Raspberry PWM LED Control
We'll use GPIO 24/ Pin 18 to drive the LED as in the default configuration of rc-dukes.
We are going to use the Servoblaster software see Self_Driving_RC_Car#Servo Interface - Servoblaster
cat /run/servoblaster.status p1pins=7,11,12,13,15,16,18,22 p5pins= Servo mapping: 0 on P1-7 GPIO-4 1 on P1-11 GPIO-17 2 on P1-12 GPIO-18 3 on P1-13 GPIO-27 4 on P1-15 GPIO-22 5 on P1-16 GPIO-23 6 on P1-18 GPIO-24 7 on P1-22 GPIO-25
GPIO 24 has Servoblaster Id 6 so
echo 6=120 > /dev/servoblaster
will set the LED to half bright