구차니의 잡동사니 모음

 idle + lan + hdmi

 2.50

 idle + lan

 2.45

 idle + hdmi

 2.23

 idle

 2.22

#!/bin/bash

#Code to stop

/etc/init.d/networking stop

echo 0 > /sys/devices/platform/bcm2708_usb/buspower;

echo “Bus power stopping”

#!/bin/bash

#Code to start

echo 1 > /sys/devices/platform/bcm2708_usb/buspower;

echo “Bus power starting”

sleep 2;

/etc/init.d/networking start 

This tip has been suggested by many people. If your system is headless (no video output) you can turn off the HDMI port with:

sudo /opt/vc/bin/tvservice -o

to turn it back on:

sudo /opt/vc/bin/tvservice -p

This command will save you around 20-30mA. 

$ chcpu

Usage:

 chcpu [options]

Options:

  -h, --help                    print this help

  -e, --enable <cpu-list>       enable cpus

  -d, --disable <cpu-list>      disable cpus

  -c, --configure <cpu-list>    configure cpus

  -g, --deconfigure <cpu-list>  deconfigure cpus

  -p, --dispatch <mode>         set dispatching mode

  -r, --rescan                  trigger rescan of cpus

  -V, --version                 output version information and exit 

$ sudo chcpu -r

chcpu: This system does not support rescanning of CPUs

$ sudo chcpu -e 2

chcpu: CPU 2 is not hot pluggable 

/sys/devices/system/cpu/cpufreq/ondemand $ cat up_threshold

50 

For example to disable cpu1:

echo 0 | sudo tee /sys/devices/system/cpu/cpu1/online

To re-enable:

echo 1 | sudo tee /sys/devices/system/cpu/cpu1/online

CPUs are numbered 0 to 3. You can not disable CPU0.

You can confirm in dmesg:

CODE: SELECT ALL

[86696.500790] IRQ93 no longer affine to CPU1

[86696.501155] CPU1: shutdown

CODE: SELECT ALL

[86968.395163] CPU1: Booted secondary processor

You should be able to set CPU frequency with 'cpufreq-set' (example for 1Ghz):

CODE: SELECT ALL

sudo cpufreq-set -f 1000000

# Disable VPU (Video decoding engine, Saves RAM!!!)

# 0 = disabled

# 1 = enabled

setenv vpu "1"

# Disable HDMI Output (Again, saves ram!)

# 0 = disabled

# 1 = enabled

setenv hdmioutput "1" 

$ sudo chcpu -d 1,2,3

CPU 1 disabled

CPU 2 disabled

CPU 3 disabled

Can I build a commercial product based on Arduino?

Yes, with the following conditions:

• Physically embedding an Arduino board inside a commercial product does not require you to disclose or open-source any information about its design.
• Deriving the design of a commercial product from the Eagle files for an Arduino board requires you to release the modified files under the same Creative Commons Attribution Share-Alike license. You may manufacture and sell the resulting product.
• Using the Arduino core and libraries for the firmware of a commercial product does not require you to release the source code for the firmware. The LGPL does, however, require you to make available object files that allow for the relinking of the firmware against updated versions of the Arduino core and libraries. Any modifications to the core and libraries must be released under the LGPL.
• The source code for the Arduino environment is covered by the GPL, which requires any modifications to be open-sourced under the same license. It does not prevent the sale of derivative software or its inclusion in commercial products.

In all cases, the exact requirements are determined by the applicable license. Additionally, see the previous question for information about the use of the name “Arduino”.