./load_pwm.sh 
vi pwm.c
echo -n -e "\377" > /dev/pwm0
echo -n -e "\000" > /dev/pwm0
echo -n -e "\000" > /dev/pwm1
echo -n -e "\377" > /dev/pwm1
halfway is 177 or 177+1 = 200

vi irq.c
rmmod irq
make
(or make irq.o)
insmod ./irq.o
cat /proc/interrupts