mikerr
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Pi 3B+ low power consumption

Fri Mar 16, 2018 2:03 pm

Playing with power consumption of the new 3B+ - here's some numbers

Pi powered via GPIO and measurements from the bench PSU

Latest Raspbioan image installed, and connected to wifi (nothing else)

After bootup it idles at 435 mA with wifi connected, or 380 mA with ethernet connected

Stressing the CPU makes it jump to 610 mA

Saving power:

As usual you can save ~20mA by turning off HDMI:

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sudo tvservice --off
Turning off USB power drops off a further ~200 mA down to 195 mA

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echo 0 | sudo tee /sys/devices/platform/soc/3f980000.usb/buspower >/dev/null
Note you lose USB peripherals and ethernet in that case, but usefully WiFi is still active as its connected via SDIO

So 195 mA is the lowest usable power IMO

We can go lower though:

Turning off the wifi :

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sudo ifconfig wlan0 down
142 mA !

Image
Last edited by mikerr on Fri Mar 16, 2018 9:45 pm, edited 1 time in total.
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PiGraham
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Re: Pi 3B+ low power consumption

Fri Mar 16, 2018 2:12 pm

So for 142mA (0.7W) you get GPIO and audio? That would be usable for some things.

mikerr
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Re: Pi 3B+ low power consumption

Fri Mar 16, 2018 2:16 pm

Yes, GPIO and audio still active there.

Since this is all done with runtime commands, you can "go to sleep" down to 142 mA and wake up all the peripherals back to 450 mA+ as needed within a couple of seconds.
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fred44nl
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Re: Pi 3B+ low power consumption

Fri Mar 16, 2018 2:20 pm

is there a way to turn off HDMI, Bluetooth and Wifi permanently ??
headless RPi 3B running from usbhdd.

W. H. Heydt
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Re: Pi 3B+ low power consumption

Fri Mar 16, 2018 2:34 pm

fred44nl wrote:
Fri Mar 16, 2018 2:20 pm
is there a way to turn off HDMI, Bluetooth and Wifi permanently ??
Put the commands to do so in various files that are run at startup.

fanoush
Posts: 454
Joined: Mon Feb 27, 2012 2:37 pm

Re: Pi 3B+ low power consumption

Fri Mar 16, 2018 3:00 pm

mikerr wrote:
Fri Mar 16, 2018 2:03 pm
Turning off USB power drops off a further ~200 mA down to 195 mA

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echo 0 | sudo tee /sys/devices/platform/soc/3f980000.usb/buspower >/dev/null
I wonder if you can turn off just the ethernet usb device while keeping usb hub up?
200mA is quite a lot for idle USB with nothing attached.

tkaiser
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Re: Pi 3B+ low power consumption

Fri Mar 16, 2018 4:23 pm

fanoush wrote:
Fri Mar 16, 2018 3:00 pm
I wonder if you can turn off just the ethernet usb device while keeping usb hub
Nope, since it's cutting power to the Microchip IC.

Since not already mentioned: The type of Ethernet connection and the mode with Gigabit Ethernet (EEE or not) are also important: viewtopic.php?f=63&t=207863&start=150#p1285936

Gigabit Ethernet vs. Fast Ethernet as usual makes a real difference in case the switch at the other end of the Ethernet cable does not also support EEE: https://en.wikipedia.org/wiki/Energy-Efficient_Ethernet

Switching between both speeds is easy (and can be done even over SSH, it just takes 1-3 seconds until you can continue):

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ethtool -s eth0 speed 100 duplex full # Fast Ethernet
ethtool -s eth0 speed 1000 duplex full # Gigabit Ethernet

mikerr
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Re: Pi 3B+ low power consumption

Fri Mar 16, 2018 4:30 pm

fanoush wrote:
Fri Mar 16, 2018 3:00 pm
I wonder if you can turn off just the ethernet usb device while keeping usb hub up?
Not as such, but

Code: Select all

sudo ifconfig eth0 down
saves around 40 mA even without rj45 connected.
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fred44nl
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Re: Pi 3B+ low power consumption

Sat Mar 17, 2018 11:28 am

W. H. Heydt wrote:
Fri Mar 16, 2018 2:34 pm
fred44nl wrote:
Fri Mar 16, 2018 2:20 pm
is there a way to turn off HDMI, Bluetooth and Wifi permanently ??
Put the commands to do so in various files that are run at startup.
and in what files could that be ??
or is there another method ??
headless RPi 3B running from usbhdd.

mikerr
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Re: Pi 3B+ low power consumption

Sat Mar 17, 2018 11:37 am

I found the command

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sudo rfkill block all
actually turns off both wifi and bluetooth permenantly across reboots

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sudo rfkill unbliock all
to get them back.
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fred44nl
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Location: Scharendijke, NL

Re: Pi 3B+ low power consumption

Sat Mar 17, 2018 11:40 am

mikerr wrote:
Sat Mar 17, 2018 11:37 am
I found the command

Code: Select all

sudo rfkill block all
actually turns off both wifi and bluetooth permenantly across reboots

Code: Select all

sudo rfkill unbliock all
to get them back.
thank you, but I don't have rfkill as a command.
headless RPi 3B running from usbhdd.

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DougieLawson
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Re: Pi 3B+ low power consumption

Sat Mar 17, 2018 11:40 am

sudo apt install rfkill
Note: Having anything remotely humorous in your signature is completely banned on this forum.

Any DMs sent on Twitter will be answered next month.

This is a doctor free zone.

mikerr
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Re: Pi 3B+ low power consumption

Sat Mar 17, 2018 11:47 am

Its already installed in stretch desktop, maybe not in lite ?
other methods of disabling wifi/bt : viewtopic.php?t=138610
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fanoush
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Re: Pi 3B+ low power consumption

Mon Mar 19, 2018 11:31 am

mikerr wrote:
Fri Mar 16, 2018 4:30 pm
fanoush wrote:
Fri Mar 16, 2018 3:00 pm
I wonder if you can turn off just the ethernet usb device while keeping usb hub up?
Not as such, but

Code: Select all

sudo ifconfig eth0 down
saves around 40 mA even without rj45 connected.
What I meant is something like https://gist.github.com/Robpol86/5894185 that you could do with previous Pi. This disables that specific ethernet device on the usb bus (write to /sys/bus/usb/drivers/smsc95xx/unbind) while keeping the usb hub up. Not sure how much it saved exactly but it did make difference for me in specific case with limited power.

fanoush
Posts: 454
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Re: Pi 3B+ low power consumption

Mon Mar 19, 2018 10:07 pm

fanoush wrote:
Mon Mar 19, 2018 11:31 am
What I meant is something like https://gist.github.com/Robpol86/5894185 that you could do with previous Pi. This disables that specific ethernet device on the usb bus (write to /sys/bus/usb/drivers/smsc95xx/unbind) while keeping the usb hub up.
I just tried it with Pi3 (not +) and the power draw with ethernet cable removed is mostly the same in all three cases - interface up, down and when device is unbound as mentioned above. The only difference of unbinding is is that there is no eth0 device at all.

However what brought it down for me by 50mA is deconfiguring usb device i.e. write 0 to bConfiguration value of device 1-1.1 with idVendor/idProduct 0424/ec00

evilkitty
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Re: Pi 3B+ low power consumption

Mon Mar 19, 2018 11:04 pm

fred44nl wrote:
Fri Mar 16, 2018 2:20 pm
is there a way to turn off HDMI, Bluetooth and Wifi permanently ??
I have this in /etc/rc.local:

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/usr/bin/tvservice -o
as well as this in my /boot/config.txt

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# Disable wireless chip on Pi3
dtoverlay=pi3-disable-wifi,pi3-disable-bt
I also turned off some bluetooth services

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sudo systemctl disable bluetooth
sudo service bluetooth stop
sudo systemctl disable hciuart
sudo service  hciuart stop
hciuart has to do with bluetooth modems and bluetooth is the daemon for bluetooth
My Pi Server: http://imgur.com/a/6xIUI | Thermostat: http://imgur.com/a/4LVnT

fanoush
Posts: 454
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Re: Pi 3B+ low power consumption

Thu Mar 22, 2018 9:44 pm

I finally received 3b+ today :-) One interesting fact related to USB -
There are now two usb hubs! First hub has ethernet and pair of two USB ports next to it and second hub has the other two ports.
here is lsusb -t with mouse in one pair and keyboard in second

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/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc_otg/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 1: Dev 3, If 0, Class=Hub, Driver=hub/3p, 480M
            |__ Port 1: Dev 9, If 0, Class=Vendor Specific Class, Driver=lan78xx, 480M
            |__ Port 3: Dev 10, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 3: Dev 10, If 1, Class=Human Interface Device, Driver=, 1.5M
        |__ Port 2: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 2: Dev 4, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M

And here is when I move mouse above keyboard to same pair

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/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc_otg/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 1: Dev 3, If 0, Class=Hub, Driver=hub/3p, 480M
            |__ Port 1: Dev 9, If 0, Class=Vendor Specific Class, Driver=lan78xx, 480M
        |__ Port 2: Dev 4, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 2: Dev 4, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 11, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 11, If 1, Class=Human Interface Device, Driver=, 1.5M
And what is interesting is that the nested 3port hub can be turned off separately. And the power draw is even lower than just with ethernet off. Ethernet off makes 50mA difference and whole hub another 70mA - total 120mA difference.

Code: Select all

[email protected]:/sys/bus/usb/devices# echo 0 > 1-1.1.1/bConfigurationValue
[email protected]:/sys/bus/usb/devices# echo 0 > 1-1.1/bConfigurationValue
Now ports next to ethernet are dead but second pair with mouse and keyboard works! And power draw is now only a bit higher than 3B.

And BTW that is why https://www.microchip.com/wwwproducts/P ... 15/LAN9514 page says 6 downstream ports. It is one 4port hub with 3port hub attached to it. So looks like there are two more not connected ports 'available'.
EDIT:
Actually just one more port, ethernet is fifth. I wonder if this extra port is available somewhere.

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