Retention Standby Mode

Materials

• AMB82-mini x 1

• Optional: Push button x 1

• Optional: Register 220 ohms x 1

Example

In this example, the development board will demo the retention Standby Mode for power save. There are 4 wake-up retention sources. The system will count down 5s then go to Stand By mode. Upon the wake-up source being triggered, the system will be reboot and wake up again without losing the retention value.

The module and board power consumption report under Standby mode are listed in these two tables below.

RTL8735B module power consumption test results

Wake-up source	Module power consumption (uA)
	Stand By Mode (measure at 3V3)
AON timer	41.22
AON GPIO	41.28
PON GPIO	41.07
Gtimer0	41.48

AMB82-MINI board Power Consumption

Wake-up source	Development board power consumption Approximate measurement (mA)
	Normal Mode	Standby Mode
AON timer	53.15	4.79
AON GPIO	53.12	4.81
PON GPIO	55.09	4.87
Gtimer0	55.59	4.83

Open example in File -> Examples -> AmebaPowerMode -> RetentionStandbyMode

Next is setting up the system and entering the power mode. Please refer to the following steps for entering Standby mode.

Use the USE_MULTIPLE_WAKEUP_SOURCES configuration flag to set for multiple or single wakeup sources.

0: single

1: multiple

Multiple Wake-up Sources

You can use bitwise OR to setup multiple wakeup sources for MULTI_WAKEUP_SOURCE

SLP_AON_TIMER (BIT0) - AON Timer wakeup

SLP_AON_GPIO (BIT1) - AON GPIO wakeup

SLP_PON_GPIO (BIT4) - PON GPIO wakeup

SLP_GTIMER (BIT7) - GTimer wakeup

Note

SLP_RTC is not supported with retention SLP_GTIMER is automatically added when retention is enabled

For AON timer, please set CLOCK value to 0 or 1, 0:100kHz, 1:4MHz, SLEEP_DURATION unit is in seconds.

For AON GPIO, please set the AON_GPIO_PIN value to 21 or 22.

For PON GPIO, please set the PON_GPIO_PIN to value between 0 and 11. The GPIO pin is set to active high, please refer to the following connection.

For GTimer, please set the value for GTIMER_DURATION, the timer sleep duration in seconds.

To define retention variables, please refer to the following diagram.

Single Wake-up Sources

Step 1. Ensure RETENTION is “#define RETENTION 1” in this example.

Step 2. Set up the “WAKEUP_SOURCE”, AON timer: 0; AON GPIO: 1; PON GPIO: 2, Gtimer0: 3.

Step 3. Set up the wake-up source setting. There are 4 wake-up sources, each one has its own settings.

For AON timer, at section “#if (WAKEUP_SOURCE == 0)”, set value to “CLOCK” and “SLEEP_DURATION”. “CLOCK” can be 4MHz or 100kHz. “SLEEP_DURATION” unit is in seconds.

For AON GPIO, at section “#elif (WAKEUP_SOURCE == 1)”, set value to “WAKUPE_SETTING”. “WAKUPE_SETTING” in this case is the Pin number, that can be 21 or 22. The GPIO pin is set to active high, please refer to the following connection.

For PON GPIO, at section “#elif (WAKEUP_SOURCE == 2)”, set value to “WAKUPE_SETTING”. “WAKUPE_SETTING” in this case is the Pin number, that can be 0 to 11. The GPIO pin is set to active high, please refer to the following connection.

For Gtimer0, at section “#elif (WAKEUP_SOURCE == 3)”, set value to “SLEEP_DURATION”. “SLEEP_DURATION” is the timer sleep duration in seconds.

Step 4. Start the Deep Sleep mode. There is only 1 optional setting for this step.

Step 5. Define retention variables.

To wake up, all timers will automatically wake up when the duration is finished, all GPIO pins must active high by pressing the push button.

The correct boot, enter Standby, reboot cycle, and printed retention data will be same as following picture.