RP2350 Done Framework Style

December 8, 2025 by Arya Voronova 23 Comments

Ever want a microcontroller addon for your laptops? You could do worse than match one of the new and powerful microcontrollers on the block to one of the most addon-friendly laptops, in the way the Framework RP2350 laptop card does it. Plug it in, and you get a heap of USB-connected IO coming out of the side of your laptop – what’s not to love?

The card utilizes the Framework module board space to the fullest extent possible, leaving IO expansion on SMD pads you could marry to a male or female header, your choice. With about seventeen GPIOs, power, and ground, there’s really no limit on what you could add to the side connector – maybe it’d be a logic analyzer buffer, or a breadboard cable, or a flash chip reader, maybe, even an addon to turn it into a pirate version of a Bus Pirate? There’s a fair few RP2350 peripherals available on the side header GPIOs, so sky’s the limit.

Naturally, the card is fully open-source, and even has two versions with two different USB-C plug connectors, we guess, depending on which one is better liked by your PCBA process. Want one? Just send off the files! Last time we saw an addon adding GPIOs to your laptop, it was a Pi Zero put into the optical bay of a Thinkpad, also with an expansion header available on the side – pairing yet another legendary board with a legendary laptop.

A Deep Dive Into Using PIO And DMA On The RP2350

November 30, 2025 by John Elliot V 7 Comments

Here’s a fun rabbit hole to run down if you don’t already have the RP2040/RP2350 PIO feather in your cap: how to serve data without CPU intervention using PIO and DMA on the RP2350.

If you don’t know much about the RP2040 or RP2350 here’s the basic run down: the original Raspberry Pi Pico was released in 2021 with the RP2040 at its heart, with the RP2350 making its debut in 2024 with the Pico 2. Both microcontrollers include a feature known as Programmed I/O (PIO), which lets you configure tiny state machines and other facilities (shift registers, scratch registers, FIFO buffers, etc) to process simple I/O logic, freeing up the CPU to do other tasks.

The bottom line is that you can write very simple programs to do very fast and efficient I/O and these programs can run separately to the other code running on your micro. In the video below, [piers] explains how it works and how he’s used it in his One ROM project.

This is the latest installment from [piers rocks] whose One ROM project we’ve been tracking since July this year when we first heard about it. Since then we’ve been watching this project grow up and we were there when it was only implemented on the STM32F4, when it was renamed to One ROM, and when it got its USB stack. Along the way [piers rocks] was on FLOSS Weekly Episode 850: One ROM To Rule Them All too.

Have you seen PIO being put to good use in other projects? Let us know in the comments, or on the tips line!

Continue reading “A Deep Dive Into Using PIO And DMA On The RP2350” →

LEDs That Flow: A Fluid Simulation Business Card

August 12, 2025 by Matt Varian 18 Comments

Fluid-Implicit-Particle or FLIP is a method for simulating particle interactions in fluid dynamics, commonly used in visual effects for its speed. [Nick] adapted this technique into an impressive FLIP business card.

The first thing you’ll notice about this card is its 441 LEDs arranged in a 21×21 matrix. These LEDs are controlled by an Raspberry Pi RP2350, which interfaces with a LIS2DH12TR accelerometer to detect card movement and a small 32Mb memory chip. The centerpiece is a fluid simulation where tilting the card makes the LEDs flow like water in a container. Written in Rust, the firmware implements a FLIP simulation, treating the LEDs as particles in a virtual fluid for a natural, flowing effect.

This eye-catching business card uses clever tricks to stay slim. The PCB is just 0.6mm thick—compared to the standard 1.6mm—and the 3.6mm-thick 3.7V battery sits in a cutout to distribute its width across both sides of the board. The USB-C connection for charging and programming uses clever PCB cuts, allowing the plug to slide into place as if in a dedicated connector.

Inspired by a fluid simulation pendant we previously covered, this board is just as eye-catching. Thanks to [Nick] for sharing the design files for this unique business card. Check out other fluid dynamics projects we’ve featured in the past.

Raspberry Pi RP2350 A4 Stepping Addresses E9 Current Leakage Bug

July 31, 2025 by Maya Posch 31 Comments

When Raspberry Pi’s new RP2350 MCU was released in 2024, it had a slight issue in that its GPIO pins would leak a significant amount of current when a pin is configured as input with the input buffer enabled. Known as erratum 9 (E9), it has now been addressed per the July 29 Product Change Note from Raspberry Pi for the A4 stepping along with a host of other hardware and software issues.

Although the PCN is for stepping A4, it covers both steppings A3 and A4, with the hardware fixes in A3 and only software (bootrom) fixes present in A4, as confirmed by the updated RP2350 datasheet. It tells us that A3 was an internal development stepping, ergo we should only be seeing the A4 stepping in the wild alongside the original defective A2 stepping.

When we first reported on the E9 bug it was still quite unclear what this issue was about, but nearly a month later it was officially defined as an input mode current leakage issue due to an internal pull-up that was too weak. This silicon-level issue has now finally been addressed in the A3 and thus new public A4 stepping.

Although we still have to see whether this is the end of the E9 saga, this should at least offer a way forward to those who wish to use the RP2350 MCU, but who were balking at the workarounds required for E9 such as external pull-downs.

Exploring The RP2350’s UART-Bootloader

May 11, 2025 by Tyler August 12 Comments

The RP2350 has a few advantages over its predecessor, one of which is the ability to load firmware remotely via UART, as [Thomas Pfister] has documented on his blog and in the video below.

[Thomas] had a project that needed more PWM than the RP2350 could provide, and hit upon the idea of using a second RP2350 as a port expander. Now, one could hard-code this, but dealing with two sets of firmware on one board can be annoying. That’s where the UART bootloader comes in: it will allow [Thomas] to program the port-expander RP2350 using the main microcontroller. Thus he only has to worry about one firmware, speeding up development.

Continue reading “Exploring The RP2350’s UART-Bootloader” →

Pico Pal Puts RP2350 Into Game Boy Color Shell

January 3, 2025 by Tom Nardi 14 Comments

While modern gaming systems deliver ever more realistic experiences, there’s still something to be said for the consoles and handhelds of the 80s and 90s. For many, the appeal is nostalgic. Others are attracted to the “lo-fi” graphical and sound design of these games, necessitated by the limited hardware of the time.

That said nobody would claim those old systems were perfect. Which is why a hybrid approach like [Peter Khouly] has been working on with the Pico Pal might be the ultimate solution. This replacement motherboard for the Game Boy Color (GBC) is powered by the RP2350, meaning the external hardware will have the same look and feel as it did back in 1998, but you’ll still be able to reap the benefits of modern emulation.

While the origins of the project go a bit farther, [Peter] has been working on this particular variation of the Pico Pal GBC since August, and has kept a fascinating log of his progress. Just getting the RP2350 to emulate Pokémon isn’t really that big of a deal, but getting all the ancillary hardware implemented and fitted inside the case of the GBC is a different story. Especially since [Peter] intends to pack plenty of features into the final product, such as rechargable batteries, Bluetooth audio, real-time clock support, and digital video out.

The most recent status update is from just last week, where [Peter] goes over some of the new features he’s been working on. A major one is the soft power solution, where the physical power switch doesn’t just pull the plug like it did back in the 1990s. Instead, the switch triggers the board to save the game and enter into a low-power mode so that it can come right back on to where you left off. This does impact battery life, but so far, it looks like the Pico Pal GBC will be able to run for at least five hours on a charge, and more than twice that if you don’t mind turning off the audio.

It sounds like there’s still several gremlins to track down in the design, but even in its current state, the Pico Pal GBC looks very interesting. We’re immediately reminded of the phenomenal work [Bucket Mouse] has put in on a similar refit for the original DMG-1 Game Boy.

Raspberry Pi RP2350-E9 Erratum Redefined As Input Mode Leakage Current

September 20, 2024 by Maya Posch 34 Comments

Although initially defined as an issue with GPIO inputs when configured with the internal pull-downs enabled, erratum RP2350-E9 has recently been redefined in the datasheet (page 1341) as a case of increased leakage current. As it is now understood since we previously reported, the issue occurs when a GPIO (0 – 47) is configured as input, the input buffer is enabled, and the pad voltage is somewhere between logic LOW and HIGH. In that case leakage current can be as high as 120 µA with IO_VDD = 3.3 V. This leakage current is too much for the internal pull-up to overcome, ergo the need for an external pull-down: 8.2 kΩ or less, per the erratum. Disabling the input buffer will stop the leakage current, but reading the input requires re-enabling the buffer.

GPIO Pad leakage for IOVDD=3.3 V (Credit: Raspberry Pi)

The upshot of this issue is that for input applications, the internal pull-downs are useless, and since PIO applications cannot toggle pad controls, the input buffer toggling workaround is not an option. ADC usage requires one to clear the GPIO input enable. In general any circuit that relies on floating pins or an internal pull-down resistor will be affected.

Although this should mean that the affected A2 stepping of the RP2350 MCU can still be used for applications where this is not an issue, and external pull-downs can be used as a ‘fix’ at the cost of extra power usage, it makes what should have been a drop-in replacement a troubled chip at best. At this point there have still been no definite statements from Raspberry Pi regarding a new (B0) stepping, leaving RP MCU users with the choice between the less flashy RP2040 and the buggy RP2350 for the foreseeable future.

Header: Thomas Amberg, CC BY-SA 2.0.