DART-6UL suspend

Suspend to RAM

Suspend to RAM

This state offers significant power savings as everything in the system is put into a low-power state, except for memory, which is placed into the self-refresh mode to retain its contents.

NOTE:
The test in this section was performed with LCD display disconnected.

To suspend to RAM:

Enable Wi-Fi if not enabled to ensure the firmware is loaded:
$ ifconfig wlan0 up

Disable Wi-Fi to put it into sleep state:
$ ifconfig wlan0 down

Disable Bluetooth
$ echo 0 > /sys/class/gpio/gpio132/value

Enter Sleep mode
$ echo mem > /sys/power/state

Wake up

There are many possible ways to wake up from suspend.
A few examples:
- Pushing the ON/OFF button (when present on the board)
- Pushing a button on the board which has the boolean property "gpio-key,wakeup" set in its device tree node (under gpio_keys), e.g.:

	gpio-keys {
		compatible = "gpio-keys";
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_gpio_keys>;

		back {
			label = "Back";
			gpios = <&gpio5 20 GPIO_ACTIVE_LOW>;
			linux,code = <KEY_BACK>;
			gpio-key,wakeup;
		};
	};

- Using the RTC you can wake at a specific time

Current consumption when suspended

To measure the current remove resistor R4 and connect ampere meter instead.
The current consumption should be measured is around 5mA at 3.3V