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studio8502 / Sentinel-65X

A cost-reduced 65816-compatible retrocomputer
CERN Open Hardware Licence Version 2 - Permissive
9 stars 0 forks source link

Prototype 3/4/4A review #3

Open joelpmichael opened 3 months ago

joelpmichael commented 3 months ago

As commented in #1 you should think more about your overall power supply now that you're also adding USB power, including making sure you aren't back-powering either the barrel jack (J10 in V4) or USB-VBUS if both are connected. I've used this setup successfully: TPS63000-example

The other potential issue I can see, that's been repeated over the entire design, is that connector shields are not grounds if there's ground pins inside the connector! Microchip AN2587 is a good place as any to start when diving down this infinite chasm, specifically section 12.3. The (ex-Atmel) Microchip SAM datasheets also contain an excellent schematic checklist, including a checklist item about ESD protection. The SAML21 Family Datasheet section 45.8 discusses ESD and correct grounding protection of USB connectors. This is part of the same system with the example buck-boost regulator, and includes a dedicated (yet extremely cheap because it's so common) USB ESD protection system: usb-shielding

KyleCardoza commented 3 months ago

Far as the first bit goes, there won't be a barrel jack to back-power, so no worries there. I will look at that recommended documentation, but have already fixed the shield bit, I think:

Screenshot 2024-03-08 at 1 13 24 AM

KyleCardoza commented 3 months ago

(ignore that disconnected D+ line, I just fixed it)