SLEEP & ULPWU Help

[Armondo522]

Hi,

I am using a PIC 16F886 Micro with a ULPWU feature. I am feeding a voltage level to the ULPWU Pin from a sensitive light sensor. I want to put the micro to sleep while there is light available and wake up when it goes dark for a given interval. Below is my code. It appears to be working in just the opposite manner than I anticipated. When I cover the sensor, I get no reaction. When I slowly move my hand away from the sensor and let light shine on it. The routine wakes up and times out normally.
Should I put all the control code shown in main in the ULPWU ISR? Or am I just going about this the wrong way.
Any Help appreciated.

Thanks

void main()
{
set_tris_A(0b11111111);

setup_oscillator(OSC_4MHZ);
setup_adc_ports(sAN1|VSS_VDD);
setup_adc(ADC_CLOCK_INTERNAL);
setup_spi(SPI_SS_DISABLED);
set_adc_channel (1);

clear_interrupt(int_ULPWU);

enable_interrupts(INT_ULPWU);
enable_interrupts(INT_EXT); // pyro interrupt
EXT_INT_EDGE(L_TO_H);

read_switch(); // get timeout value

PIE2=0B00000100; // setup ULPWU Interrupt
PCON=0B00100000; // in case compiler does'nt
enable_interrupts(GLOBAL);

output_low(pin_C1); /// led ground
output_High(pin_A7);// pyro test


do //start of loop
{
restart: // jump after wakeup

if(lite_leds) // start of sequence depend on flag
{
clear_interrupt(int_ULPWU); // int must have fired to get here
disable_interrupts(INT_ULPWU); // disable for duration of test
sec_run=0;
setup_timer_2(T2_DIV_BY_16,187,16); // start and zero 1 sec timer
set_timer2(0);

enable_interrupts(INT_TIMER2); // 1 hz led flash routine

seconds_to_run= minutes_to_run*60; // calulate time to stay active
multiple= seconds_to_run/3;
first_timer= multiple;
second_timer=multiple*2;//
third_timer=multiple*3;

full_power(); // turn on leds full power

do
{
delay_ms(5);
if(get_voltage()>.5) // only on when its dark, reads sensor
// Get_Voltage A/D routine
{
goto all_over; // exit and shutdown if light is back on
}
}while(sec_run<first_timer); // 1st time interval
output_low(pin_B2);
delay_ms(10); // reset driver

two_thirds_power(); // 2/3 power

do
{
if(get_voltage()>.5) // only on when its dark
{
goto all_over;
}
delay_ms(5);
}while(sec_run<second_timer);

output_low(pin_B2);
delay_ms(10);

one_third_power(); // 1/3 power

do
{
delay_ms(5);
if(get_voltage()>.5) // only turn on when its dark
{
goto all_over;
}
}while(sec_run<third_timer);

all_over:

lite_leds=false; // clear flag end of sequence

output_low(pin_B2); // turn off leds
output_low(pin_C0); // turn off 1 hz led
clear_interrupt(int_ULPWU);
disable_interrupts(INT_TIMER2);
enable_interrupts(INT_ULPWU); // so we can start again
} // end of IF

sleep(); // goto sleep if there is light

#ASM // stop here after sleep
NOP
#ENDASM

if(get_voltage()>.5) // in case of a false trip on sensor
{ // recycle and wait
goto all_over;
}

lite_leds=true;

}while(true); // end of loop MAIN

}

[Ttelmah]

Learn to use the code buttons.....

Get rid of your direct setups for ULPWU.
Disable the INT_GLOBAL (otherwise the EXT interrupt will also wake you).
Have just a 'delay_cycles(1)' as the first instruction after the sleep (this codes a NOP).
Then use the sleep_ulpwu function. This allows you to specify the charge time (in uSec), and then wakes when the capacitor discharges and triggers the ulpwu.

However the purpose/reasoning behind your code is not clear. You have a line saying that ULPWU must have triggered to get here, yet if ULPWU has triggered or INT_EXT has triggered, it won't reach this line, since you have no interrupt handlers at all shown.

With interrupts, you have two choices:
Have them enabled, and INT_GLOBAL _disabled_. You can then poll the interrupts, or wake from sleep with them.
If INT_GLOBAL is enabled as well, you _must_ have handler code.

Best Wishes

[Armondo522]

Thank you for the reply.
I do not want a timed interrupt, instead I need a level interrupt on the ULPWU pin. When light is on the sensor its above ViL. I want to interrupt when <ViL. The external interupt, should also have the same effect. I think my biggest problem is understanding what happens exactly happens after a wake up event occurs.

Thanks in advance.

[Ttelmah]

You can still just use the sleep_ulpwu function. Just set the charge time to 0.

However the problems with your code as shown still apply regarding interrupts.
You must never enable_interrupts(GLOBAL), without having interrupt handler code present. Even if you think the interrupts won't trigger, you must assume they will.

With interrupts, there is an individual 'enable', for each function, and the global enable. If both a set, whether or not you are asleep, the handler is needed, and will be called (when asleep, it'll happen one instruction after you wake). You must get rid of the enable_interrupts(GLOBAL) line, or add a handler for the interrupts.

When you 'sleep' (either ulpwu, or a normal sleep), if an enabled interrupt occurs _whether or not the INT_GLOBAL is enabled_, the chip will wake up. It'll execute the next instruction (which was prefetched when you went to sleep), and if the global interrupt flag is set, will then immediately call the handler code - problem since you don't have any. When the handler returns (or immediately if the global interrupt is disabled), the following code then executes.

Best Wishes

[Guest]

I have moved the whole routine to a function to be called after the micro wakes up. In the function I need to enable interrupts so I can count ticks for time. I think I understand how the sleep works now..

thanks a bunch