Square wave generator using AR9331 hardware timer.
gpio-sqwave is an OpenWRT kernel module which provides square wave output on any AR9331 SoC GPIO pin with up to 125 kHz frequency.
##Installation
insmod gpio-sqwave [timer=0|1|2|3]
Default is timer 3
##Usage
Start: echo "<GPIO> <freq>" > /sys/kernel/debug/sqwave
"GPIO" is GPIO number, "freq" is square wave frequency in Hz. Maximum frequency with 200 MHz system bus (default clock) is 125 kHz; high settings may result in performance penalty or watchdog reset.
Example: to blink Black Swift's system LED with 1 Hz frequency: echo "27 1" > /sys/kernel/debug/sqwave
Stop: echo - > /sys/kernel/debug/sqwave
Status: echo ? > /sys/kernel/debug/sqwave
Check http://www.black-swift.com/wiki for more information.