Using UART2 in Serial LTE Modem Application NCS v1.5.0

[austinaoe]

I'm having an issue getting the SLM example to compile with UART2.

Steps to reproduce:

1. Configure project with UART2
2. See error pop-up
3. Compile anyways
4. See Undefined reference to vector start

[Albrecht Markus Schellenberger]

Hello Andy,

If you have a look at the prj.conf of the Serial LTE Modem Application, you can see that there is another argument which must be set when switching to UART2:

# Use UART_2 (when working with external MCU)
CONFIG_SLM_CONNECT_UART_2=y
CONFIG_UART_2_NRF_HW_ASYNC_TIMER=2

So basically, what you should do is:

• Update to UART2

• Look for UART_2_NRF_HW_ASYNC_TIMER, update it to value 2 and press the ‘Configure’ button.

Unfortunately, there are some instabilities with Kconfig in NCS v1.5.0, so what I recommend you do instead is:

• Open the prj.conf file of the Serial LTE Modem Application in a text editor of your choice, toggle the comment for the two parameters below and save the changes.

# Use UART_2 (when working with external MCU)
CONFIG_SLM_CONNECT_UART_2=y
CONFIG_UART_2_NRF_HW_ASYNC_TIMER=2

• Run a CMake update in SES.

You should now be able to build the application. Let me know if you have any more questions.

Cheers!

Markus

[austinaoe]

Hi Markus, looks like it works!

I'm curious if the RTS and CTS are required?  I'm not using them and the application seems to be working fine.