NRFX Uarte invalid data after framing error

RE: NRFX Uarte invalid data after framing error

Kenneth — Fri, 10 Jan 2025 15:02:34 GMT

The uart may operate in two different modes, the easydma (uarte) and the legacy interrupt based (uart). You can change between the two in the devicetree by using

compatible = "nordic,nrf-uarte";
vs.
compatible = "nordic,nrf-uart";

Do using uart work better in this case?

Kenneth

RE: NRFX Uarte invalid data after framing error

HinnaX — Fri, 10 Jan 2025 07:40:18 GMT

I've found here some information about this topic.
https://docs.nordicsemi.com/bundle/ps_nrf52840/page/uarte.html#ariaid-title5

"If there was a framing error (wrong stop bit), that specific byte will NOT be stored into Data RAM, but following incoming bytes will."

So it need a workaround to get the current byte at the framing error.

RE: NRFX Uarte invalid data after framing error

Kenneth — Thu, 09 Jan 2025 20:12:11 GMT

[quote user="HinnaX"] So the distance or the time between end of last normal data packet and start of framing error packet is 1,2 ms.[/quote]

Interesting, I guess in this case that once the UART experience the framing error it unintentionally overwrite the last received byte on the buffer. I can't see any other reason. Since this is handled in hardware it's very little that can be done with it, other than to try to workaround it by reading the buffer faster or delaying the sync bit?

Enneth

RE: NRFX Uarte invalid data after framing error

HinnaX — Wed, 08 Jan 2025 14:14:12 GMT

Hey Kenneth,
thanks for your reply. So the distance or the time between end of last normal data packet and start of framing error packet is 1,2 ms.

"Is it possible that the pointer or buffer is updated on framing error? "

What do you mean with that question? So between the RX_DONE event and the RX_EVT_ERROR there is no update from my code side.

RE: NRFX Uarte invalid data after framing error

Kenneth — Wed, 08 Jan 2025 12:27:53 GMT

Hello,

I think I would have looked that the serial interface using a logic analyzer just be sure you have full control over the start, data, and stop bit, and that that the framing error actually occurs after a correctly received byte. What is the distance between the two? Is it possible that the pointer or buffer is updated on framing error?

That said, you may want to check out the nRF54L for new designs, it have some new features for UARTE:
https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/uarte.html

Kenneth

RE: NRFX Uarte invalid data after framing error

HinnaX — Wed, 08 Jan 2025 11:00:09 GMT

So 255 is value of the byte before the framing error occurs.