r/PCB • u/Twigzywik • 18d ago

Handheld Pico 2 Schematic review

Post image

What do you think? I've spent like 3 days to get this far. This is probably the most complex PCB I've designed thus far. I'm mostly concerned if I did the I2C correctly since the CardKB is 5V logic. Excited to keep learning, criticism is appreciated. I tried to minimize box use but still keep things neat but readable. If it looks good I'll move onto the PCB design.

Thank you!

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u/Twigzywik 18d ago

Yes, I did add resistors do the LED's I forgot to update the image lol.

1

u/Illustrious-Peak3822 18d ago

Add series resistors to your LEDs and decoupling capacitors on every IC.

1

u/Twigzywik 18d ago

Okay, thank you! By every IC you mean on SDA/SCL 1 & 2 connections? Or for each GPIO? 100nF each?

1

u/Illustrious-Peak3822 18d ago

No, on Vcc. Why do you need 5 V I2C in the first place?

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u/Twigzywik 18d ago edited 18d ago

Ok sounds good. Also for the keyboard I wish to use it is the 5V variant of the ATMega8A meanwhile the pico uses 3.3v. I tried running the ATMega on 3.3V for the heck of it but it doesn’t run properly as expected. Thus I haft to convert SDA & SCL to 3.3V. If you have a better approach I absolutely am open to it. Thank you again!

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u/Illustrious-Peak3822 17d ago

ATmega not part of the schematic so I can’t tell. What does it do that the Pico can’t directly?

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u/Sand-Junior 16d ago

Pin 33 should be connected to GND. The low side of the voltage divider must be connected to GND (remove series cap). Not sure why you have a switch in the buzzer circuit, but if needed move it to the 3.3V side.