# Nunavut does not produce the data type signature

**URL:** <https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619>\
**Category:** Nunavut\
**Created:** [March 22, 2022, 11:43am UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619 "2022-03-22T11:43:15Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![FliyOvis](https://forum.opencyphal.org/letter_avatar_proxy/v4/letter/f/d6d6ee/32.png) [@FliyOvis](https://forum.opencyphal.org/u/FliyOvis)\
**Post date:** [March 22, 2022, 11:43am UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619/1 "2022-03-22T11:43:15Z")

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command: nnvg --target-language c …  
The output c header files do not contain the data type signature which is used for frame crc calculation,  
so how to use this dsdl tool ?

Thanks

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**Author:** ![pavel.kirienko](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/pavel.kirienko/32/9_2.png) [@pavel.kirienko](https://forum.opencyphal.org/u/pavel.kirienko)\
**Post date:** [March 22, 2022, 12:40pm UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619/2 "2022-03-22T12:40:47Z")

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UAVCAN v1 does not use data type signatures.

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<div class="post-metadata">

**Author:** ![FliyOvis](https://forum.opencyphal.org/letter_avatar_proxy/v4/letter/f/d6d6ee/32.png) [@FliyOvis](https://forum.opencyphal.org/u/FliyOvis)\
**Post date:** [March 23, 2022, 2:26am UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619/3 "2022-03-23T02:26:40Z")

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The signature is used to calculate crc in the code of c++ libuavcan and libcanard,  
is there some options to make Nunavut compatible with the signature?  
or which dsdl compiler can I use if the signature is needed?

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<div class="post-metadata">

**Author:** ![FliyOvis](https://forum.opencyphal.org/letter_avatar_proxy/v4/letter/f/d6d6ee/32.png) [@FliyOvis](https://forum.opencyphal.org/u/FliyOvis)\
**Post date:** [March 23, 2022, 2:39am UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619/4 "2022-03-23T02:39:22Z")

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OK, the problem is that the uavcan library I used is based on UAVCAN v0, now I want to refine the app code not using the uavcan library but only the compiled dsdl. is Nunavut compatible with UAVCAN v0?

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**Author:** ![pavel.kirienko](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/pavel.kirienko/32/9_2.png) [@pavel.kirienko](https://forum.opencyphal.org/u/pavel.kirienko)\
**Post date:** [March 23, 2022, 10:41am UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619/5 "2022-03-23T10:41:02Z")

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Nunavut is only compatible with v1.

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<div class="post-metadata">

**Author:** ![FliyOvis](https://forum.opencyphal.org/letter_avatar_proxy/v4/letter/f/d6d6ee/32.png) [@FliyOvis](https://forum.opencyphal.org/u/FliyOvis)\
**Post date:** [April 12, 2022, 2:41am UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619/6 "2022-04-12T02:41:52Z")

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Thanks Pavel.  
I found the v1 bit order is opposite with v0 when not byte aligned, which is not compatible.  
so is there any document for the changes from v0 to v1?

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<div class="post-metadata">

**Author:** ![pavel.kirienko](https://forum.opencyphal.org/user_avatar/forum.opencyphal.org/pavel.kirienko/32/9_2.png) [@pavel.kirienko](https://forum.opencyphal.org/u/pavel.kirienko)\
**Post date:** [April 12, 2022, 12:47pm UTC](https://forum.opencyphal.org/t/nunavut-does-not-produce-the-data-type-signature/1619/7 "2022-04-12T12:47:40Z")

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Yes, it is here: [The Cyphal Guide - Applications & Usage - OpenCyphal Forum](https://opencyphal.org/guide)