How to achieve the lowest power consumption on the Actinius Icarus (nrf9160) board?

[Nikil Rao]

Hi,

I'm trying to lower the power consumption om an Actinius Icarus board which uses an nrf9160 chip. I've been able to achieve a sleep current of 1.33mA and I'm not able to lower this any further. Could you please let me know what else I could do to lower the power consumption?

My setup - 

• Board - Actinius Icarus
• NRF Connect SDK - v1.2.0
• Modem FW - 1.1.1
• Sim - External NBIoT Sim card from 1nce which uses Deutsche Telekom band 8
• Antenna - Ethertronics penta 1002292
• Input - 4x1.5V batteries supplied to the Vin pin
• Current measurement - Multimeter inserted between batteries and Vin
• External peripherals - Using a 10k NTC with a 10k pullup voltage divider circuit connected to A1 for temperature measurement

Things done to reduce power consumption - 

1. Disabled logs in the project and SPM- 
   
   CONFIG_CONSOLE=n
   CONFIG_STDOUT_CONSOLE=n
   CONFIG_LOG=n
   CONFIG_SERIAL=n
   CONFIG_UART_CONSOLE=n


2. Enabled power management - 
   
   CONFIG_SYS_POWER_MANAGEMENT=y
   CONFIG_DEVICE_POWER_MANAGEMENT=y


3. Enabled PSM with these parameters (Also with different p-tau like 10 min, 1 hour, etc) 
   
   CONFIG_LTE_PSM_REQ_RPTAU="11000001"
   CONFIG_LTE_PSM_REQ_RAT="00000001"


4. Removed bootloader - 
   CONFIG_BOOTLOADER_MCUBOOT=n
   
   

The current drawn through the NTC voltage divider is around .16mA. I have connected to the AWS server via MQTT and send sensor data to the server at a fixed interval. I send the data and go to sleep for a defined time and repeat the process. I observe a constant sleep current of 1.3mA. When the device wakes up and sends data, I see spikes of 50mA and it comes back to 1.3mA after 2 seconds according to CONFIG_LTE_PSM_REQ_RAT.

For testing, I also edited the same project and made the device run an infinite while loop with a sleep function and still see that the sleep current is 1.3mA. From what I understand it looks like the modem does go to PSM (if I disable it I see a sleep current which keeps fluctuating between 1.3mA to 50mA). The sleep current with the modem switched off (with an AT+CFUN=0) command also shows me a sleep current of 1.3mA. This leads me to believe that there are some other peripherals which are switched on and consuming power. I'm not able to figure what else I should be doing at this point to lower the current consumption. Could you please advise me on  how to proceed? Thanks a lot!

Nikil

[Håkon Alseth]

Hi,

 

The sleep current with the modem switched off (with an AT+CFUN=0) command also shows me a sleep current of 1.3mA.

This indicates that there's a peripheral running in the background causing the high sleep current.

Instead of changing spm files directly, you can add this just below your application's CMakeLists.txt, the cmake_minimum_required() line:

if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/spm.conf")
  set(spm_CONF_FILE
    prj.conf
    ${CMAKE_CURRENT_LIST_DIR}/spm.conf
  )
endif()

 

if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/mcuboot.conf")
  set(mcuboot_CONF_FILE
    prj.conf
    ${CMAKE_CURRENT_LIST_DIR}/mcuboot.conf
  )
endif()

 

if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/${BOARD}.overlay")
  set(mcuboot_DTC_OVERLAY_FILE "${CMAKE_CURRENT_SOURCE_DIR}/${BOARD}.overlay")
  set(spm_DTC_OVERLAY_FILE "${CMAKE_CURRENT_SOURCE_DIR}/${BOARD}.overlay")
endif()

 

Then you create a file, spm.conf, with the content "CONFIG_SERIAL=n", and it should disable uart in spm.

 

What peripherals are you using in your application? TWIM/SPI/ADC?

 

Kind regards,

Håkon