# Expansion Header in Jetson Nano expansion header

**URL:** <https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647>\
**Category:** Jetson Nano\
**Tags:** gpio\
**Created:** [August 22, 2022, 5:23am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647 "2022-08-22T05:23:22Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![bhagavath](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@bhagavath](https://forums.developer.nvidia.com/u/bhagavath)\
**Post date:** [August 22, 2022, 5:23am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647/1 "2022-08-22T05:23:22Z")

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Hi,  
What is the maximum data rate on the GPIOs connected to expansion header J41 of Jetson Nano Development kit.  
Best regards

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**Author:** ![JerryChang](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/jerrychang/32/14043_2.png) [@JerryChang](https://forums.developer.nvidia.com/u/JerryChang)\
**Post date:** [August 22, 2022, 6:03am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647/3 "2022-08-22T06:03:14Z")

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hello bhagavath,

may I know what’s the actual use-case?

you may see-also [Topic 190966](https://forums.developer.nvidia.com/t/jetson-nano-2gb-dev-kit-gpio-toggle-speed-from-python/190966/) for increasing toggle speed.  
it should use `mmap` to have faster speed, please refer to this example, [https://raw.githubusercontent.com/jwatte/jetson-gpio-example/master/gpiomem.cpp](https://raw.githubusercontent.com/jwatte/jetson-gpio-example/master/gpiomem.cpp)  
thanks

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<div class="post-metadata">

**Author:** ![bhagavath](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@bhagavath](https://forums.developer.nvidia.com/u/bhagavath)\
**Post date:** [August 22, 2022, 8:08am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647/4 "2022-08-22T08:08:08Z")

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Thanks for your response.  
I need to connect a TDC (Time to Digital converter) device to this Processor. I am planning a small add ON card which can be plugged on GPIO connector (J41). I want to know the maximum data rate supported on each of the GPIOs & dedicated pins on this connector. Can I use these GPIOs as parallel bus for better data throughput?  
Thanks

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<div class="post-metadata">

**Author:** ![JerryChang](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/jerrychang/32/14043_2.png) [@JerryChang](https://forums.developer.nvidia.com/u/JerryChang)\
**Post date:** [August 22, 2022, 8:40am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647/5 "2022-08-22T08:40:15Z")

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hello bhagavath,

you need to program the GPIO via kernel level to have better performance, it’ll depends-on your implementation logic.

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<div class="post-metadata">

**Author:** ![bhagavath](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@bhagavath](https://forums.developer.nvidia.com/u/bhagavath)\
**Post date:** [August 22, 2022, 8:54am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647/6 "2022-08-22T08:54:33Z")

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OK. Can I know what is the maximum possible data rate?

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<div class="post-metadata">

**Author:** ![JerryChang](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/jerrychang/32/14043_2.png) [@JerryChang](https://forums.developer.nvidia.com/u/JerryChang)\
**Post date:** [August 22, 2022, 9:21am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647/7 "2022-08-22T09:21:55Z")

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hello bhagavath,

please refer to [Topic 68606, comment #17](https://forums.developer.nvidia.com/t/gpio-bit-bang-speed-increase/68606/17) for the code snippets and test results.  
it’s tested on TX1 (same chip as Nano), it takes 13-sec to toggle pin for 100000-cycles. hence, the frequency of the toggle is 7692.

you may also do the same test on Nano series, the test results will correlate with CPU frequency.  
thanks

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**Author:** ![system](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/system/32/68080_2.png) [@system](https://forums.developer.nvidia.com/u/system)\
**Post date:** [September 14, 2022, 2:33am UTC](https://forums.developer.nvidia.com/t/expansion-header-in-jetson-nano-expansion-header/225647/9 "2022-09-14T02:33:09Z")

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Closed on September 14, 2022, 2:33am UTC

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