i.MX8m-mini-bb EVK Power Consumption

[JamesShih]

Hi,

The power consumption on my i.MX8m-mini-bb EVK in CPUs idle state is ~325mA and suspend state is ~98mA.

My setup is

1. Set governor to powersave (CPUs in 200MHz)

2. Not connect to any peripheral on header Pins.

3. Use a USB-C meter attached in power side to check the current drain.

I used stress-ng to check the governor in different state and also killed the CPUs to ensure my setup are all correct, but no matter how I tried, I always got such high current drain while in the IDLE and SUSPEND states.

Is there any suggestion for me to try? and/or any power number for me as the reference on this board?

Thanks.

James Shih

[JamesShih]

Hi Chavira,

Thanks for your quickly response, I knew and reviewed this document, but my measured power number is higher than the datasheet number, that is why I'm asking here.

I used the IDLE_DEFAULT, roughly VDD_SOC_DRAM took ~245mA, but I got ~325mA, and in the suspend state, the datasheet number is < 20mA, but I got ~98mA, everything is in default, not attached anything.

Any recommendation?

Thanks.

James Shih

[Chavira]

HI @JamesShih!

Can you describe the procedure that you are following to obtain your results?

What revision of the board do you have?

What BSP version are you using?

[JamesShih]

Hi Chavira,
This is the SDK I used.
repo init -u https://github.com/nxp-imx/imx-manifest -b imx-linux-styhead -m imx-6.12.3-1.0.0.xml

The board I'm using is i.MX8m-mini-bb EVK (SCH-31407 REV E).

Everything default, only add opp table for the CPU clocks and enable the stress-ng.

[Chavira]

Hi @JamesShih!

Can you share the patch to review it by my side?

Can you try with the pre-compiled image to discard the customized image?

[JamesShih]

Hi Chavira,

I downloaded the pre-compiled image and programmed to my imx8m-mini-bb evk, unfortunately the result of the power consumption in idle and suspend modes are similar to my built images. (in fact the pre-compiled image has a bit higher current drain than mine)

Regarding my test steps, I didn't have any patch, I just setup the codebase, built and run, following are my steps.

Step1:

$ repo init -u https://github.com/nxp-imx/imx-manifest -b imx-linux-styhead -m imx-6.12.3-1.0.0.xml
$ repo sync

Step2:

$ DISTRO=fsl-imx-xwayland MACHINE=imx8mmevk source imx-setup-release.sh -b build
$ bitbake imx-image-core

Programmed the built image (wic.zst file to the emmc), boots and check the power consumption.

Here is my EVK setup, check the power from the USB-C meter.

[Chavira · Accepted solution]

HI @JamesShih!

I can see the misunderstanding here.

You are measuring the current consumption of whole board, and in the AN12410 we only measure the current consumption of the SOC.

According to the APP NOTE:

3.5. Measuring points on EVK platform
To measure the power consumption, do the rework first. Split the connection between the PMIC and CPU, and then solder a 0.025 Ω sensor resistor in series. The power data is obtained by measuring the average voltage drop over the measurement points and dividing it by the resistor value to determine the average current. The tolerance of the 0.025 Ω resistors you use should be 1 % or less. The measuring points for the various supply domains are as follows

• VDD_ARM: A53 Arm complex current for low-power measurements. The resistance value is
0.025 Ω.

• VDD_SOC: Chip domain current for SOC. The recommended resistance value for this
measurement is 0.025 Ω.

• VDD_GPU_VPU_DRAM: Chip domain current for GPU, VPU and DRAM. The recommended
resistance value for this measurement is 0.025 Ω.

• LPDDR4 I/O plus memory: Current in this domain includes the NVCC_DRAM current and the
overall current of the on-board LPDDR4 memory device. The recommended resistance value for this measurement is 0.025 Ω.

[Chavira]

HI @JamesShih!

Thank you for contacting NXP Support!

Please refer to our Application Note AN12410, where we detail the results and procedures for measuring current consumption on the iMX8MM-EVK board.

Best Regards!

Chavira