Cuttlefish

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.