nrf52 DK: UART problems

RE: nrf52 DK: UART problems

FormerMember — Fri, 31 Mar 2017 11:00:06 GMT

In APP_UART_FIFO_INIT, the function name for the event handler is passed as an argument. As you can see in the source code: APP_UART_FIFO_INIT() --> app_uart_init(), the UART event handler is assigned to m_event_handler (app_uart_fifo.c). In case of an UART event, uart_event_handler (app_uart_fifo.c) will pass the event to the assigned m_event_handler.

In app_uart_fifo.c, uart_event_handler() is set to be the event handler function in app_uart_init() --> nrf_drv_uart_init().

RE: nrf52 DK: UART problems

H4NNE5 — Thu, 30 Mar 2017 08:43:05 GMT

OK, thank you for making that clear. So that's the difference I already pointed out in my initial question but lacking knowledge of the internal UART procedures, I couldn't conclude which impact "error" or "event handle" would have. I still don't understand how during the "APP_UART_FIFO_INIT", "error" or "uart handle" are passed without the required "p_event" pointer. Can you please also explain that to me?

RE: nrf52 DK: UART problems

FormerMember — Wed, 29 Mar 2017 12:28:51 GMT

After testing your example, and comparing it with the "bare" uart example in the SDK, I realized why app_uart_get() always returns NRF_ERROR_NOT_FOUND (0x05): The mechanism in the "bare" uart example and ble_app_uart is different. The bare UART example uses polling/pulling to check if characters have been transmitted over UART, while ble_app_uart is event driven. The difference between the two examples lies in uart_error_handle (uart) and uart_event_handle (ble_app_uart).

In the bare uart example, uart_error_handle does only check for communication errors, and does not handle incoming data.

In ble_app_uart, uart_event_handle will handle the event for incoming data (APP_UART_DATA_READY). Since UART is running on higher priority than main(), uart_event_handle --> APP_UART_DATA_READY --> app_uart_get() will always the data before app_uart_get() in main. app_uart_get() in main will return NRF_ERROR_NOT_FOUND because all incoming characters have already been read.

RE: nrf52 DK: UART problems

FormerMember — Mon, 27 Mar 2017 08:56:27 GMT

Did you upload your project file?

RE: nrf52 DK: UART problems

H4NNE5 — Thu, 23 Mar 2017 14:05:01 GMT

First: I can't upload my project files to this answer (see the Top in Capital letters). Why?

Second: In your python script RTSCTS Flow Control was set to 1 while in the main.c the Flow Control was disabled. That's why I had strange behavior. And Flow Control HAS to be enabled. Program gets stuck if it's disabled. But the errorcode is still 0x05. So please check out my project file, if I can upload it.

RE: nrf52 DK: UART problems

FormerMember — Thu, 23 Mar 2017 10:23:56 GMT

The uart_event_handle is provided upon UART initialization, and since there will be a UART interrupt upon a reception over UART, it is normal that the uart_event_handle will be called. In the small example I uploaded, the softdevice is not enabled, no BLE link, etc., so the firmware should go to the error handler after calling ble_nus_string_send() (I believe)).

The priority of uart_event_handle is APP_IRQ_PRIORITY_LOWEST, which is higher than the main loop. Therefore, if characters are sent continuously over UART, there will always be a UART interrupt, and it will not be possible to return to the main thread.

RE: nrf52 DK: UART problems

H4NNE5 — Wed, 22 Mar 2017 12:04:54 GMT

The DK received the bytes from the script using the uart example but not in the ble-example.

Yes, the ble_app_uart example worked fine. Only after I got that running I started with this UART experiment.

Update: The Characters appear inside the "m_rx_fifo" struct so the RX is setup correctly and also after each received character the "err_code" is 0x00, but after leaving "app_uart_get" the program doesn't jump back into your routine but inside the routine "uart_event_handle" which is part of the "main.c" which is weird.

Btw. Thank you for your intensive help on this problem! That's highly appreciated.

RE: nrf52 DK: UART problems

FormerMember — Wed, 22 Mar 2017 11:39:59 GMT

Also, does ble_app_uart in the SDK work for you? Are you able to transfer data from the PC to the peripheral device?

RE: nrf52 DK: UART problems

FormerMember — Wed, 22 Mar 2017 11:38:49 GMT

Could you try this python script for pushing data from the PC over UART for a given COM port, and check if that change anything?

RE: nrf52 DK: UART problems

H4NNE5 — Wed, 22 Mar 2017 11:34:54 GMT

Same here. If I use the UART example, the echo function works also for single characters.

Can you find out if it's important if the UART flow control is disabled or enabled and the difference between uart_event_handle and uart_error_handle in "APP_UART_FIFO_INIT"? Because as mentioned above, these are the differences inbetween both examples.

RE: nrf52 DK: UART problems

FormerMember — Wed, 22 Mar 2017 11:32:19 GMT

How do you transfer data from the terminal to the DK? Do you type characters in the terminal? That is what I do. Sometimes, I have the impression that the terminal will not transfer one character only, but rather wait for multiple characters to transfer.

RE: nrf52 DK: UART problems

H4NNE5 — Wed, 22 Mar 2017 10:06:37 GMT

Alright, the missing softdevice was the cause. The memorysettings didn't have to be adapted, because I took the project file right out of the example folder. However the frequency setting was at 12MHz instead of 64 like in your image. But with debug running now I still don't get a "NRF_SUCCESS". Weird. For "got_character" and "cr" I get a "not in scope" in my Watch1. How do you upload pictures here in the comments? I wanted to share my screenshot.

Update: OK, they were "not in scope" because they get optimized away. I set the optimization level to 0. But the errorcode in "app_uart_get" is still 5.

RE: nrf52 DK: UART problems

FormerMember — Wed, 22 Mar 2017 09:44:04 GMT

RE: nrf52 DK: UART problems

FormerMember — Wed, 22 Mar 2017 09:41:05 GMT

Did you remember to flash the softdevice, S132 v. 4.0.2? And change the RAM/ROM settings for the project?

RE: nrf52 DK: UART problems

H4NNE5 — Wed, 22 Mar 2017 09:11:54 GMT

Ok, Thanks. Of course I forgot to update the sdk_config-file... Now it compiles correctly but the next problem that emerges is that in debug mode is that the debugging isn't reaching the main() routine. It get's stuck somewhere running in a dead loop.

RE: nrf52 DK: UART problems

FormerMember — Wed, 22 Mar 2017 08:08:50 GMT

I have updated my answer.

RE: nrf52 DK: UART problems

H4NNE5 — Tue, 21 Mar 2017 15:00:00 GMT

Hi Kristin, I integrated the new SDK and the example's project file and adapted the links to the header files but I still get this error: Error List

Update: Here is my project folder content: I CANT UPLOAD THE FILE FROM MY COMPUTER :(

RE: nrf52 DK: UART problems

FormerMember — Mon, 20 Mar 2017 11:33:08 GMT

I have updated my answer.

RE: nrf52 DK: UART problems

H4NNE5 — Fri, 17 Mar 2017 14:36:49 GMT

Yes that's exactly the error I get from debugging. So I guess it must have to do with a wrong configuration, but which? Because I thought I checked all UART configuration between the 2 examples...

RE: nrf52 DK: UART problems

FormerMember — Fri, 17 Mar 2017 13:49:01 GMT

Aha, I misunderstood, I thought you connected two nRF52-DKs together.

When you connect the nRF52-DK to a serial port on a PC, does app_uart_get() return NRF_SUCCESS if you send some characters from the terminal to the nRF52-DK? If app_uart_get() returns NRF_ERROR_NOT_FOUND is means that there is no data in the RX buffer.

RE: nrf52 DK: UART problems

H4NNE5 — Fri, 17 Mar 2017 13:20:43 GMT

Do you know what the UART example is doing? It's establishing a connection from the board to the PC using the virtual COM port over USB and echoing UART communication that's coming from the PC. So there's no need to check any connection. Also I wrote that the UART example itself is working fine. Maybe you didn't see that I'm using your Development Kit (PCA10040).

RE: nrf52 DK: UART problems

FormerMember — Fri, 17 Mar 2017 13:15:53 GMT

Could you double check that you have connected the boards correctly together?

TX <--> RX
RX <--> TX

Update 20.03.2017: I have tested similar code here, based on ble_app_uart (SDK 13), and in that case app_uart_get(..) will receive characters from the terminal. Could you test my code, and check if it work on your side? The project should be used with S132 v.4.0.2.

ble_app_uart_UART_only.zip

Update 22.03.2017: APP_TIMER_CONFIG_RTC_FREQUENCY should have the following definition in sdk_config.h.