https://test-devzone.nordicsemi.com/f/nordic-q-a/82599/max-measurable-gpio-input-frequencyHi all, I have to measure the frequency of a PWM signal routed to one of the nRF52840 GPIO pins. The signal frequency is ~3MHz. The measurement is done with the help of two timers, the code is taken from this thread : As long as the PWM frequencyen-USTelligent Community 13 Non-ProductionMon, 13 Dec 2021 14:23:52 GMThttps://test-devzone.nordicsemi.com/thread/343219?ContentTypeID=1Mon, 13 Dec 2021 14:23:52 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f1e45ece-f796-408e-b59d-8c2c1e69eb1cuser26071<p>Hello hypn0,</p> <p>Sorry for the late reply. Without having checked or done the math, I believe this frequency is about the maximum frequency possible to measure using PPI.&nbsp;</p> <p>The PPI itself is running at 16MHz. There i up to 1 tick delay on the PPI, so that gives you a 8MHz. The you have some delay in the GPIO itself. The pad capacitance is 5pF. Depending on the input signal you are measuring it will take a certain amount of time from you set the output high until the input on the nRF is actually pulled high. If this takes a few µs, then that would explain the delay you are seeing.</p> <p></p> <p>If you try to use a logic analyzer to measure your input signal, and then use the PPI to toggle a pin on every GPIO event (so that you basically duplicate the input signal), what sort of delay are you seeing between the (PWM) input and the (GPIO) output using the PWM generator that you are using?</p> <p></p> <p>Best regards,</p> <p>Edvin</p><div style="clear:both;"></div>