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Monday 23 December 2013

Overview of power switch options for the Raspberry Pi [day 13 of 20-days-of-posts series]

A power switch was omitted in the design of the Raspberry Pi to keep costs down.  There was no easy interface provided to add one either, but there are many different options.  I had previously tackled the original topic in a previous post, comparing a few options, including building your circuit.

Challenge:  The Raspberry Pi always remains powered-on as long as there is power coming in on the micro-USB power line.  A shutdown/halt/poweroff command will shutdown the OS and leave the system in a powered on but idle state.  The power consumption would be unchanged between idle and active on the Raspberry Pi.  Further, to turn the system back on, the USB cable needs to be unplugged or the power supply needs to be unplugged (reset).

Ideally we need....

  • something that powers the raspberry pi off when it is shutdown (power consumption becomes negligible / < 0.5 W) [POWER OFF]
  • something that can trigger a clean software shutdown [CLEAN SHUTDOWN]

Over the past few months since the  original topic / post, I've covered the following options:
I've felt it was time to do a head-to-head comparison of the five options that were discussed in the previous posts.

Assumptions:

  • all values are in USD; shipping costs and taxes are excluded throughout 
  • measurements are based on a scale of 1 - 5
Build Your Own Circuit USB Big Red Button illuminated /
rocker-style
by Mausberry Circuits
WeMo Switch by Belkin RemotePi Board
by MSL Digital Solutions
Product Page n/a link illuminated switch
rocker switch
generic USB switch
custom switch
WeMo RemotePI
Price varies based on parts
($ 5 - $ 40)
$ 1 - $ 7 $ 14 - $ 16 $ 50 $ 24 - $ 27
Integration  bulky setup plug into free USB port
3 jumper wires hooked upto GPIO
plug Pi USB power plug into locks onto GPIO
Easy of Hardware Setup  1 / 5
- soldering required
5 / 5
- plug-and-play
- solder-free

4 / 5
- risk of causing damage if you place the cables on the wrong pins
- solder-free

5 / 5
plugs in
5 / 5
- plugs in, screws on
- solder-free
Easy of Software Setup 

1 / 5
- requires writing your own app
2 / 5
requires installing apt-get packages, compiling and provided C code
/ 5
- run switch.sh install
- default script had issue causing crashing Pi, some modification needed to code
2 / 5
- requires phone app
- firmware and app buggy
4 / 5
- run irswitch.sh install
- program power button on remote
- setup lird.conf for remote
Reset Button
[hard reset]?
DEPENDS
if intercepts power source
NO iluminated switch NO
rocker switch YES
NO NO
Safe Shutdown? YES YES YES NO
(use some thought process around shutdowns)
YES
Power Consumption
[as measured by a kill-a-watt
negligible  negligible negligible 1.5 - 2.5 W
just as much power as the Pi!
negligible
Completely Powers off Pi? DEPENDS
if intercepts power source
NO YES YES YES
Powers Pi by GPIO, micro USB or USB (Pi rev B)n/a micro USB via micro USB micro USB or USB port (Pi rev B) GPIO via micro USB
Shutdown Scripts
device driverRaspBMC/Raspbian/Debian
OpenELEC
Arch
n/aOpenElec
RaspBMC
XBian
Major Selling Features - switches can be used for other purposes- switches can be used for other purposes - select models include reset switch
- rocker switch (left in on position) works with well WeMo to power on remotely
- power on Pi using different conditions
- remote power on / off / reboot
- includes IR receiver for XBMC
- only solution that can power on Pi via IR
Full Review previous post previous post previous post previous post previous post
My Sample Integration n/a n/a rocker switch
illuminated switch
n/a RemotePi

1 comment:

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