REVIEW: PICOPROBE PCB KIT 1.0 👎🏻

I haven’t been using a Picoprobe for a while because I needed to rebuild mine and issues with the code’s dependencies and a lack of updates from the Raspberry Pi Foundation meant I haven’t been able to get it to work properly. But I did spot this doohickey: a PCB you can solder a Pico and a header. It’s a much neater way to assemble a Picoprobe than breadboard and jumper wires.

Streamline your Picoprobe setup into a single, slim board

And, at £9, it’s not expensive. But it is flawed, so I suggest caution before rushing to buy one.

The PCB, as you can, takes a Pico. You can solder it directly to the PCB—I did this—or fit suitable header and then just clip the Pico on. The PCB comes with sets of male and female header for the business end: the feed from the GPIO pins through which the Pico—running the Picoprobe software—operates as a USB-to-SWD bridge.

In addition, the PCB ships with a JTAG header and cable, a connector more familiar to embedded engineers.

The business end’s pin names are inconveniently on the underside

The Pico’s GPIOs 2, 3 are routed to the SWD IO and CLK output, as is a GND pin—you connect these pins to the SDWIO, SWDCLK and GND pins on your test Pico at the opposite end to the USB port.

GPIO 4 and 5 are routed to the PCB header’s SWO and RESET pins—despite the name these are the Picoprobe’s stdio UART pins.

The board traces: left is the upper side of the PCB, right the underside (Pic: Pimoroni)

What the PCB doesn’t have—and this, for me, is the killer—is 3V3 output. There’s a header marked VREF—you can see it in the pics above—but it’s connected to GPIO 28. Did the designer mean to connect the header pin to the Pico’s ADC-VREF pin, which is the next one along? Possibly, but it’s still not a 3V3 output that you can use to power the test Pico. That’s the next one along.

So you can’t power your test Pico from a PCB-mounted Pico, at least not without adding extra wiring, and that kind of defeats the product’s purpose.

Nice idea—shame about the beta-release implementation. I say wait for version 2.0.

Picoprobe connected to host

The Picoprobe PCB Kit is available from Pirmoroni and other Pico-friendly retailers.

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