Switch display backlight off for power saving

[letsfindaway]

Most probably the display backlight is the biggest power consumer of the system.

For power saving we might consider to switch the display backlight off after e.g. 3 minutes of inactivity on the touch screen. We will switch it on again on the first touch detected.

[letsfindaway]

Switching the backlight can be acomplished by using GPIO2 of the touch controller. This can be accessed using the low level interface routines of the controller.

Initialization:

// define both GPIO2 and GPIO3 as outputs
TS.writeRegister8(SPME_GPIO_DIR, 0x0c);
// initially switch on the backlight
TS.writeRegister8(SPME_GPIO_SET_PIN, 0x04);

Switch on and off:

// switch on the backlight
TS.writeRegister8(SPME_GPIO_SET_PIN, 0x04);
// switch off the backlight
TS.writeRegister8(SPME_GPIO_CLR_PIN, 0x04);