Can't connect to nRF cloud when UI Module disabled (Asset Tracker, Thingy 91)

[andrew926]

Hello,

I want to measure current consumption of nRF9160 of the Thingy 91 with the Asset Tracker application in PSM mode without GPS. For that, I added to the function modem_configure in main.c the lines

int err = 0;

#if defined(CONFIG_LTE_POWER_SAVING_MODE)
		err = lte_lc_psm_req(true);
		if (err) {
			LOG_ERR("PSM request failed, error: %d", err);
			return err;
		}

		LOG_INF("PSM mode requested");
#endif

I also changed data sending interval to 300 s and disabled LEDs, buzzer and NMOS in prj_thingy91_nrf9160ns.conf:

CONFIG_ENVIRONMENT_DATA_SEND_INTERVAL=300
CONFIG_LIGHT_SENSOR_DATA_SEND_INTERVAL=300
CONFIG_HOLD_TIME_RSRP=300

CONFIG_UI_LED_USE_PWM=n
CONFIG_UI_BUZZER=n
CONFIG_UI_NMOS=n

I tested it in LTE Link Monitor and PSM was successfully activated with my desired TAU (00100001 = 1 hour). I did not enable eDRX.

After that I disabled logging by editing the prj_thingy91_nrf9160ns.conf:

CONFIG_LOG=n
CONFIG_SERIAL=n
CONFIG_LOG_IMMEDIATE=n
CONFIG_USE_AT_HOST=n

And I added to the spm.conf:

CONFIG_SERIAL=n

I tested the application and it worked fine. The Thingy 91 was sending sensor data to the nRF Cloud every 300 s (5 minutes).

Then I measured the current consumption with an advanced digital multimeter (Keysight 34465A) and got an average current consumption of 6.5 mA, which is way more than I expected.

I decided to turn off the UI module in prj_thingy91_nrf9160ns.conf:

CONFIG_USE_UI_MODULE=n

After this, I can't connect to the nRF Cloud. Nothing happens when I turn on the Thingy 91 and wait for 15 minutes. I tried it several times and reopened the nRF Cloud.

Any ideas why the application doesn't work with disabled UI module? And what can I do to reduce power consumption of the asset tracker application?

I use ncs version 1.4.0 and modem firmware version 1.2.2.

[Hakon]

Hello,

you can try removing the entire src/ui folder from asset tracker, and rebuild.

[andrew926]

First 12 seconds (y unit Ampere, x unit seconds):

Zoomed in between seconds 8 and 9:

The duration of a 40-50 mA peak is about 0,02 seconds. What could it be and how can I turn it off? As far as I know, the sensors do not consume so much power. There is also 1 mA current consumption in between the 40-50 mA peaks, which is much. Where could it come from?

This current was measured with Keysight 34465A before I removed src/ui. I also measured the current with a cheap multimeter at home.

The results of the cheap multimeter measurements were the same after I removed src/ui. I haven't measured the current with Keysight 34465A after I removed src/ui because at the moment I don't have access to it.

[andrew926]

I did the plot with 3000 measurements per second and got an average current (calculated by multimeter) of 6.5 mA.

[Hakon]

The spikes are probably from DRX events. It probably doesn't enter PSM properly.

[andrew926]

Could you measure the current and tell me if you get the same result, so that I can know whether the problem is in the code or it's the network in my country. I posted a download link to the project in a previous message.

[andrew926]

You are right, the spikes are from DRX events. I finally learned that PSM RAT should not be "11100000". I have set RAT to "00000000" and the spikes are gone! "11100000" means, RAT timer is deactivated, so RRC Idle (DRX) would go forever. I thought DRX would be deactivated.