DART-6UL WakeableGPIO

DART-6UL - Wakeable GPIO

\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 */

Reboot the system

Reboot the system and wait for a login prompt

$ reboot 

Enter memory retension

After this command the system will enter memory retension mode.
The serial console will stop responding, all not needed power supplies will be shut down. You can see that LEDs D30, D27 will turn off on the EVK.

$ 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 PWR button to wake up the system.