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  1. Concept
  2. Power Measurements
    1. Processor Dependent Power Usage
    2. Peripheral Power Table
  3. How to Reduce Power
    1. IMX6 internal LDO (ldo-bypass vs ldo-enabled)
    2. Peripherals
    3. DVFS
    4. Reducing Cores
  4. Power Protection

Concept

A question we typically receive deals with power consumption of our product. Usually, these questions deal with power differentiating between typical operating power that we state on our products page and what the user is actually seeing. This page will try to detail what typical power usage means and our internal power measurements with various modes of operation and different types of hardware.

Power Measurements

The following "Power Table" shows our results for different processor configurations for our different products. Our "typical" power usage comes from our standard product, processor dependent power usage, as seen in this section below. The power differences between our BSP's is due to the fact that some drivers do not exist in one, and do in the other. Because of this, the BSP with more driver support has the ability to turn off certain components and save power that the other cannot.

Processor Dependent Power Usage

Each "delta" is based on our standard product at a linux prompt with the vendor kernel using the Yocto 1.8 BSP, which is bolded in the table below. To calculate a power estimate for a particular system configuration start with the lower power range found in this chart and then go down to the Peripheral Power Table and add the power numbers for each of the different peripherals to these base number. Note these are general guidelines and results can vary widely depending on the software running and system setup.

These are approximated values. Ranges show feasible min-max overall draws.

Processor Deltas GW5100 GW5200 GW5300 GW5400 GW5510 GW5520
i.MX6SOLO -.1W -.1W -.1W -.42W 1.32-3.95W -.1W
i.MX6DL .79-4W 2.85-4.7W 3.25-6.3W -.32W +.1W 2.23-4.8W
i.MX6Q +.23-3W +.1-3.4W +.5-3.7W 5.34-11.2W +.1-3W +.3-3W

If you wish to discuss a board with a cpu change from our standard product, please our sales department here.

Peripheral Power Table

The following table denotes power consumption based on peripheral use. The <==== symbol shows that the previous value holds in this place. An 'x' means that functionality does not exist on that particular board.

These are approximated values.

Peripheral Table GW5100 GW5200 GW5300 GW5400 GW5510 GW5520 Notes
OpenWrt Prompt (14.08) +1.1W +.31W +1.21W +.7W +.9W +1.07W Please see note 1; Delta is based on above Yocto values
100mbps Link +.11W <===== <===== <===== <===== <=====
1000mbps Link +.50W <===== <===== <===== <===== <=====
100mbps udp iperf client +.81W <===== <===== <===== <===== <=====
400mbps udp iperf client +1.18W <===== <===== <===== <===== <=====
OTG+4GB FLASH +.38W <===== <===== <===== <===== <===== Generic 4GB Flash Drive
HDMI Out +.18W <===== <===== <===== <===== <===== Please see note 2
HDMI In x x x +1W <===== x Please see note 3
HDMI In/Out x x x +1.3W <===== x Please see note 4
LVDS 0% x +.88W <===== <===== x x LVDS screen is connected, but blanked
LVDS Out (50%) x +1.85W <===== <===== x x Please see note 2
CVBS In +.34W <===== <===== <===== x x Please see note 3
CVBS In/Out +.64W <===== <===== <===== x x Please see note 4
CPU Active +1.62W <===== <===== <===== <===== <===== Please see note 5
GPU Active +1.03W +1.41W +1.5W +2.4W +.95W +1.01W Please see note 6
VPU Active +.55W <===== <===== <===== <===== <===== Please see note 7
Board Fully Stressed +3.2W +1.86W +3.06W +5.86W +2.63W +2.58W Please see note 8

1 Note that the GW5400 has the most components and thus has higher power cost compared to GW5300 etc since OpenWrt currently doesn't have driver support for all components on the board
2 gst-launch videotestsrc pattern=0 ! mfw_v4lsink device=/dev/video16
3 gst-launch tvsrc device=/dev/video0 ! fakesink
4 gst-launch tvsrc device=/dev/video0 ! mfw_v4lsink device=/dev/video16
5 stress --io 32 --cpu 32
6 export DISPLAY=:0.0; /opt/fsl-gpu-sdk/GLES2/S08_EnvironmentMappingRefraction/S08_EnvironmentMappingRefraction_X11
7 gst-launch-1.0 videotestsrc ! imxvpuenc_h264 ! queue ! imxvpudec ! fakesink
8 Used multiple instances of notes 5,6,7 to reach max current draw

For example, to estimate the power range for a GW5100 with an i.MX6DL Processor with Yocto BSP, using 1000mbps link with CVBS In, the estimated power usage would be 0.79W + .5W + .34W = 1.63W at the low end and then add 3.2W to this number if maximally stressed = 4.83W

How to Reduce Power

Reducing power is a very complex topic and widely variable.

Freescale has published documents on this topic at the following links:

IMX6 internal LDO (ldo-bypass vs ldo-enabled)

The IMX6 processor has several internal low dropout (LDO) regulators. Two of these regulate the VDD_ARM (power to the ARM cores) and VDD_SOC (power to everything else with the exception of the VPU and GPU). The voltage input to these LDO's comes from the Power Management IC (PMIC).

Based on these LDO's there are two modes of power operation that you can run the IMX6 in on Gateworks Ventana boards:

Gateworks has performed extensive testing on the various Ventana boards and in general has found the following:

For IMX6 SoC longevity information of ldo-bypass vs ldo-enabled please see the following NXP documents:

The Gateworks bootloader will determine if a kernel has ldo-bypass capability by examining its device-tree carefully prior to jumping to the Linux kernel and will by default (in our current bootloader and BSP's) boot in ldo-enabled mode. The most recent bootloader does have the ability to alter compatible device-tree's in order to boot in ldo-bypass mode if the 'ldobypass' env variable is set to 1. If users wish to run in ldo-bypass mode it is advised that they perform their own stability testing. Users should only consider ldo-bypass mode if they are stretching the limits in power consumption and/or thermal power.

Important notes:

Peripherals

The table above shows the power draw for many of the peripherals. By not using these, the power is thus reduced. Removing these peripherals on custom board is an option.

DVFS

DVFS can reduce the frequency of the processor and thus lower the power.

See more about Dynamic Frequency and Voltage Scaling

Reducing Cores

It is possible to schedule processes to specific cores on the processor. This load balancing can be helpful.

However, you cannot actually 'turn off' a core. Even if a process is not running on a core, the core is still powered up.

Power Protection

Note: below applies to Ventana boards except GW55xx and GW51xx

For the power input we have an input TVS for protection.

Here is the datasheet for the part (SMAJ58A is the part we use): Link Here

The actual DC/DC is rated to 100V input and the FETs to 80V so we have plenty of headroom and have not had any issues with customers running the boards off auto power. We also have a series diode in the power path which protects against reverse voltage dumps.

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