UART example goes to debug window

[ProtonTim]

I have been developing some nrf52832 code (SDK 17.0.2) using the Segger RTT debug window for logging.  I added the code from the UART example but the printf goes to the debug window not the UART.

In my sdk_config file I have the following:

// NRF_LOG_BACKEND_SERIAL_USES_UART - If enabled data is printed over UART
//==========================================================
#ifndef NRF_LOG_BACKEND_SERIAL_USES_UART
#define NRF_LOG_BACKEND_SERIAL_USES_UART 1
#endif

// NRF_LOG_BACKEND_SERIAL_USES_RTT - If enabled data is printed using RTT
//==========================================================
#ifndef NRF_LOG_BACKEND_SERIAL_USES_RTT
#define NRF_LOG_BACKEND_SERIAL_USES_RTT 0
#endif

//==========================================================
// <e> NRF_LOG_BACKEND_RTT_ENABLED - nrf_log_backend_rtt - Log RTT backend
//==========================================================
#ifndef NRF_LOG_BACKEND_RTT_ENABLED
#define NRF_LOG_BACKEND_RTT_ENABLED 0
#endif

// <e> NRF_LOG_BACKEND_UART_ENABLED - nrf_log_backend_uart - Log UART backend
//==========================================================
#ifndef NRF_LOG_BACKEND_UART_ENABLED
#define NRF_LOG_BACKEND_UART_ENABLED 1
#endif

// <o> NRF_LOG_BACKEND_UART_TX_PIN - UART TX pin
#ifndef NRF_LOG_BACKEND_UART_TX_PIN
#define NRF_LOG_BACKEND_UART_TX_PIN 6
#endif

What else needs to be done to get the UART example to output on the UART and not on RTT?

Thanks for your help,

Tim

[Jared]

Hi,

Have you enabled the RETARGET config in the sdk_config file?: 

#ifndef RETARGET_ENABLED
#define RETARGET_ENABLED 1
#endif

You also need to add the path to retarget.c to the project.

regards

Jared 

[ProtonTim]

I switched on RETARGET_ENABLED and added retarget.c to the project.  Now it no longer directs the printf output to the debug window, but I don't see anything on the terminal.  When I run the uart example code on my hardware it prints to the terminal so I know the hardware is working and my pinout is correct.  Anything else I might be missing? Seems like it is still a config or library issue.

One more issue.  It looks like I cannot mix sending things out the UART with the example code AND sending logging messages to the RTT is that true?  I know it is not a hardware limitation but is it a code limitation of the library used in the UART example?  If so can you refer me to an example of how to use the UART independent of the logging?  I am thinking of just writing the low level drivers myself if necessary.

Thanks for your help.

Tim

[Jared]

Hi,

Could you share your entire config file?

regards

Jared 

[ProtonTim]

Yes I will share it.  I enabled  UART0_CONFIG_USE_EASY_DMA and now I get the first character of the printf string coming out the port followed by a carriage return.  Is the best way to share it to paste it into a code window?  I don't see an easy way to attach it.

[ProtonTim]

I attached it as a source code block, but it looks like it got removed.

[Jared]

Hi,

Press insert->Image/video/file in the reply box and chose upload. Select your file and you should see that it's uploaded as an attachment. 

Jared 

[ProtonTim]

5657.sdk_config.h

[ProtonTim]

Jared,  I was able to get the printf to work.  Once I got the config right I had to add a delay to let the characters come out.  I am going to switch the logging back to RTT now.  Hopefully the printf and RTT logging will work together nicely as you noted.  Thanks for the help.

Regards,

Tim

[ProtonTim]

Jared,

The printf function works, but now my program does not!!  I have some nrf_delay_ms(100) in the program and it seems to lockup on those statements.  For instance I break on the red() function and then hit the step over button the debugger goes away.  When I hit pause I can see it is stuck in app_error().  None of this happened before adding the printf functionality. Do you know what I broke?

while(!pb_pressed()) // wait for button to be pressed to start test
{
red();
nrf_delay_ms(100);
green();
nrf_delay_ms(100);
blue();
nrf_delay_ms(100);
}

[ProtonTim]

Here is the call stack.  Not exactly sure what to make of it.

[Jared]

Hi,

 My guess is that it goes into the error handler in app_uart.c or app_uart_fifo.c. 

app_uart_event.data.error_communication is set in the error handler and will contain the value in the ERRORSRC register for the UART peripheral. Use the debugger and check what value this is set to.

Also, regarding the logging module, are you using deferred or in-place logging when you log over RTT? 

regards

Jared 

[ProtonTim]

I found the issue.  When I configure the I2S port with nrf_drv_i2s_init() the ERRORSRC for the UART gets set to 0xC.  Why would the I2S effect the UART?  Do they share resources?  How can I make them play nicely together? 

Thanks,

Tim