29.4.4 Sleep Mode Operation

The behavior in sleep mode depends on the clock source and the Run In Standby bit in the Control A register (CTRLA.RUNSTDBY):
  • Internal clocking, CTRLA.RUNSTDBY = 1: GCLK_SERCOMx_CORE can be enabled in all sleep modes. Any interrupt can wake up the device (except Frame error (FERR) and Parity error (PERR) that are part of the ERROR interrupt).
  • External clocking, CTRLA.RUNSTDBY = 1: The Receive Start and the Receive Complete interrupts can wake up the device. Any interrupt can wake up the device (except Frame error (FERR) and Parity error (PERR) that are part of the ERROR interrupt).
  • Internal clocking, CTRLA.RUNSTDBY = 0: The internal clock will be disabled after any ongoing transfer is completed. The Receive Start and Receive Complete interrupt(s) can wake up the device.
  • External clocking, CTRLA.RUNSTDBY = 0: The external clock will be disconnected after any ongoing transfer is completed. All reception will be dropped.

When targeting the lowest STANDBY power consumption for a transmit-only application, the receiver must remain disabled, but the receiver data pinout (CTRLA.RXPO) must be set to match the transmit data pinout (CTRLA.TXPO).