Current measurement for a Nordic Thingy 91 device

[Adeel]

Hi Dev Zone Team,

I had a question regarding the current measurement of Nordic Thingy 91. I am following the steps provided in the Thingy91 documentation. 

I have a Joulescope (https://www.joulescope.com/) for the current measurement and viewing. 

I have cut the SB3 Jumper and wish to connect the Vdd and GND pins. I have also deattached the battery.

I wanted to know the voltage to be applied at the VDD_nRF91 pin and if possible a connection picture.

I have attached the schematic that I was following for reference and also my module that I wish to measure.

. 

Thanks :).

[helsing]

Hi Adeel,

Are you measuring the current consumed by the whole thingy, or are you interested in the current consumed by nrf91 itself?

Please see the notes on Low Power in the README.rst of the asset_tracker application(assuming you are on NCS v1.3.0). Using PSM or eDRX mode will help you save power.

I have updated my previous message with the link that was missing.

Best regards,

Håkon

[Adeel]

Hi Hakon,

I am trying to measure the whole thingy power here. Yes, I am on NCS v1.3.0.

Also, I have read it on some blog here that for some applications, the CONFIG_SERIAL = n also helps in reducing the power as it disables the Serial comm. Does this also apply to the asset tracker application ?  

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/measuring-psm-sleep-current-on-the-nrf9160-dk

This is the blog post and I am integrating the code in the above blog into my asset tracker application, but I dint find any CONFIG_SERIAL = n option in the prj.conf file in the asset tracker app.

I wanted to know if there is a way to disable the serial comm just to see the minimum power consumption of my thingy in this case.

Thanks

[helsing]

Hi Adeel,

It should be possible to just add CONFIG_SERIAL=n to the prj.conf file.

prj.conf is not used for defining configs but for using already defined configs from Kconfig. In NCS v1.3.0 you will find CONFIG_SERIAL in Zephyr/drivers/serial/Kconfig:6 .

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.3.0/kconfig/CONFIG_SERIAL.html#cmdoption-arg-config-serial

I will get back go you regarding more ways to save power.

Best Regards,

Håkon

[Adeel]

Hi Hakon,

I tried to add CONFIG_SERIAL = n into my prj.conf file but the build failed as I got errors in the UART.h file. Its mainly with the uart_irq_rx_enable/disable/update function. 

Any idea about this could be tackled with as I have observed that there is a significant power reduction when disabling UART and I wanted to try that.

Regards,

Adeel.

[Adeel]

date_time_master.rar

I am attaching my working file here. Could you try to run it and verify the error I am getting here above. I have disabled the CONFIG_SERIAL = n option both in spm.conf as well as prj.conf here. 

I also tried to tried to add the overlay file to disable the UART but it dint work. Could you try and help me out by running my code at your end .

Regards,

Adeel.

[Adeel]

Hi,

Any update on this thread ? 

Regards,

Adeel.

[Stian Røed Hafskjold]

Hi, I did some measurements on your code, and the problem is that AT_HOST is using UART. So it will fail to compile if you remove the UART instances using CONFIG_SERIAL=n. To make it compile, comment out the # AT Host section in prj.conf. (CONFIG_UART_INTERRUPT_DRIVEN and CONFIG_AT_HOST_LIBRARY).

Now the code compiles and the sleep current is 4 uA. Your code seems to wake up every 1250 ms, and the average current including the wakeup is 30 uA.