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Power Off and Wake Up using GPIO Key Button

This section describes how to set up GPIO key button for power off and wake up purpose.

The brief set-up flow is as following.

Connect a tab button to the pin port you want to use
Set GPIO number using boot.ini
Compiling and flash the modified kernel dts : This part is only needed on ANDROID.

1. Hardware Set-Up

First, You need to prepare a tab switch that are connected to two lines.
Red line is for Power Button and another Gray line is for the active level line (Ground or 3.3V Power).

For example, we will use Pin#29 of 40pin expansion connector.

The pin is assigned to GPIOX.BIT0 and its GPIO number is #228.
Connect the red line to Pin#29.

Its default pin pulled status is high and switch active will be Low, so you should connect the gray line of tab switch to Ground (GND), Pin#30.

Pin Number (Red Line)	GPIO Number	Active Level (Gray Line)
29	GPIO#228	Active Low (Pin 30)

Setting boot.ini

You can assign GPIO number with env gpiopower in boot.ini.

# gpio power key : J2 (2x20) Pin#29 , GPIOX.BIT0
setenv gpiopower "228"
...
...
setenv bootargs ${bootargs} gpiopower=${gpiopower}

Setting Power Button Action for Power Off

Ubuntu

When you turn the board off using power button, you need to change power key action pattern.

- Open Power Management Preferences : [System] → [Preferences] → [Hardware] → [Power Management]
- and then Select [General] tab

Android

In case of Android, one short power key event is used for sleep and with long key event, you can handle options of power off/reboot.
With Android Marshmallow v2.4 or higher version, it's available to enter power off sequence using long-pressing (5 sec).

Available Key Numbers

1. J2 - 2×20 pins

Pin Number	Net Name	GPIO Number	Active Level	Pin Number	Net Name	GPIO Number	Active Level
1	3.3V Power			2	5.0V Power
3	I2CA_SDA	N/A		4	5.0V Power
5	I2CA_SCL	N/A		6	Ground
7	GPIOX.BIT21	GPIO#249	High → Low	8	TXD1	N/A
9	Ground			10	RXD1	N/A
11	GPIOX.BIT19	GPIO#247	High → Low	12	GPIOX.BIT10	GPIO#238	High → Low
13	GPIOX.BIT11	GPIO#239	High → Low	14	Ground
15	GPIOX.BIT9	GPIO#237	High → Low	16	GPIOX.BIT8	GPIO#236	High → Low
17	3.3V Power			18	GPIOX.BIT5	GPIO#233	High → Low
19	GPIOX.BIT7	GPIO#235	High → Low	20	Ground
21	GPIOX.BIT4	GPIO#232	High → Low	22	GPIOX.BIT3	GPIO#231	High → Low
23	GPIOX.BIT2	GPIO#230	High → Low	24	GPIOX.BIT1	GPIO#229	High → Low
25	Ground			26	GPIOY.BIT14	GPIO#225	Low → High
27	I2CB_SDA	N/A		28	I2CB_SCL	N/A
29	GPIOX.BIT0	GPIO#228	High → Low	30	Ground
31	GPIOY.BIT8	GPIO#219	High → Low	32	GPIOY.BIT13	GPIO#224	High → Low
33	GPIOX.BIT6	GPIO#234	Low → High	34	Ground
35	GPIOY.BIT3	GPIO#214	High → Low	36	GPIOY.BIT7	GPIO#218	High → Low
37	ADC.AIN1	N/A		38	1.8V Power	N/A
39	Ground			40	ADC.AIN0	N/A

2. J7 - 1×7 pins

Pin Number	Net Name	GPIO Number	Active Level
1	Ground
2	GPIOAO.BIT6	GPIO#128	High → Low
3	P5V0	5.0V Power
4	GPIOAO.BIT8	GPIO#130	High → Low
5	GPIOAO.BIT10	GPIO#132	High → Low
6	GPIOAO.BIT9	GPIO#131	High → Low
7	GPIOAO.BIT11	GPIO#133	High → Low

3. SW1

Pin Number	Net Name	GPIO Number	Active Level
1	NC	N/A
2	GPIOY.BIT5	GPIO#216	High → Low
3	GND	Ground

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