System Hibernation is a shutdown mode where all device functions are shut off.
The device enters System Hibernation mode through register SYSTEMHIBERNATE. While in System Hibernation mode, the device is in a low power state where the current consumption is minimal. After entering this mode, the device will only restart following a pin reset. For more details, see Reset behavior.
RAM is not retained in System Hibernation mode.
Before entering System Hibernation mode, all ongoing EasyDMA transactions must finish. See peripheral specific chapters for more information about EasyDMA transaction status.
During System Hibernation mode, GPIO pins retain their configured states (for example, output
pins remain output). When the device wakes up, it behaves as if being reset, but the GPIO pins
remain in a retained state and must be reconfigured and released by performing the following steps:
- Configure the GPIO pin registers using the GPIO peripheral PIN_CNF registers.
- Write Release to REGULATORS.HIBERNATOR.GPIORETENTIONRELEASE to activate the GPIO pin settings.
When entering System Hibernation mode, the debugger is disconnected. Ensure that the device
is in a state where the debugger can be connected before entering System Hibernation. If
System Hibernation mode is entered immediately after device start-up, a debugger cannot
connect to the device. To ensure a debugger is able to connect to a device using System
hibernation mode, follow these guidelines:
- After reset, ensure a 200 millisecond delay to allow the debugger sufficient time to establish a stable connection.
- Ensure the debugger is disconnected by using the debug power-up register DBGPWRUPREQ.
- Activate System Hibernation mode by writing to SYSTEMHIBERNATE.