An octal TTL input-or-output board with programmable square wave output

Features

• 8x TTL output or input, configurable.
• Programmable square wave generation.
• Harp-protocol compliant (serial num: 0x057B).
• Bonus: "passthrough buffer mode." External 3.3V and 5V CMOS devices can use this device as an octal buffer with external pins.

Extra Features

• 6-20VDC input (2.1 x 5.5mm barrel jack, positive center)
• isolated USB to prevent forming ground loops with the PC.

Wiring Diagram

TODO

Theory of Operation

TODO: awesome diagram {here}

Harp Register Map

TODO