I modified the asset tracker application as follows (to reduce power consumption):
1) Added lte_lc_psm_req(true); at the end of main-function. In prj_thingy91_nrf9160ns.conf I set CONFIG_LTE_PSM_REQ_RPTAU="00100001" (1 hour) and CONFIG_LTE_PSM_REQ_RAT="00000000" (0 sec).
2) Deleted src/ui folder and commented out every #include "ui.h", ui_led_set_color and ui_led_set_pattern in main.c and gps_controller.c.
In prj_thingy91_nrf9160ns.conf, I commented out #CONFIG_USE_UI_MODULE=n, #CONFIG_NRF_CLOUD_LOG_LEVEL_DBG=n, #CONFIG_NRF9160_GPS_LOG_LEVEL_DBG=n, #CONFIG_CONSOLE_GETCHAR=n, #CONFIG_AWS_FOTA_LOG_LEVEL_DBG=n, #CONFIG_AWS_JOBS_LOG_LEVEL_DBG=n.
In Kconfig, I commented out #rsource "src/ui/Kconfig".
In CmakeLists.txt I commented out #src/ui and #add_subdirectory(src/ui).
3) Added BSEC Library to ncs/v1.4.0/nrf/ext, in prj_thingy91_nrf9160ns.conf I set CONFIG_BME680=n and CONFIG_USE_BME680_BSEC=y, in bsec.c I set #define BSEC_SAMPLE_RATE BSEC_SAMPLE_RATE_ULP.
4) Set environment data send interval and mqtt keepalive to 300 sec: CONFIG_ENVIRONMENT_DATA_SEND_INTERVAL=300 and CONFIG_MQTT_KEEPALIVE=300.
5) Disabled Light sensor and color sensor: CONFIG_LIGHT_SENSOR=n and CONFIG_BH1749=n.
6) Commented out every RSRP related code in main.c, because I don't need RSRP Info messages.
8) Disabled logging:
in prj_thingy91_nrf9160ns.conf I set CONFIG_LOG=n, CONFIG_LOG_IMMEDIATE=n, CONFIG_SERIAL=n, CONFIG_USE_AT_HOST=n, CONFIG_UART_CONSOLE=n, CONFIG_CONSOLE_HANDLER=n, CONFIG_CONSOLE_SUBSYS=n
and commented out #CONFIG_NRF_CLOUD_LOG_LEVEL_DBG=n, #CONFIG_NRF9160_GPS_LOG_LEVEL_DBG=n, #CONFIG_CONSOLE_GETCHAR=n, #CONFIG_AWS_FOTA_LOG_LEVEL_DBG=n, #CONFIG_AWS_JOBS_LOG_LEVEL_DBG=n.
After these modifications, everything works perfectly: the Thingy 91 connects to NRF cloud and sends environment data every 5 minutes (300 sec). It enters PSM, when it is not sending data.
I measured the power consumption with a digital multimeter. During PSM, the current is about 600 µA. Why? (I expect a floor current below 50 µA. According to nrf9160 specification, PSM floor current should be 2.7 µA.)
