An 8-channel TTL input-or-output device with programmable square wave output

Features

• 8x TTL input or output, configurable.
• Direct PC control of IO Pins:
  • set pins configured as output to either HIGH (5V) or LOW (0V)
  • read the state of pins configured as inputs as either HIGH (~5V) or LOW (~0V) at TTL logic levels.
• Programmable square wave generation with many configurable settings:
  • PWM Frequency range: from 0.01Hz to 2KHz
  • Duty Cycle
  • Offset
  • number of pulses (or infinite)
• Input Capture. Configure pins as inputs to detect
  • rising edges (up to 500Hz)
  • falling edges (up to 500Hz)
  • both! (up to 500hz)
• 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.

Note

This board produces digital outputs and measures digital inputs only! For producing high fidelity analog outputs, refer to the harp.device.quac device.

Extra Features

• 6-24VDC input (2.1 x 5.5mm barrel jack, positive center)
• reverse polarity protection
• soft start
• isolated USB to avoid forming ground loops with the PC.

PWM Waveform Setup

Each IO pin is capable of producing a PWM output. Here are the settings available:

• offset_us: how long (in microseconds) the output should remain LOW before switching the output HIGH in one period.
• on_duration_us: how long (in microseconds) the output should remain HIGH in one period.
• off_duration_us: how long (in microseconds) the output should remain LOW in one period.
• cycles: how many pulses to produce or zero for infinite pulses until disabled.
• invert: whether the output should be inverted (on-time refers to the output being LOW instead).

Note

Although multiple PWM channels can be set to different settings and produce outputs concurrently, all PWM outputs must be started at the same time.