I recently bought a Grove Shield for Wio Lite hoping to use it with my Particle Mesh devices and some Grove sensors that I have. On the website it was mentioned that the Shield should support Particle Mesh: https://blog.adafruit.com/2019/08/26/new-product-grove-shield-featherwing-for-all-feathers-wio-lite/ and indeed they do have compatible pinouts.
However, when I plug my Particle Xenon into Shield and in usb power, no LEDs are live on the Xenon itself, only green LED on the Shield is live. Also, Xenon does not appear to be live in the Particle Cloud.
There is a switch on the side of the Shield which is meant to switch power to/from battery. Changing the switch position does not help.
If I unplug the Xenon from the Shield, I can get it to come live in the Particle Cloud again.
Does anyone tried this Shield or know if it is compatible? What can I do to troubleshoot?
Does the Xenon work when not plugged into the shield?
Can you check the voltage on the EN pin of the Xenon?
As it seems the respective pin in the shield is marked GND and if that is in deed connected to GND, that would explain the behaviour.
You could try cutting the thermals (traces between the centrals solder pad and the GND plane) on both headers and hope there are no other connections pulling EN low.
I would say the EN-pin is pulled to GND because there’s a buck-converter onboard and EN disables the supply of the feather boards.
So the Xenon should get the 3.3V from that regulator.
But I just tried it, my Xenon also doesn’t do anything when powering it from external 3.3V …
The buck convertor takes the 5v (or batt V depending on the switch) and reduces it to 3V3 for the periphery 3V3 grove devices. The Xenon does not have a 3V3 input - only the 5V and LiPo. So the EN low disables the onboard 3V3 regulator and therefore the device will not startup.
You need perhaps open a support ticket with Adafruit?
If this is not going to work for you, you could also bend the EN pin on the xenon out to the side - ( Do this only at your own risk and it is only my personal suggestion - This will possibly invalidate your warranty ) and reinsert into the Grove shield as a test.
I‘d rather modify the Grove-board since it’s cheaper and you could use it with other boards.
The regulator on the shield should also be disabled .
Not exactly what compatibly means to me …
Don’t disable the shield regulator - otherwise the grove connected peripherals won’t function - the 3V3 out of the Xenon does not seem to be connected to anywhere else except the two headers.
Looks like you’re right, but in that case it doesn’t make sense that the feather’s internal regulator is disabled by pulling EN low because it will not be powered by any source
Edit: According to the pictures, there leads a trace from the 3.3v-pins somewhere, it’s just a bit difficult to follow it because it changes layers.
I have used dozens of those boards with particle devices , the one in question is the Grove Shield for Wio Lite, Which I just purchased yesterday from Adafriut and is indeed not compatible with Particle Mesh
I think (what should be) the EN pin is connected to top and bottom ground planes; I tried removing the whole annular ring on the bottom and still read a short to ground with the DMM. We drilled out the whole pin and it’s working now.
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