4700 Backlight Control
From embeddedTS Manuals
A PWM signal on this line is used to control the brightness of the LCD backlight. In the ts4700.subr file we implement several commands for controlling this backlight.
backlight_on() backlight_off() backlight_low() backlight_medium() backlight_high()
See #DIO for more information on MFP_85 and the CPU GPIO.