UART API not catching RX data

RE: UART API not catching RX data

Hakon — Tue, 01 Jul 2025 10:24:10 GMT

Good stuff!

RE: UART API not catching RX data

jmerri95 — Mon, 30 Jun 2025 20:02:25 GMT

Thank you Hakon,

I got this figured out. I had the wrong understanding of why the RX pin was being held high.

Thank you,

Jack

RE: UART API not catching RX data

Hakon — Mon, 30 Jun 2025 10:13:13 GMT

[quote user="jmerri95"]If there is a way to override the RX line to keep it low all the time, I can test it in the application. [/quote]

You are asking if there is a way to keep the RX line low all the time? Can't you just set it to GND then?

RE: UART API not catching RX data

jmerri95 — Wed, 25 Jun 2025 03:16:51 GMT

Hello,

I wanted to see if you had any idea on this issue. If there is a way to override the RX line to keep it low all the time, I can test it in the application.

Thank you,
Jack

RE: UART API not catching RX data

jmerri95 — Tue, 17 Jun 2025 16:12:03 GMT

Hello,

I wanted to update this ticket... data is now coming back over the RX line but there is still the issue with RX line being held high for too long. Do you have any suggestion on how to change that?

In the image below, I trigged the interrupt twice. The first time data does not come back. The second time it does. As you can see the RX line is held high for a set duration. I am trying to change that.

Top line: TX

Mid line: Interrupt pin

Bottom line: RX

As for data coming back, The DT config I left out is below. Once I added this back in, the ASYNC API received data (on the second interrupt event)

chosen {

zephyr,osdp-uart = &uart2;

};

Thank you,

Jack

RE: UART API not catching RX data

jmerri95 — Thu, 12 Jun 2025 15:53:50 GMT

I took out the the fields you mentioned and am still seeing the same pattern. This image below is zoomed in on the left side of the total event.

RE: UART API not catching RX data

Hakon — Thu, 12 Jun 2025 10:40:47 GMT

[quote user="jmerri95"]I am assuming I am either using the wrong driver or have configured things wrong in the device tree. [/quote]

It looks fine, but you can try to remove

parity = "none";
stop-bits = "1";
data-bits = <8>;

From the uart2 node.

RE: UART API not catching RX data

jmerri95 — Wed, 11 Jun 2025 15:00:06 GMT

The line at the top is the TX data, the line in the middle is the interrupt pin (which is the trigger for this sequence), the bottom line is the RX data.

The goal is very basic - I have data i need to send to a peripheral device. The interrupt pin starts the communication, TX data is sent from the dev kit, then RX data should be received from the peripheral device.. Sequence complete

In the image below, I am trying to measure if data is coming back on the RX line, which it is (right side of the image). I do not get data back on the first interrupt trigger, only the second. The RX pin is being held high for too long and i don't know how to change that. The gap between the two points on the middle line is about 0.5 seconds.

The RX line has this pattern for Polling, ASYNC, and Interrupt. I am assuming I am either using the wrong driver or have configured things wrong in the device tree.

Thank you,

Jack

RE: UART API not catching RX data

Hakon — Wed, 11 Jun 2025 13:53:24 GMT

Did you change the order of the pins shown in the logic trace image? I don't understand what you are measuring. Why is there activity on TX at the same time as RX pin? Are you sending and receiving data at the same time?

RE: UART API not catching RX data

jmerri95 — Sat, 07 Jun 2025 18:14:05 GMT

Hi Hakon,

I got some more data here..

It looks as if I press the keypad twice in succession I can see the data come through on the logic analyzer (see the image below).

It looks like the RX line is being held high for too long, there for not registering the data. Is there any way to change this? Or remove it at all?

As for the OSDP portion, i spoke with the author of the OSDP subsys - He mentioned the file was out of date (older version of OSDP communication).

Thanks Hakon,

Jack

RE: UART API not catching RX data

Hakon — Thu, 05 Jun 2025 12:14:25 GMT

Have you tried the SDK sample? https://github.com/nrfconnect/sdk-zephyr/tree/v4.0.99-ncs1/samples/subsys/mgmt/osdp/control_panel

RE: UART API not catching RX data

jmerri95 — Wed, 04 Jun 2025 13:27:43 GMT

I am not using my own driver, I am using the ASYNC API with the 2.9.1 toolchain / SDK.

RE: UART API not catching RX data

Hakon — Wed, 04 Jun 2025 12:10:46 GMT

Why is the RX and TX pin active at the same time. This does not look normal. Did you implement your own driver?

RE: UART API not catching RX data

jmerri95 — Tue, 03 Jun 2025 14:44:55 GMT

Hi Hakon,

I have run the logic analyzer (attached the photo below).

Line 0 is TX / Line 1 is RX / Line 2 is the initiation pin.

If I change the timeout setting in the RX enable call, it still does not extend the window for RX data.. the logic pins look the same. My suspicion is that the external device does not have time to receive the data and send a response.

Do you have any suggestions on extending the RX timeout, given the uart_rx_enable call is not extending it.

Thanks

Jack

RE: UART API not catching RX data

Hakon — Mon, 02 Jun 2025 14:35:48 GMT

Hello,

do you have access to a logic analyzer? Then you can probe the RX pin to check what is going and why the RX interrupt is not triggered.