In this video I aim to set a cat amongst the pigeons by revealing 5 ways that I found the STM32F4 microcontroller better for powering One ROM than Raspberry Pi’s RP2350 (A4 stepping).

There’s also a sneak preview of the new 28 pin One ROM prototype.

Those reasons are:

  1. Boot time The STM32F4’s boot time is 10x faster than the RP2350’s (STM32F4 1.5ms vs RP2350 15ms)
  2. Faster The STM32F4 achieves better performance at lower clock speeds than the RP2350 (C64 KERNAL emulation, STM32F4 80MHz vs RP2350 90MHz)
  3. PCB Layout The STM32F4 is much easier to lay out on a space constrained 2 layer PCB than the RP2350
  4. 5V Tolerance The STM32F4 is more robust to 5V, and higher voltages, than the RP2350
  5. Assembly The RP2350 is more prone to assembly mistakes than the STM32F4 (LQFP package)

As mentioned in this week’s video, I was interviewed by Hackaday for their FLOSS (Free Libre Open Source Software) Weekly podcast last week. Link below.

🔗 Links

Hackaday’s FLOSS Weekly Podcast: https://piers.rocks/2025/10/09/floss-weekly.html
Blog post describing RP2350 One ROM finding: https://piers.rocks/2025/08/25/rp2350-5v-gpios.html
One ROM RP2350 Deep Dive: https://youtu.be/Zy8IMe6fMI4
One ROM website: https://onerom.org/

🛒 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/

Don’t feel you need to buy my version of One ROM - I have no problem with you getting them fabbed yourself, or even selling them for profit. I will even advertise your version of One ROM on my youtube channel and at onerom.org if you share a link with me.

⏰ Timestamps

00:00 🎬 Introduction
00:50 📖 Comparing parts
01:44 🚀 Reason 1 - Boot Time
03:02 ⚡ Reason 2 - Faster
04:36 📐 Reason 3 - PCB Layout
06:18 ⚠️ Reason 4 - 5V Tolerance
09:07 🔧 Reason 5 - Assembly
11:26 👀 28 pin One ROM
12:12 💭 Final thoughts

Video content copyright (c) 2025 piers.media Limited. All rights reserved.

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