libuarte packet fragmentation

RE: libuarte packet fragmentation

AshLabs — Wed, 03 Nov 2021 09:31:43 GMT

Hey Krzysztof. My buffer size is currently 0x420. In a pool of 3 buffers. I have a segmentation issue each 2 / 4 seconds. I implemented a system where i store the pointer of the buffer, and only free it after the second segment of the buffer segmentation is produced. This seems to work, so the issue can be closed. Thanks a lot.

RE: libuarte packet fragmentation

Krzysztof Chruscinski — Wed, 03 Nov 2021 09:29:28 GMT

Yeah, if there is an option to loose packets then you need to handle packets that spans across multiple buffers. You can increase pool of buffers then you have more time to release them.

RE: libuarte packet fragmentation

AshLabs — Tue, 02 Nov 2021 08:16:26 GMT

Thanks for the reply Krzysztof.
With the approach of disabling and re-enabling the uart i am scared that i will loose packets, which will not help me further. I tried processing multiple packets over triggered events (the callback function), but then i get into a freeing issue and fatal errors. I will investigate, thanks for the tips !

RE: libuarte packet fragmentation

Krzysztof Chruscinski — Tue, 02 Nov 2021 07:28:56 GMT

The only option to have packet in continuous memory is to disable UART and set it up again. Alternatively, you need to process packet that spans across multiple buffers.

RE: libuarte packet fragmentation

AshLabs — Fri, 29 Oct 2021 11:34:27 GMT

Yes. The problem is that i need to free this buffer or the system crashes. I don't wat to do memcpy(...) in interrupt routines, as it's time critical. So this is where the issues lie. These buffers are not circular buffers, so there is no way in consistently getting them in full array format as they are presented on the bus ?

RE: libuarte packet fragmentation

Krzysztof Chruscinski — Fri, 29 Oct 2021 11:26:35 GMT

yes, that's how it work, you will get events on timeout and on buffer boundary. You need to use some packet length decoding to process packets.