RP2350B Development Board Adds RP2040 Debugging and HDMI

The RP2350B development board called Bells&Whistles puts an RP2350B target, an onboard RP2040-based debugger, an HDMI connector, and a microSD card slot onto a slim open-hardware board. The board was reported by CNX Software, and its published hardware files make it more than a closed one-off breakout.

What the RP2350B Development Board Brings Together

At the center is Raspberry Pi’s RP2350B, the larger QFN-80 variant of the RP2350 family. Raspberry Pi’s own RP2350 page lists the family’s dual Arm Cortex-M33 or dual Hazard3 RISC-V cores at 150 MHz, 520 KB of SRAM, security features built around Arm TrustZone for Cortex-M, and 12 PIO state machines. The “B” package exposes more I/O than the Pico 2-style RP2350A, which is the point here: this board breaks out up to 46 GPIO pins on two 30-pin headers.
 

Elektor has previously covered the RP2350 chip as a notable step up from the RP2040 generation. Bells&Whistles leans into that newer silicon, but also keeps one foot in the older Pico ecosystem by using an RP2040 as the debugger.

Debugging Without the Extra Dongle

The useful trick is the onboard debugger. Instead of wiring in a separate probe, the board includes an RP2040 running Picoprobe-style firmware, with SWD and UART routed internally to the main RP2350B. That gives you a cleaner setup for firmware development, serial monitoring, and quick iteration. Anyone who has lost a debug probe under a heap of jumper wires will understand the appeal.

The board also includes two USB-C ports: one for the RP2350B target and one for the debugger. Other hardware includes 4 MB of onboard SPI flash, an optional 8 MB PSRAM chip, reset and boot buttons for both microcontrollers, a user LED on GPIO46, 5 V USB power, and 3.3 V output pins. The PCB measures 87 mm × 26.5 mm, so it is longer than a Pico but still very bench-friendly.

Open Files and Familiar Software

The HDMI connector is wired for DVI-style output using GPIO12 through GPIO19, matching the pin arrangement used by the Adafruit DVI Sock and software descended from PicoDVI. That gives the board a ready software path for video experiments rather than leaving the connector as a decorative promise.

The microSD slot is connected to GPIO20 through GPIO23, making the board suitable for projects that need local storage as well as display output. The combination suggests small stand-alone interfaces, video experiments, retro-style computer projects, data loggers with local display, or teaching setups where the hardware chain should be visible but not chaotic.

Bells&Whistles is listed as a fully populated and tested PCBA on Tindie, with headers not included and optional PSRAM available. As a RP2350B development board, its main selling point is not one exotic feature, but the fact that several annoyingly separate pieces of a practical embedded workflow are already on the same PCB.