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Get started with the pic0rick

This guide takes you from an unboxed pic0rick to your first ultrasound acquisition. No prior ultrasound or embedded systems experience is required.

Step 1: What you need

Before you begin, make sure you have the following:

Item Notes
pic0rick main board Available on Tindie or build from KiCad sources
Pulser board Connects via the single PMOD header — generates the transmit pulse
HV board Generates +-25V for the pulser. Plugs into the pulser board
A single-element ultrasound transducer Any single-element probe in the 1–10 MHz range will work. See compatible probes for suggestions
SMA cable To connect the transducer to the board’s receive SMA connector
SMA connectors Coax connectors for both the pulser and the AFE boards, where to connect your cables
2.54 connectors The 2.54mm usual headers, I use them 90° angle as you can see below, female on the AFE board, male on the PMOD smaller boards
rp2350/rp2040 THe usual form factor, to assemble the board and get your microcontroler of choice
USB cable For power and data connection to your computer
A computer Any OS with Python 3 installed (Windows, macOS, Linux)
A test target (optional) A glass of water with a coin at the bottom, a metal block, or any solid object for reflection testing

The assembled stack

The three boards connect together like this: HV board → Pulser board → pic0rick main board (via the single PMOD header). The double PMOD header on the other side can optionally connect to a VGA output or MUX extension.

Assembled pic0rick

Step 2: Flash the firmware

The pic0rick uses an RP2040 microcontroller, which appears as a USB mass storage device when put into boot mode.

  1. Enter boot mode: Hold the BOOTSEL button on the pic0rick board while plugging in the USB cable. The board should appear as a USB drive named RPI-RP2.
  2. Copy the firmware: Download the latest .uf2 firmware file from the pic0rick releases page and drag it onto the RPI-RP2 drive.
  3. Wait for reboot: The board will automatically reboot once the file is copied. The USB drive will disappear — this is normal.

If you prefer to build from source, the firmware code is in the pic0rick repository under the software/ directory.

Step 3: Connect the transducer

  1. Connect your single-element transducer to the Receive SMA connector on the pic0rick main board using an SMA cable.
  2. Point the transducer at your test target. For a simple first test, press the transducer against a flat metal surface or immerse it in a glass of water aimed at the bottom.
  3. Make sure the HV board and pulser board are connected and the full stack is powered via USB.

Step 4: Install the software

The pic0rick communicates over USB serial. You need Python 3 and a few libraries.

pip install pyserial numpy matplotlib

Clone the software repository:

git clone https://github.com/kelu124/pic0rick.git
cd pic0rick/software

Step 5: Your first acquisition

Run the acquisition script to capture your first ultrasound echo:

python pico_shell.py

This script connects to the pic0rick over serial, triggers a pulse, and captures the reflected signal through the ADC. You should see a waveform plot showing the initial pulse and any echoes from your test target.

What you should see

A typical acquisition looks like this — the large spike on the left is the transmit pulse, and the smaller peaks to the right are reflections from your target:

Example acquisition

Adjusting the gain

The pic0rick features a Time-Gain Compensation (TGC) system using an AD8331 amplifier (7.5 dB to 55.5 dB range), controlled via an MCP4812 SPI DAC. You can adjust the gain curve in your acquisition script to compensate for signal attenuation at depth. The gain setting in the example above is set to 6 — try different values to see how they affect the signal.

Step 6: What’s next?

Now that you have your first acquisition working, here are some directions to explore:

Troubleshooting

Board not detected over USB

  • Make sure you are using a data-capable USB-C cable (some cables are charge-only).
  • Try a different USB port. Some hubs may not provide enough power.
  • Check that the firmware was flashed correctly — re-enter boot mode and re-flash the .uf2 file.

No echo signal visible

  • Check the SMA cable connection — make sure the transducer is firmly connected.
  • Verify the pulser and HV boards are connected and powered. The pulser needs the HV board to generate transmit pulses.
  • Try a simpler target: press the transducer flat against a thick metal plate. You should see a strong back-wall echo.
  • Increase the gain setting in your acquisition script.

Signal looks very noisy

  • Make sure the HV board is properly seated on the pulser board. Loose connections introduce noise.
  • Keep the USB cable and SMA cable separated — they can couple electromagnetically.
  • Try averaging multiple acquisitions to improve the signal-to-noise ratio.
  • If using a breadboard or loose wires for any connections, switch to direct board-to-board connections.

Serial port permission issues (Linux)

On Linux, you may need to add your user to the dialout group:

sudo usermod -aG dialout $USER

Then log out and back in for the change to take effect.

Going deeper