I also checked on the Bela cape with a multimeter, but I want to be extra sure that the P1 on the Bela cape goes just to the P1.01. on the PocketBeagle2.

Thanks again for all the support!

giuliomoro

Mac_Tire Can I access the P1.01. on the PocketBeagle2, to power it up with a 5V signal, using the P1 input on the Bela cape right?

Yes, correct

Mac_Tire

giuliomoro
Amazing! Thanks for the confirmation!