# PYNQ-Z1 board I/O pins switching speed

**URL:** <https://discuss.pynq.io/t/pynq-z1-board-i-o-pins-switching-speed/5394>\
**Category:** Support\
**Created:** [March 22, 2023, 3:55pm UTC](https://discuss.pynq.io/t/pynq-z1-board-i-o-pins-switching-speed/5394 "2023-03-22T15:55:53Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![rydhslmy](https://avatars.discourse-cdn.com/v4/letter/r/bbce88/32.png) [@rydhslmy](https://discuss.pynq.io/u/rydhslmy)\
**Post date:** [March 22, 2023, 3:55pm UTC](https://discuss.pynq.io/t/pynq-z1-board-i-o-pins-switching-speed/5394/1 "2023-03-22T15:55:53Z")

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Hi, I am trying to use the PYNQ-Z1 to read the digital outputs from an external ADC. I am also trying to generate the sampling clock for the ADC from the PYNQ-Z1 board itself. Therefore I want to know what is the maximum switching speed of the I/O pins if I want to output a 3.3V clock signal from the I/O pins?

P.S. I have read the PYNQ-Z1 board reference manual but the documentation doesn’t mention anything about it. It is only mentioned that the Pmod port in this board is the high-speed type, but the documentation doesn’t tell you exactly the maximum speed.