somebody post a definitive answer to ULPWU.Please

[armondo58]

I have tried numerous solutions to ULPWU interrupts. They all seem to work at times. But often they do not work when other interrupts are active after the call. Can someone please give example that will work all the time. The sleep_ulpwu() from compiler does not seem to work. I am using v1024 chip is pic 16f886.

[PCM programmer]

[Ttelmah]

Any interrupt that is itself enabled - so:
enable_interrupts(INT_RB);
_will_ wake the system from sleep if the interrupt flag gets set, _or_ will prevent the system sleeping, if the interrupt flag is set before you call the sleep instruction.

Basically, before sleeping, you need to turn off _all_ interrupts except the ones that you want to wake the chip. Also, unless you want the wake up interrupt(s) to call a handler, disable_interrupts(GLOBAL);
You also need to clear the interrupts you are going to use, if they may have become set while the chip was awake. All this before sleeping.

Now, after waking, if you don't want handlers to be called for the interrupt(s) that woke you, you need to clear the interrupts, and/or disable them.
Remember that to _clear_ an interrupt (in the case of one triggered by a hardware event), you may also need to clear the hardware event itself - so in the case of INT_RB above, you would need to read PORTB, before clearing the interrupt.

Remember also, that in some cases, failure to handle an interrupt, can leave the hardware in a locked condition. So (for instance), if you left the master clock running, and disabled INT_RDA, while you slept, then woke up, cleared the interrupt, and re-enabled it, you have a very good chance, that the UART will now be in a locked condition. Problem here is that if two characters have arrived, and not been handled, the UART will have overflowed. So here you would have to either use: