Faster Debugging and Firmware Flashing for PicoCalc

My Problem

I recently acquired a new PicoCalc, the latest release from Clockwork Pi. This innovative device boasts a stunning IPS screen, a responsive QWERTY keyboard, built-in speakers, and a high-capacity battery. It supports Raspberry Pi Pico models 1/1H/1W/2/2W, making it a versatile tool for developers and hobbyists alike.

While exploring the SDK and working on code development and debugging, I encountered a challenge with the recommended firmware flashing method. The official process involves using the boot select button to mount the device as a drive, then dragging and dropping the new firmware. Although this method is straightforward, it requires manually powering off the device, pressing the hard-to-reach boot select button hidden beneath the case, and then powering it back on. This repetitive process can be cumbersome and time-consuming.

Enter the Raspberry Pi Pico Probe—a cost-effective solution that offers full GDB debugging capabilities and a seamless, hands-free firmware flashing experience. In this guide, I’ll walk you through the steps to set up the Pico Probe with your PicoCalc for a smoother development workflow.

What You’ll Need

To get started, ensure you have the following items and tools ready:

Hardware

• PicoCalc: A versatile development device. Learn more about PicoCalc.
• Raspberry Pi Pico Probe: A cost-effective debugging tool that includes debug connectors. Purchase here.
• 3-Pin 2.54mm Header Pin (optional): If you’re using the Pico 1H, the default package already includes connectors, so no soldering is required.

Tools

• Small File or Cutting Pliers: For minor adjustments or trimming PicoCalc casing.
• Soldering Station (optional): Required only if you’re working with Pico models like 1/1W/2/2W that need SWD port soldering.

With these items in hand, you’ll be ready to streamline your debugging and firmware flashing process.

Setting Up Hardware

Soldering the Debug Probe (If Required)

If you’re using the default PicoCalc configuration, which includes the Pico 1H, you’re in luck—it comes pre-equipped with a debugging connector, so no soldering is necessary. However, if you’re working with other Raspberry Pi Pico models (e.g., Pico 1, 1W, 2, or 2W) that lack a pre-installed connector, you’ll need to solder a 3-pin 2.54mm header pin to enable debugging.

Modifying the Casing

To accommodate the SWD wire, you’ll need to make a small modification to the PicoCalc’s bottom casing. Use a file or cutting pliers to create a clean, precise hole. This ensures the wire can pass through without compromising the device’s aesthetics or functionality.

Clean Finish

Once the modifications are complete, you’ll have a neat and functional setup. The SWD wire will exit through the newly created hole, maintaining a tidy appearance while ensuring easy access for debugging.

Setting Up the Pico Probe

Follow the official Pico Probe documentation to install OpenOCD on your system (Windows/Linux/Mac). Once set up, the Pico Probe allows you to keep the PicoCalc powered by its battery while flashing firmware seamlessly.

Flashing Firmware

Use the following commands to flash firmware onto your PicoCalc:

For Pico 1 Models

sudo openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg -c "adapter speed 5000" -c "program hello_serial.elf verify reset exit"

For Pico 2 Models

sudo openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000" -c "program hello_serial.elf verify reset exit"

Debugging with OpenOCD and GDB

Start the OpenOCD server:

sudo openocd -f interface/cmsis-dap.cfg -f target/rp2040.cfg -c "adapter speed 5000"

In a separate terminal, navigate to your binary’s directory and attach GDB to the OpenOCD server:

gdb blink.elf
> target remote localhost:3333
> monitor reset init
> continue

Serial Debugging

The PicoCalc includes a built-in serial converter. For serial debugging, connect a USB Type-C cable directly to the PicoCalc instead of using the Pico Probe’s UART debug probe.

Conclusion

By following this guide, you can significantly enhance your PicoCalc development experience, saving time and effort while enjoying the full potential of the Pico Probe’s debugging capabilities.