Unable to disable UART at runtime NCS v2.2.0

RE: Unable to disable UART at runtime NCS v2.2.0

allenyang — Fri, 31 May 2024 06:15:46 GMT

Hi,

I want to let the current of nrf5340(now is 580ua) be much lower in hello world sample,

I tried to disable UART using the code in the sample but there is a build error.

it says "undefined reference to `__device_dts_ord_142'"

How can I solve this?

prj.conf

CONFIG_PM=y
CONFIG_PM_DEVICE=y
CONFIG_PM_DEVICE_RUNTIME=y

#config RTT
CONFIG_LOG=n
CONFIG_LOG_PRINTK=n
# CONFIG_LOG_MODE_DEFERRED=y
CONFIG_CONSOLE=n
CONFIG_SERIAL=n
CONFIG_UART_CONSOLE=n
CONFIG_USE_SEGGER_RTT=n
CONFIG_RTT_CONSOLE=n
CONFIG_LOG_BACKEND_RTT=n
CONFIG_LOG_BACKEND_UART=n

# CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096
# CONFIG_LOG_BUFFER_SIZE=4096

# Disable internal DCDC
CONFIG_BOARD_ENABLE_DCDC_APP=n
CONFIG_BOARD_ENABLE_DCDC_NET=n
CONFIG_BOARD_ENABLE_DCDC_HV=n

# Use internal capacitor for 32M xtal and set capacitor value to 8.5pF 
# (ranging from 7.0 pF to 20.0 pF in 0.5 pF steps
# can be enabled on pins XC1 and XC2. This option specifies doubled
# capacitance value for the two capacitors. Set it to 14 to get 7.0 pF
# for each capacitor, 15 to get 7.5 pF, and so on.
# )
CONFIG_SOC_HFXO_CAP_INTERNAL=y
CONFIG_SOC_HFXO_CAP_INT_VALUE_X2=17
 
#  Use internal capacitor for 32k xtal and set capacitor value to 7pF 
# (only 4 options of internal capacitor value settings for 32k xtal
#   -INT_6PF
#   -INT_7PF
#   -INT_9PF
#   - USE external capacitor)
CONFIG_SOC_ENABLE_LFXO=y
CONFIG_SOC_LFXO_CAP_INT_7PF=y

Regards,

Allen

RE: Unable to disable UART at runtime NCS v2.2.0

OliverB — Thu, 19 Jan 2023 12:42:32 GMT

Got it! Your hint regarding the modem shell sample led me to the right direction. It was not a wrong device, it was just one device too few. I have to disable uart1 too. I just overlooked that uart1 is enabled in the boards device tree and thus was enabled by CONFIG_SERIAL=y too. I added

&uart1 {
	compatible = "nordic,nrf-uart";
	status = "disabled";
};

in my board overlay file. This leads to about 3,5 µA which is perfect.

Thanks and regards,
Oliver

RE: Unable to disable UART at runtime NCS v2.2.0

Sigurd Hellesvik — Thu, 19 Jan 2023 11:37:45 GMT

Hi,

For an example on how to disable UART, see the modem shell sample.

How much current draw are you measuring after calling pm_device_action_run?

Could it be that you suspend the wrong device?

Try to suspend "uart0" as in the modem shell sample, and see if you can see any difference?

Regards,
Sigurd Hellesvik

RE: Unable to disable UART at runtime NCS v2.2.0

OliverB — Thu, 19 Jan 2023 09:51:06 GMT

Fyi: I edited my code example. In line 21 it must be PM_DEVICE_ACTION_SUSPEND instead of PM_DEVICE_ACTION_TURN_OFF.