This is a KiCAD (v7) project design for a breakout board for the PrawnDO, a companion digital output device for the PrawnBlaster pseudo-clock generation device used in the labscript-suite. The PrawnDO is a custom firmware for the Rasperry Pi Pico microcontroller board.
This board is highly inspired by the [PrawnBlaster_Breakout][4] board.
This breakout board employs a surface mount footprint to attach the Pico as well as SMD IC and passive components, provides SMA connectorized inputs and outputs, buffering ICs at the inputs and outputs, and is designed such that all power is drawn from the Pico's power supply.
SMD passive components are no smaller than 0805 to facilitate hand soldering.
The designs in the KiCAD\gerbers subdirectory were made to be printed using a Bantham Tools CNC/PCB router.
They include only the front-side copper and edge-cuts layers with a hole drill file.
For best results, use a single-sided FR1 board with a 1/100, 1/64, and 1/32 End-Mills.
To get outputs for a fabricator, regenerate the gerber files using the fabricators desired export settings.
The PrawnDO's clock input is buffered using a 74LVC1G34 unity-gain buffer, which provides compatibility with 5VTTL clock inputs. The trigger input is buffered using a 74LVC1G17 buffer Schmitt-trigger, which provides compatibility with 5VTTL logic and handles slow rising edge trigger signals. The PrawnBlaster's sixteen outputs are buffered using four 74LVT245D octal transceivers, configured to drive in only the output direction. Each output channel of the PrawnDO uses two buffer channels in parallel to source higher currents and match the desired 50 Ohm output impedance.
It is recommended to use USB data/power isolation to power the Pico to ensure the PrawnDO grounds are not tied to the controlling computer grounds while prividing sufficient current for all devices. We use the NMUSBEVALEXC dual USB port eval board from Murata as it can provide sufficient currents.