LAUNCHXL-CC1352R1: UART receive interrupt

Jose Simoes

Hi,

I'm need to wait from data arriving at the UART, which I don't know when it will arrive not the length of it.

Typically there is in the UART APIs an handler that's called where data arrives at the UART or when there is data available to read.

I can't find this pattern in the SimpleLink UART2 API...

The closest I can think it to fire a task trying to read a single char with infinite timeout, but that feels a bit awkward...

Am I missing something here? Can you please let me know how this common use case should be addressed with SimpleLink UART2 API.

Thanks!

over 4 years ago

0 Marie H over 4 years ago

TI__Guru* 82601 points

Hi Jose,

What you are describing sounds like callback mode. It's descirbed in the documentation and we also have an example implementation:

- https://dev.ti.com/tirex/explore/content/simplelink_cc13x2_26x2_sdk_5_10_00_48/docs/drivers/doxygen/html/_u_a_r_t2_8h.html

- https://dev.ti.com/tirex/explore/node?node=AKfUjB-7T.zLkgD27sw41Q__pTTHBmu__LATEST

Cheers,

Marie H

0 Jose Simoes over 4 years ago in reply to Marie H

Intellectual 460 points

Hi Marie,

I've read that doc and samples. The description clearly states that "UART2 provides for event notification, allowing the application to receive TX start and completion events, and RX error events".
It's "missing" an RX data received event. The only callback usable for RX is to receive RX errors.

Looking at the SimpleLink code, what I'm asking it's there and working to fill in the RX ring buffer. Just that's not exposed in the API, making it hard or difficult to use the way I'm describing. (which I believe it's a pretty common use case for UART and commonly available in MCU UART APIs).

Looking forward for your follow up .

0 TER over 4 years ago in reply to Jose Simoes

TI__Guru**** 317180 points

Not following you. In the example Marie pointed to you have the following code:

status = UART2_read(uart, &input, 1, NULL);

As the example is setup the callback is therefore called when you have received 1 byte on the UART. Isn't it this you need? If not, please elaborate.

0 Jose Simoes over 4 years ago in reply to TER

Intellectual 460 points

Hey @TER,

Like I've described in the original question, I would like to "just" be notified that there-is-data-available-for-reading. Then, on the callback, it would be be decided to read N bytes from the ring buffer.

As it is now, the only way to read data is calling UART2_read().

What is your suggestion for an app to wait continuously for data arriving at the UART? In particular if the protocol has variable length.

0 Marie H over 4 years ago in reply to Jose Simoes

TI__Guru* 82601 points

Hi Jose,

I don't think what you're describing is possible with only the UART. How about implementing another GPIO between the devices for this "message ready" signal?

Cheers,

Marie H.

0 Jose Simoes over 4 years ago in reply to Marie H

Intellectual 460 points

Hi Marie,

I'm afraid that's not possible. This should be possible to accomplish without hardware flow control.

Like I've said, the code it's already there (in the UART2 API) it's a matter of exposing a callback when data is added to the RX ring buffer.

Please consider adding the is improvement in a future version of the SDK. As it is now, software flow control is not possible without extra code.

Cheers,

0 Jose Simoes over 4 years ago in reply to Jose Simoes

Intellectual 460 points

Hi Marie,

Was wondering if you had any update/ffedback on the above?

Thanks,

Sub-1 GHz

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LAUNCHXL-CC1352R1: UART receive interrupt