Ultr4rick

ultr4rick

Ultr4rick is an open ultrasound pulse-echo board, the higher-power successor to pic0rick. It is built around an RP2350B and has:

• a 10-bit, 60 MS/s ADC (AD9215) behind an AD8331 variable-gain front end, with gain set by an MCP4812 DAC;
• a bipolar HV pulser driven by two logic lines (A = negative, B = positive, A+B = damping), fed by a SEPIC HV supply;
• a MAX14866 16-channel HV mux;
• a uSD slot, an LP5562 RGB LED driver on I2C, and USB.

The firmware can compute the Hilbert envelope (and A-law compression) of each 4096-sample capture on the board.

The board

Front. HV supply, pulser, RP2350B and receive front end (AFE). PULSER_OUT and AFE_IN SMA connectors on the right edge, USB-C and uSD on the left.	Back. The MAX14866 HV mux and the 8 U.FL element connectors (U18–U21, U26–U29).
Running. Powered over USB-C (about 0.96 W on the inline meter), with one transducer on PULSER_OUT and AFE_IN through an SMA tee.

The KiCad renders are in hardware/Ultr4rick_F.png and hardware/Ultr4rick_B.png. The photos are described in docs/images/README.md.

Acquisition examples

Pulse-echo on the mux: each element in turn on TX and RX with set_one_mux(k), raw ADC trace (top) and on-board Hilbert envelope (bottom). Elements 2 and 4 show echo trains: about every 13 µs on element 2 and every 20 µs on element 4. From python/example_dsp.ipynb, section 13.

Idle vs. pulsed capture at gain 50, pulse 96/6000/96 ns: the excitation at 0.9 µs, the receiver recovering until about 6 µs, and the envelope computed on the board. From python/example_dsp.ipynb, section 15.

Repository layout

Quick start

Build the firmware (Pico SDK 2.3.0, arm-none-eabi-gcc, CMake + Ninja):

cd firmware
export PICO_SDK_PATH=$HOME/.pico-sdk/sdk/2.3.0
./build.sh -DPICO_TOOLCHAIN_PATH=/usr
# dist/ultr4rick-v<ver>-ultr4rick.uf2      stdio text REPL
# dist/ultr4rick-v<ver>-ultr4rick-dsp.uf2  on-board DSP + binary frames

Flashing:

1. Get the board into BOOTSEL. Either send reboot-dfu over the serial port, or hold BOOTSEL while plugging it in.
2. Copy the UF2 onto the RP2350 drive that appears.

Drive it from Python:

python3 -m venv .venv && .venv/bin/pip install -r requirements.txt
cd python && ../.venv/bin/python example_dsp.py      # status, DSP self-test, captures
../.venv/bin/jupyter lab                            # example_dsp.ipynb, example_acquisition.ipynb, ...

from ultr4rick.device import Ultr4rick
from ultr4rick import dsp
probe = Ultr4rick()                  # finds the board by USB ID
print(probe.status()["raw"])
print(dsp.check_selftest(probe.selftest()))
frame = probe.read_fft()             # 4096-sample Hilbert envelope

Safety: the pulser generates high voltage. The firmware boots with it disarmed. Only arm it (pulser arm / Ultr4rick.arm_pulser()) with a transducer connected, and disarm it afterwards.

License

• Hardware (hardware/): TAPR Open Hardware License v1.0
• Firmware (firmware/) and Python (python/): GPL-3.0-or-later
• Documentation (docs/ and the Markdown files): CC BY-SA 4.0

See LICENSE.md for the details and the third-party code.