Timer1 Operation During Sleep

Timer1 can only operate during Sleep when set up in Asynchronous Counter mode. In this mode, an external crystal or clock source can be used to increment the counter. To set up the timer to wake the device:

The device will wake-up on an overflow and execute the next instruction. If the GIE/GIEH bit of the INTCON register is set, the device will call the Interrupt Service Routine.

The secondary oscillator will continue to operate in Sleep regardless of the TxSYNC bit setting.