# ZCU111 How to switch LMK04208 to use external reference input?

**URL:** <https://discuss.pynq.io/t/zcu111-how-to-switch-lmk04208-to-use-external-reference-input/555>\
**Category:** Support\
**Created:** [October 13, 2019, 4:31pm UTC](https://discuss.pynq.io/t/zcu111-how-to-switch-lmk04208-to-use-external-reference-input/555 "2019-10-13T16:31:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![jmcoreymv](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@jmcoreymv](https://discuss.pynq.io/u/jmcoreymv)\
**Post date:** [October 13, 2019, 4:31pm UTC](https://discuss.pynq.io/t/zcu111-how-to-switch-lmk04208-to-use-external-reference-input/555/1 "2019-10-13T16:31:15Z")

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Hi,

I’m using a ZCU111 board with Pynq 2.4. Trying to figure out what is the easiest way to configure the LMK04208 to use the external reference input (basically set it to use CLKIN1 instead of CLKIN0). Hopefully without having to write any embedded C code…

Thanks!