# Synchronizing clocks with C++

**URL:** <https://discourse.myriadrf.org/t/synchronizing-clocks-with-c/7332>\
**Category:** LimeSDR\
**Created:** [10 September 2021 19:55 UTC](https://discourse.myriadrf.org/t/synchronizing-clocks-with-c/7332 "2021-09-10T19:55:12Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![eldaromer](https://avatars.discourse-cdn.com/v4/letter/e/839c29/32.png) [@eldaromer](https://discourse.myriadrf.org/u/eldaromer)\
**Post date:** [10 September 2021 19:55 UTC](https://discourse.myriadrf.org/t/synchronizing-clocks-with-c/7332/1 "2021-09-10T19:55:12Z")

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Continuing the discussion from [LimeSDR ext ref clock freq and type?](https://discourse.myriadrf.org/t/limesdr-ext-ref-clock-freq-and-type/647/4):

I’d like to synchronize the clocks on my two LimeSDRs as described in this post. I’m connecting the CLK OUT from one to the CLK IN on another. However, it doesn’t look like I am able to change the setting in the Si5351C module as it doesn’t use an LMS7002m register.

Is there any way I can set this option through the C++ api?

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [14 September 2021 10:40 UTC](https://discourse.myriadrf.org/t/synchronizing-clocks-with-c/7332/2 "2021-09-14T10:40:24Z")

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Which model LimeSDR boards?

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**Author:** ![eldaromer](https://avatars.discourse-cdn.com/v4/letter/e/839c29/32.png) [@eldaromer](https://discourse.myriadrf.org/u/eldaromer)\
**Post date:** [16 September 2021 19:35 UTC](https://discourse.myriadrf.org/t/synchronizing-clocks-with-c/7332/3 "2021-09-16T19:35:34Z")

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The LimeSDR USB-A boards

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [18 September 2021 09:58 UTC](https://discourse.myriadrf.org/t/synchronizing-clocks-with-c/7332/4 "2021-09-18T09:58:12Z")

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Does this do what you need?

> <https://github.com/myriadrf/LimeSuite/blob/master/src/lime/LimeSuite.h#L923>

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**Author:** ![eldaromer](https://avatars.discourse-cdn.com/v4/letter/e/839c29/32.png) [@eldaromer](https://discourse.myriadrf.org/u/eldaromer)\
**Post date:** [23 September 2021 19:14 UTC](https://discourse.myriadrf.org/t/synchronizing-clocks-with-c/7332/5 "2021-09-23T19:14:39Z")

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It seems like it, which of these clocks is being output from the CLK OUT port? Is it CGEN?