SPRUHZ7K August 2015 – April 2024 AM5706 , AM5708 , AM5716 , AM5718 , AM5718-HIREL
The RTC supports the power idle protocol. The RTC has two SWakeup ports: one for the alarm event and one for a timer event.
When the RTC is in IDLE mode, the clock is turned off and the 32 kHz clock remains on. The time and calendar continue to count in IDLE mode. When the RTC is placed back in FUNCTIONAL mode, the TC registers can be read. The RTC idle mode configuration is done through the RTC_SYSCONFIG_REG[1:0] IDLEMODE bit (see Table 23-7).
IDLEMODE | Description |
---|---|
0x0 | Force IDLE: idle state of the local target follows (acknowledges) the system IDLE request unconditionally |
0x1 | No-idle mode: RTC never enters idle state |
0x2 | Smart-idle mode: RTC subsystem waits for all interrupts/events to be serviced before entering in IDLE mode. |
0x3 | Smart-idle wakeup-capable mode: RTC eventually acknowledges the system IDLE requests, depending on its internal requirements, RTC can generate wakeup events when in idle state. |
The Alarm SWakeup event can be used to wake up the RTC when it is in idle state. To do so, the alarm must be set and enabled before RTC enters idle state. Also the wakeup generation for alarm/timer event must be set (bits [1:0] in the RTC_IRQWAKEEN register). Once this is done, the SWakeup event occurs when the alarm event triggers.
SWakeup is not periodic, using Timer SWakeup event to wake up the RTC when in idle state is not recommended. Use Alarm SWakeup instead.
There are two idle modes: smart-idle mode and smart-idle wakeup-capable mode. The RTC should be configured to smart-idle wakeup-capable mode in order to use the SWakeup events.