Wireless MCUのトピックRe: KW41 Thread Low Power End Device test

KW41 Thread Low Power End Device test

wswong — Tue, 08 Aug 2017 11:12:22 GMT

Dear Experts,

Customer tested the Thread Low Power End Device Project in SDK 2.2 their KW41 module board. Attached is the project code (SDK_2.2_FRDM-KW41Z_Thread_IAR.7z) which they use and downloaded from MCUXpresso SDK Builder. The project is located in the below path:

\boards\frdmkw41z\wireless_examples\thread\low_power_end_device\freertos\iar\low_power_end_device_freertos.eww.

They modified the project as follow to setup for low power current measurement test;

#define gDCDC_Enabled 1 //please refer to the attachment picture (Enable_DCDC.png)
In app_init.c, comment out the App_Init() in main_task() to make the MCU enters low power mode shortly.

Then, they run the project and measure the current consumption of their board, the result show KW41 consumes about 5uA in average. However, there are some much higher current pulse happen periodically. Is that normal? Attached picture pulsesAfterSleep.png shows the measured result.

Would you please help comment why there are periodically high current pulse happen in between? How to remove those pulses in test?

Also, Is that possible and How to config KW41 to run in Low power Timer using an internal clock instead of using external 32KHz oscillator?

Thanks and Best Regards,

Re: KW41 Thread Low Power End Device test

gerardo_rodriguez — Tue, 08 Aug 2017 23:26:36 GMT

Hello Ws Wong,

I'm not able to see the attached files you are referring to. Can you re-upload them? I believe the pulses you are referring to are due to the DCDC refreshing.

Is the customer using the FRDM-KW41Z or a custom board?

You need the external 32KHz crystal for low power modes since the internal reference clock is OFF in LLSx modes.

Regards,

Gerardo

Re: KW41 Thread Low Power End Device test

wswong — Thu, 10 Aug 2017 08:29:31 GMT

Hi Gerardo,

Thanks for the information.

Customer is using their own module board with KW41. I re-upload the project for your double check.

Thanks and Best Regards,

Re: KW41 Thread Low Power End Device test

gerardo_rodriguez — Thu, 10 Aug 2017 22:55:46 GMT

Hello Ws Wong,

Are the images you are referring to included in the .zip file? I am not able to find them.

My recommendation is to make the same measurements on a FRDM-KW41Z and compare the results with the custom board.

For measuring low power current on buck mode, you need to consider point 3 of the document FRDM-KW41Z Development Platform Errata . Since there is a pull up resistor that can prevent measuring the low power datasheet numbers.

Regards,

Gerardo