Re: PIC24FJ128GA204, Can Timer 4 be setup to wake from sleep using the LPRC clock?
☼ Best Answerby awolfe 2018/02/12 09:53:23
You can indeed wake up the CPU in SLEEP mode because LPRC is a separate oscillator (see figure 9-1 of the datasheet).
However, the trick is that the timer you want to use MUST be asynchronous, i.e. not synchronized by the internal clock as it is stopped.
If you look carefully at the figure 13-1, you will notice a small bloc called SYNC between PRESCALER and TMR2 (TMR4). Due to this SYNC box, TMR2 and TMR4 cannot wake up this device in SLEEP mode.
you will need to use either TMR1 / TMR3 or TMR5 which are asynchronous (they don't have this SYNC unit) figure 12-1 and 13-3.