Circuit Mashup Sanity Check?

I’m trying to get a PCB made that combines two circuits, a wireless charging receiver and a microcontroller board.

Inductive Charging Set - 5V @ 500mA max
Adafruit GEMMA M0 - Miniature wearable electronic platform

One of the challenges is that I’ve only been able to find the datasheet for the chip the receiver is based on in Japanese. But I was able to find a similar circuit on a site that used to sell a set like this, which convinces me I at least have the right reference design.

I’ve built the basic circuit using the receiver board and the Gemma, and it seems to work well, but I want to package these up to be smaller (and drop some components that I don’t need).

I’ve tried mashing up the circuits, but this is the first time I’ve designed a PCB, and I’d appreciate it if someone could look over the resulting circuit and tell me if it looks generally reasonable.

Here’s the receiver circuit reference design:


Here’s the Gemma (courtesy of GitHub - adafruit/Adafruit-Gemma-M0-PCB: PCB files for the Adafruit Gemma M0 )

Here’s my combination:


I’ve removed the battery connection and replaced it with a coil connection, removed a multicolor LED on the Gemma and replaced it with a string of LEDs, and removed the USB Mini B jack and replaced it with single pin breakouts.

Does this look generally reasonable? Do I have extraneous capacitors?

I’d also love feedback on my board design, but I’m not sure how to share that intelligibly. I designed it in Fusion Electronics.

This looks pretty good to me. The Schottky diodes will stop back feeding on either 5V bus. Coil circuit looks right by the reference design.

For power stability and filtering, it’s tough to have too many capacitors (especially when you can leave footprints unpopulated). I might even recommend a couple decoupling caps right near VDD for the SAMD21.

The only time I’ve worked with wireless power, it needed very particular capacitance for resonance tuning (way over my head), but that was aiming for Qi compatibility. By the looks of it, these parts are a lot more simple. I think you’re good.

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Thanks, @JohnWickham!

It occurred to me that I probably need a bootloader for the microcontroller. It turns out it uses three of the features that I left off of the board…

Depending on the package, you might be able to pick up an IC clip and get away with it: SOIC 8-Pin Test Clip to DIP Adapter : ID 5315 : Adafruit Industries, Unique & fun DIY electronics and kits