Wireless charging for microcontroller

[sgbaird]

A possibility for powering the microcontroller for e.g., the color sensor:

https://www.canadarobotix.com/products/2761?srsltid=AfmBOooxDHrNvKuctEIGHWXeIHusmvp-t7ae6e-OptdjdnoMbGhULSo7

https://www.adafruit.com/category/331

(https://ca.robotshop.com/products/5v-700ma-wireless-charging-pcb-module looks nice but seems to be out of stock everywhere)

Power requirements would be pretty low.

https://shop.pimoroni.com/products/pico-lipo-shim?variant=32369543086163 and (https://shop.pimoroni.com/products/lipo-battery-pack?variant=20429081991 or https://shop.pimoroni.com/products/lithium-ion-battery-pack?variant=23417820359)

Thoughts?

Related to #26

[sgbaird]

I think I'll get some of these items ordered today

[sgbaird]

@Neil-YL could you add each of the electronic components to fusion 360? If there's not an easy design file you can import, then just a basic shape with similar dimensions.

[Neil-YL]

List of files to upload:
Items on hands:

• Pico W microcontroller
• AS7341
• PiCowbell

Items to come:

• LiPo Shim (correct me if we already have one)
• Battery
• Wireless charging receiver
• Wireless charging transmitter

I think I can upload first four items today.

[sgbaird]

I think you can assume in advance that Pico W microcontroller, PiCowbell, and LiPo Shim are already soldered together (i.e., if you have the design files on hand, great, otherwise you could treat it as a box with maybe little extrusions for some of the ports)

[Neil-YL]

3D CAD files update:

• PiCowbell: (original stp file is x10 scale, scaled down to actual size)

-Alternative PiCowBell (P5905):

• Pico W: (details are slightly different)

• AS7341:

I have not found a detailed LiPo Shim board CAD model. It has a geometry of 21 x 21 x 7 mm (with the connector), may create one later with detailed connector geometry when the item is arrived.

I also made an assembled block model for the microcontroller with the PiCowbell and LiPo Shim(since it stays at the middle I do not need the detail size of it), with the largest connector on Y and X direction.

[sgbaird]

We'll also need a charger for the parking spot, and any other connections that would need to be made to attach to the transmitter. Ideally, this would be the same typical 5V charger, possibly with a female micro USB to terminal block adapter. The transmitter would need to be able to take 5V.

EDIT: Looks like the transmitter of most interest has a micro USB port and takes 5V: https://www.digikey.com/en/products/detail/adafruit-industries-llc/2162/6827104 (hence no terminal block adapter needed). However, it does specify input current of 2A, and max output of 5W:

 Technical Details o Input: 5V o Input Current: 2A o Maximum output power of 5W o Operating Frequency: 100-200kHz o Charging Distance: 2-8mm o Charging Plate Dimensions: 53mm x 53mm x 4mm / 2.1" x 2.1" x 0.2" o PCB Dimensions w/ Components: 55mm x 37mm x 6mm / 2.2" x 1.5mm x 0.2" o Weight:

The typical charger for the light mixing kit is 5V, 1A.

It seems likely that using a lower input current would just scale down the max output (down to a certain min latent current). Max output also tends to scale with distance, up to a point where it doesn't transmit at all. We would need to manually verify.

[Neil-YL]

Added a CAD model on Fusion for the assembled block with P5905

[sgbaird]

What I'm planning to get: https://www.digikey.com/short/877rfv28 (and a 5V / 2A charger)

[sgbaird]

A bunch of battery options at https://www.digikey.com/short/p9vn9dhv, but all are through Digikey.com (none available through Digikey.ca). Something 40 mAh, 150 mAh, 400 mAh, or 500 mAh would probably be enough. Even the 400 mAh isn't more than ~1.5" in the largest dimension, and the wireless receiver is ~2" in the largest dimension I think (i.e., the limiting factor).

EDIT: Needs to have the right JST connector that can plug into the Lipo shim for Pico. Kind of cool that you can estimate remaining battery power too.

[sgbaird]

@Neil-YL thoughts on https://www.digikey.ca/en/products/detail/pimoroni-ltd/PIM578/15851381 vs. the shim? EDIT: Nvm, this has an RP2040 embedded, it's not a board that gets attached to an existing Pico W (and it doesn't have wireless).