Question about digital capture

[phell]

I am trying to understand what happens if I tell a digital input to wait for the signal to go low. The Bluetooth bandwidth gives an update rate of 200 Hz. What happens if the Signal goes low more often than every 5 ms? Do I only get information that the signal has gone low at least once during those 5 ms? What I want to do is measuring the time between the last two times a signal goes low. I understand pulse input does this as well but I want to compare the results I get with digital input waiting for signal to go low with the information I get with pulse input. The signal I want to measure is a square wave with a frequency up to 30 Hz.

[Ytai Ben-Tsvi]

On Wed, Mar 23, 2016 at 4:07 AM, phell <phe...@gmail.com> wrote:

I am trying to understand what happens if I tell a digital input to wait for the signal to go low. The Bluetooth bandwidth gives an update rate of 200 Hz. What happens if the Signal goes low more often than every 5 ms?

You'd be saturating the link. Not good.

 

Do I only get information that the signal has gone low at least once during those 5 ms?

No. You'll get all the transitions. It is not intended for high-speed signals.

 

What I want to do is measuring the time between the last two times a signal goes low. I understand pulse input does this as well but I want to compare the results I get with digital input waiting for signal to go low with the information I get with pulse input. The signal I want to measure is a square wave with a frequency up to 30 Hz.

Indeed, PulseInput is the way to go. You can do this the way you suggest at this frequency, but your measurement will be very imprecise, especially over BT, where the jitter is high. 

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[phell]

I see. I thought there was a time stamp on Bluetooth traffic so I could calculate the difference in time that way. The jitter will force me to use PulseInput.