DART-6UL WakeableGPIO
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 PWR button to wake up the system.