Switching from UART_INTERRUPT_DRIVEN to UART_ASYNC_API in USB CDC ACM Sample Leads to Fatal Error

[Omar]

Hello,

I am working with the USB CDC ACM Sample Application from NCS V2.1.0 on nRF52840DK and have encountered an issue when attempting to replace the UART_INTERRUPT_DRIVEN API with the UART_ASYNC_API.

Steps Taken:

1. I took the standard USB CDC ACM Sample Application from the NCS V2.1.0 samples.
2. I modified the code to switch from using UART_INTERRUPT_DRIVEN to UART_ASYNC_API.

Problem:

After making the changes and using the uart_tx() function, I encountered a fatal error. Below are the details:

Here are the screenshots showing the code differences and the specific error messages encountered:

PS: i defined uart_cb() above, and i just put a switch case and some comments, and for the tx_buf[] i initialized it with some text.

And here are the prj.conf changes

Error Message:

I would appreciate any insights or guidance on why switching to UART_ASYNC_API is causing this issue and how to resolve it. Specifically, I am looking for:

1. Correct procedure to transition from UART_INTERRUPT_DRIVEN to UART_ASYNC_API for the USB CDC ACM application.
2. Any known issues or considerations when using UART_ASYNC_API in this context.

Thank you for your assistance!

[Hieu]

Hi Omar,

Please refer to the discussion here and let me know if it helps.

 Cannot get Async UART0 to work with USB CDC 

Hieu

[Omar]

So the conclusion "CDC ACM does not support the Async API in zephyr"
However, I’m wonderingif this issue has been addressed in newer versions. As I mentioned, I'm currently using NCS V2.1.0 == Zephyr V3.1.99

Thank you

[Hieu]

I don't think anything is different in NCS v2.1.0. In that DevZone discussion, at least one of the NCS versions used was v2.4.2, stated in the opening post.

[Omar]

Okay thank you

[Hieu]

No problem. Sorry we couldn't achieve what you wanted to do. Please feel free to close this case at your convenience.