UARTE Callback not called (Using NRFX EasyDMA)

[LucasD]

Hi, I am a beginner, during my internship I need to evaluate the nRF9169 DK for cellular applications.

I successfully implemented the communication over serial by using the library "drivers/uart.h". In order to get benefits of EasyDMA features, I decided to focus on the "nrfx_uarte.h" library.

I managed to create an example in blocking mode that works on UARTE2 using the functions nrfx_uarte_init(&inst, &cfg, NULL), nrfx_uarte_tx and nrfx_uarte_rx. But for some reason, when I define a callback as the third parameter of the initialisation function (using async feature) and when I want to TX few bytes: The bytes are well transmitted but the callback is never called (I used the debug to check this). The entire system is like frozen, I don't get any error/reset. The same behaviour happens during RX.

I'm not sure of the methods to debug this, I don't know if the cause can be the configuration of the project, if uarte interrupts are disabled or something else.

I'm working with : nRF Connect SDK V1.2.0 on the Segger environnement.

Please find here the zip of my project : https://drive.google.com/file/d/1qOYnxOO4wu0h6lejDumBVljWkgC8MIKH

Thank you very much for your help.

Lucas

[Hung Bui]

Hi Lucas, 

I had a look at your code. I don't see you use called variable in any function other than my_uart_callback() so it's most likely it will be optimized out by the compiler and you won't be able to see the my_uart_callback() being called. Instead you can try to toggle a GPIO pin for example. Or you can use RTT log to print out some logging when it get into the handler. 

[LucasD]

Hi Hung,

I followed your advices and I now toggle the led 1 when the callback is called. But still no results (the debugger never reach the breakpoint I set in the callback). I have the feeling that the cause is the configuration of the project ("prj.conf"), is there any guide that explains how to setup the configuration to use easyDMA on UART ?

In the same time I worked on the timers (nrfx_timers.h) and I created an example that periodically call a function. I noticed that we need to call the function IRQ_CONNECT in order to make "enable" the interrupt. I don't use this function in the uarte example,  could it be the problem ?

I attached to this message the updated uarte and timers examples I made :

https://drive.google.com/file/d/1qOYnxOO4wu0h6lejDumBVljWkgC8MIKH/view?usp=sharing

https://drive.google.com/file/d/1cEPeXJPlD7RkpkETcM0fyT-xciviYAUB/view?usp=sharing

Thanks

Lucas

[Hung Bui]

Hi Lucas, 
I did a quick check here and can see the same issue as you. I will check with the team and get back to you on Monday. 

[Hung Bui]

Hi again Lucas, 

If you have a look here: https://docs.zephyrproject.org/1.9.0/kernel/other/interrupts.html

You can find that you would need to use IRQ_DIRECT_CONNECT() to match the interrupt to the interrupt handler. 

But as you mentioned you can use UART2 I assume that you have modified the spm.conf to enable it in the non-secure domain ? 

I was testing with UART1 and here what I added to make the interrupt works: 

in prj.conf: 

CONFIG_NRFX_UARTE1=y
CONFIG_UART_1_NRF_UARTE=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_UART_1_INTERRUPT_DRIVEN=y
CONFIG_UART_1_NRF_FLOW_CONTROL=n

Note: both CONFIG_UART_INTERRUPT_DRIVEN and CONFIG_UART_1_INTERRUPT_DRIVEN are used. 

And in main.c I called this: 

IRQ_DIRECT_CONNECT(UARTE1_SPIM1_SPIS1_TWIM1_TWIS1_IRQn, 0, nrfx_uarte_1_irq_handler,0);
irq_enable(UARTE1_SPIM1_SPIS1_TWIM1_TWIS1_IRQn);

The nrfx library is bypassing the Zephyr RTOS, so it's why you need to use IRQ_DIRECT_CONNECT() 

[LucasD]

Hi Hung,

Thanks to your comments, I made the changes and the callback (UARTE2) is now working, (I hadn't understand that the nrfx library is bypassing the Zephyr RTOS). Thank you for your help ! 

Lucas