Setting CONFIG_SERIAL=n causes hardfaults

[Dave_couling]

I'm trying to optimize an Azure project based on the Asset Tracker example.  I was recommended setting CONFIG_SERIAL=n in both the Application FW and SPM.  However when I add it to the Application FW I get a hardfault fault ~1sec after modem_configure().   I haven't been able to debug why

[Carl Richard]

Hi, Dave!

The AT_HOST_LIBRARY uses the serial interface for the callbacks to the "lte_handler" defined in the sample. When CONFIG_SERIAL is set to "n" the application will crash when the AT_HOST tries to write the connection callback to UART. 

I suggest doing synchronous connection instead using "lte_lc_init_and_connect" in the "modem_configure" function. This is a blocking call that will wait for the connection to be established before proceding. 

Best regards,
Carl Richard

[Carl Richard]

Hi, again! 

Check out Stian's answer in this thread. He describes how the individual UARTs can be turned off to save power using the Zephyr power management subsystem, though I'm a bit unsure how the AT_HOST_LIBRARY will behave when doing this. 

Best regards,
Carl Richard