DART-6UL suspend

From Variscite Wiki
Suspend to RAM

1 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
# pm-suspend

2 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;
		};
	};

3 Current consumption when suspended

To measure the current remove resistor R4 on the 6ULCustomBoard and connect an ammeter instead.
The expected measured current consumption should be around 4.5mA at 3.3V