Stealth mode

Stealth mode will turn off all but the Digital LEDs at once. It is implemented via a GPIO and a transistor, which means it won’t harm the Blade functionality. It is possible to change the brightness using software PWM however in some cases, it may not work perfectly.

Compute Blade RC2 cannot turn off the LEDs on the Ethernet port this way, but they can be turned off in other ways. The Digital LEDs will also not be turned off due to technical limitations, but since they are controlled from the GPIO this should not be a problem.\

Initialization in the terminal:

echo "21" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio21/direction

To turn off the LEDs:

echo "1" > /sys/class/gpio/gpio21/value

To turn on the LEDs:

echo "0" > /sys/class/gpio/gpio21/value

To do this immediately after booting the OS, you can add these commands to /etc/rc.local:

sudo nano /etc/rc.local

#!/bin/sh -e
#
# rc.local
#

echo "21" > /sys/class/gpio/export
sleep 0.1
echo "out" > /sys/class/gpio/gpio21/direction
echo "1" > /sys/class/gpio/gpio21/value
sleep 0.1

exit 0

To switch off LEDs on the Ethernet port add these lines to /boot/config.txt (Source)

#disable ethernet port LEDs
dtparam=eth_led0=14
dtparam=eth_led1=14