This 28 pin One ROM RP2350 layout nearly broke me

In this video I nearly met my match, laying out a 28 pin version of One ROM Fire using the RP2350 microcontroller.

I stuck to a 2 layer PCB to keep costs low, and the additional address and CS lines needed, combined with adding a USB-C connector to an already constrained layout, made this an even bigger challenge than the 24 pin version.

🔗 Links

One ROM website: https://onerom.org/
24 pin layout: https://youtu.be/xIey26uy0MU
PIO/DMA algorithm: https://youtu.be/Y8RODQZM2HY

🛒 Buy One ROMs

Keep an eye on my online store if you want to buy One ROMs when they are available:

https://www.packom.net/product/one-rom/

If you sell a version of One ROM, let me know so I can publicise it on youtube and at https://onerom.org/

⏰ Timestamps

00:00:00 🎬 Introduction
00:03:01 📐 Existing 24 pin layout
00:06:00 💾 28 pin ROM types
00:10:14 🔧 Schematic updates
00:14:01 🔌 USB-C connector
00:23:01 🎨 New layout
01:26:46 ⚠️ USB layout error
01:27:56 ⚡ Schottky diode replacement
01:30:55 🛒 Ordering
01:35:45 💭 Final thoughts