How to output a single pulse?

[BobA]

Hi,

I have a Digital Discovery. I'd like it to output a single pulse -  start high, go low for a given amount of time (e.g. 200ns), and go high again - in response to some sort of command I give it, like a virtual button push.

Is there a way to do this?

Thank you.

 

[Jeffrey]

Using the WaveForms SDK and a supported IDE such as Python or C, You can toggle a digital bit.

The Digital Discovery includes 16 channels (or bits) of digital IO.

See https://digilent.com/reference/test-and-measurement/digital-discovery/reference-manual, section 9.2 and foot note 6.

Included in the WaveForms SDK, see python examples DigitalIO.py and DigitalOut_Pulse.py, or see C example digitalio.cpp.

Note that as these are static IO, they are software controlled.  Depending on the length of the pulse, a repeatable pulse duration may not be achievable.

Though not the Digital Discovery, I have done some testing using the digital IO of the Analog Discovery 2.  The pulses range anywhere from approximately 4 kHz to 20 kHz.  This is due to latencies caused by the Windows OS. 

You will want to verify performance on your own system.

 

 

[attila]

Hi @BobA

Use the manual from the WF SDK folder and see the examples like /samples/py/DigitalOut_Pins.py
If it suits your project, the digital-out could be triggered with the trigger-io

 

dwf.FDwfDigitalOutEnableSet(hdwf, c_int(0), c_int(1)) # 0 is DIO-0 or DIO-24 for Digital Discovery
dwf.FDwfDigitalOutDividerSet(hdwf, c_int(0), c_int(1)) # use the 100MHz/10ns system frequency
dwf.FDwfDigitalOutCounterSet(hdwf, c_int(0), c_int(10), c_int(10)) # 10x10ns low 10x10ns high, 200ns

dwf.FDwfDigitalOutRunSet(hdwf, c_double(600e-9)) # run for 600ns, 3x200ns

dwf.FDwfDigitalOutTriggerSourceSet(hdwf, trigsrcExternal1)
dwf.FDwfDigitalOutRepeatTriggerSet(hdwf, c_int(1))
dwf.FDwfDigitalOutRepeatSet(hdwf, c_int(0)) # inf

dwf.FDwfDigitalOutConfigure(hdwf, c_int(1))