Headstage 64 GPO Trigger

The following excerpt from the Headstage 64 example workflow demonstrates triggering a stimulus following a press of the □ key on the breakout board. The GPO trigger toggles a pin on the headstage to trigger stimulus which occurs more instantaneously than writing to a register on the headstage's FPGA which is how the Headstage64ElectricalStimulatorTrigger and Headstage64OpticalStimulatorTrigger operators trigger stimuli.

Note

If both stimulators are armed when the GPO is triggered, both optical stimulus and electrical stimulus are delivered. If you want to use GPO to trigger both types of stimulus independently, you must dynamically arm and disarm the respective stimulator.

The DigitalInput operator generates a sequence of DigitalInputDataFrames. Although the digital inputs are sampled at 4 Mhz, these data frames are only emitted when the port status changes (i.e., when a pin, button, or switch is toggled) when DigitalInput's SampleRate property is left blank such as is done in the example workflow. The DigitalInput's DeviceName property is set to "BreakoutBoard/DigitalInput". This links the DigitalInput operator to the corresponding configuration operator.

Buttons is selected from the DigitalInputDataFrame and passed to a HasFlags operator, which filters the sequence based on which button is pressed using the Value property's dropdown menu. In this case, HasFlags's Value is set to "Square", so its output is "True" when an item its input sequence contains a "Square" flag. The DistinctUntilChanged operator only passes an item in its input sequence if it's different from the previous item in the input sequence. When the Headstage64GpoTrigger operator receives a "True" value in its input sequence, a stimulus waveform is triggered.