Which circuit to use to automatically turn off the backlight of a GLCD after 30s?
Oh, you could use something like the below, but the micro would be a more elegant solution for sure. You can play with the value of R1 to get closer to the 30s if it matters. 

If you use a CMOS 555 then you can use a lower value capacitor and higher value resistor. 

This will directly drive up to about a 100mA backlight. If you need more current, add a p-channel logic level MOSFET and you can drive a blindingly bright light. 







simulate this circuit &ndash; Schematic created using CircuitLab