NFTy GIFty Schematic Review (for a holiday ornament style PCB)

RE: NFTy GIFty Schematic Review (for a holiday ornament style PCB)

dang74 — Tue, 08 Nov 2022 14:19:14 GMT

This is a pretty interesting project. Even beyond the specific NFTy GIFty, which is clever by the way, this project can serve as a template for anyone wanting to make a display with slide show capabilities.

RE: NFTy GIFty Schematic Review (for a holiday ornament style PCB)

shabaz — Tue, 08 Nov 2022 02:05:56 GMT

Looking forward to seeing the project develop!

I was wondering, what is U4, is that a typo, should it be a switch (e.g. SW4) instead of being labeled U4, or is it a power switch IC?

If it's a mechanical switch, then there could be a possibility of it being in the Vbatt position when the user has also plugged in the USB connector on the Pico, and in that case, VSYS may be at about 4.3-4.4V or so, from the USB power.
To prevent that, the Pico datasheet suggests either a diode, or a MOSFET. I've been using a MOSFET so far for most Pico projects, like this (where VSW in this screenshot would be Vbatt in your project), which is just a slight elaboration on what the datasheet mentions (I added the R16 in the screenshot so it's in a known state, it might not be necessary but just-in-case, and R15 since the gate is so tiny, I wonder if it may accidentally damage it over time if I don't):

RE: NFTy GIFty Schematic Review (for a holiday ornament style PCB)

wolfgangfriedrich — Mon, 07 Nov 2022 18:57:28 GMT

Merry Christmas, @baldengineer [emoticon:7d1c30a529784d14beaf7b38c0b9ab88]

1)The backlight looks very dim with the 47R resistor and 3.3V or 3.7V feed. At 80mA the nominal voltage drop would be >3.3V already ( 0.08A * 47R ).

2) I always add a 22R series resistor to clock lines (SCLK_SD, SCLK), just for good measure. Don't want to set your tree on flames with too much EMI. ;)

3) I am not a fan of the GND net only connection on the PiPico pins, but that is personal preference only.

4) And the trace from R1 to pin 35 can never work with so many right angles on it.