Cannot disable UART0 on nRF9160 via overlay file when ASYN UART1 is used.

Question

Hi Nordic, 
 I am using Circuitdojo nRF9160 to develop a low-power application. In my application, I want to use one of the board's UART interfaces to communicate with a sensor via ASYN UART. 
 And, I have some issues: 
 1. In case I enable and use ASYN UART1 to communicate with the sensor, and I want to disable UART0 via the overlay file to save energy. The program always appears with errors. However, when I disable the UART1 (via overlay), I can disable UART0 easily without any errors. Could you please tell me why? I cannot find the reason. 
 2. In case I cannot disable UART0 when I am using ASYN UART1, there is another way. I can use UART0 as an ASYN UART to communicate with the sensor. Is it feasible? and if yes, how I can prevent it from printing messages while I am still able to use it to communicate with the sensor normally? 
 
 Thank you for your support! 
 
 Best regards, Vu

Michal · Accepted Answer

Hello Vu, 
 Could you show me what kind of error are you getting? 
 Best regards, 
 Michal

Hieu · Answer

Hi Vu, 
 Our apology for the long silence. Michal has been on some other assignments and the case slipped past our checks for some reasons. 
 The problem is that UART0 is still used by some other features of the Zephyr RTOS. See this part of the CircuitDojo board definition : 
 chosen {
 zephyr,console = &uart0;
 zephyr,shell-uart = &uart0;
 zephyr,uart-mcumgr = &uart0;
	}; 
 
 The console, shell, and MCUmgr features still expect UART0. 
 You have two options: 
 
 Disable the features via Kconfig 
 Overlay the features' UART selection to UART1 
 
 Regards, 
 Hieu

Cannot disable UART0 on nRF9160 via overlay file when ASYN UART1 is used.

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