Pi B+ - Disabling LEDs

You can turn the Red power LED off with

$ gpio -g mode 35 out $ gpio -g write 35 0

And you can disable the Green ACT LED with:

# echo none > /sys/class/leds/led0/trigger $ gpio -g mode 47 out $ gpio -g write 47 0

Use whatever you need to poke the gpio pins if you don't have wiringPi installed to get the gpio command.

-Gordon

Full scematics for B+ are not released yet.

The power LED seems to be driven by the reset line (i.e. will be extinguished if the microprocessor is held in reset because the supply voltage is out of range). So there is no software control over this.

The ACT LED is on part of the schematics not yet released. On the previous model B, it's driven by GPIO16, which is presumably driven by the sdcard driver. On the B+, GPIO16 is brought out to the extended GPIO connector, so it may be that the ACT LED is now driven from a different GPIO line, but is presumably still under the control of the sdcard driver. You could conceivably disable this one by modifying the driver so as not to use it.

There are also two LEDs in the ethernet connector.

It is software controllable. See my earlier post. The power LED is driven from the output of a low-voltage sensing chip - it will turn the LED off at 4.63v. That signal also goes to a GPIO pin and there is enough goodness there that if you turn that pin into an output and drive it, it won't damage anything, but you can control the LED. (Which is somewhat surprising, but often the case on many devices to indicate something other than just power - e.g. fault, etc.)

Disable or change its action through the /sys/class/leds/led0/trigger file. Find out its pin number by looking at /proc/cmdline - and also note that it was inverted in the A/B rev 1, 1.2 and 2, but the right way in the B+ (ie. connected to Vcc or 0V respectively)

From /proc/cmdline on a newish system:

bcm2708.disk_led_gpio=47 bcm2708.disk_led_active_low=0

Not sure you can control these - they are on "GPIO" pins on the USB/Ether chip, but how to control that ... Maybe if you hacked the kernel USB and/or ethernet driver...

Gordon

Desoldering works just fine. BTDT.

Paul