wait state after trigger in DwfDigitalIn

[Bjorn]

To increase the time-resolution when measuring delays between pulses with the Analog Discovery 2 (using the SDK)  I would like to have a wait-state after a trigger have occurred when sampling digital in-data. For example, I expect that after a high signal on IO pin 1 a high signal will occur on IO pin 2 after about one second. I can set the maximum buffer size to 4096 and a divider so that the sampling after the trigger on IO pin 1 will sample for about one second. But that means that the timing resolution of each sample is about 1/4096, or about 0,2 ms. If I could set a wait-counter for 0,99 seconds and then sample at maximum frequency from 0,99 seconds to 1.01 seconds I could increase the resolution for the second pulse detection to 0,02/4096, or about 5 us.

Is there a solution to increase the sampling resolution at a delayed offset to a trigger in digital in?

[JColvin]

Hello @Bjorn,

I have moved your question to a more appropriate section of the Forum where the engineer best suited to help you will be able to see and respond to your question.

Thanks,
JColvin

[attila]

Hi @Bjorn

You can set the trigger position to 1 second and perform acquisition on a small time span, like 80us with 100Mhz of 8000 samples. With this the trigger position + 1 second will be in the middle of the capture. With 0.99996 second (1-40us) it will be the beginning of the capture.

[Bjorn]

I cannot see how to do this for DigitialIn. AnalogIn have the posibility to set a triggerPosition which defines a horzontal trigger position in seconds. However the DigitalIn TriggerPositionSet sets a "number of samples to acquire after the trigger" and does not define a wait time in seconds. One possibility might be to instead use the analog channels and detect the pulses there, but since the pulses are digital the digitalIn is a better match. DigitalOut have a wait state. Maybe I could trigger DigitalOut, let that wait for 0.99996 seconds and then let that somehow trigger the DigitalIn capturing?

 

[attila]

Hi @Bjorn

Oh... for Digital In... sorry
With FDwfDigitalInTriggerPositionSet for single/repeated acquisition you specify the end of the acquisition relative to trigger event. With FDwfDigitalInBufferSizeSet the number of samples to acquire.
So for 100MHz acquisition and position of 100M the last sample of the capture will be 1 second after the trigger event.
To have the trigger position + 1 second in the middle of the capture set position to = (1 second) x (sample rate) + (buffer size)/2