DART-6UL WakeableGPIO

DART-6UL - Wakeable GPIO

In Suspend mode, The power domains of all pins of the SOM are switched off in memory retention mode => All GPIOs lose their state.
The only domain that remains alive is RTC domain (SNVS) and the only pins that still accessible are bank 5 of the GPIO.
The DART-6UL provides 4 external GPIO pins that are a part of bank 5, and can be used for waking the system up and for controlling external peripherals in sleep mode.

In teh below example we will use GPIO5_1 to wake up the system. This pin is exposed on J2.64 of the SOM and on pin J6.6 of the EVK.

Define GPIO as a key pad

Add the following section to the imx6ul-var-dart.dtsi file, right after leds section:

	gpio_keys {
		compatible = "gpio-keys";
		#address-cells = <1>;
		#size-cells = <0>;
		autorepeat;
		button@21 {
				label = "GPIO Key UP";
				linux,code = <103>;
				gpios = <&gpio5 1 1>;
				gpio-key,wakeup;
		};
	};

Add GPIO pad configuration

Add the following section to the imx6ul-var-dart.dtsi file, into pinctrl_hog_1 group:

MX6UL_PAD_SNVS_TAMPER1__GPIO5_IO01	0x1b0b0 /* WAKE gpio */

Enter memory retention mode

$ echo mem > /sys/power/state

Wake up the system

Connect pins J6.6 and J6,8 with a jumper. It will wake the system up.
You can also press the PWR button to wake up the system.