PaulS:
Exactly how depends on a number of factors. Generating a RISING, FALLING, or LOW interrupt all can be done, depending on how the switch is wired. Which type(s) of interrupt wake the Arduino is the question.
Thanks for your help. There is no clock associated with the project, but all i wanted my arduino to do is to go to sleep (idle) when not in use, and i want to use FSR sensor to interrupt by waking up the arduino while pressing the FSR sensor, and as soon as FSR sensor is release, it will go back to sleep(idle) and move a motor to clockwise. Below is a code i have been working on for the past two days, please could you take a look at it and see if i m missing anything. thanks
#include <avr/interrupt.h>
#include <avr/power.h>
#include <avr/sleep.h>
#include <avr/io.h>
//
void setup(void)
{
DDRD &= B00000011; // set Arduino pins 2 to 7 as inputs, leaves 0 & 1 (RX & TX) as is
DDRB = B00000000; // set pins 8 to 13 as inputs
PORTD |= B11111100; // enable pullups on pins 2 to 7
PORTB |= B11111111; // enable pullups on pins 8 to 13
pinMode(13,OUTPUT); // set pin 13 as an output so we can use LED to monitor
digitalWrite(13,HIGH); // turn pin 13 LED on
}
//
void loop(void)
{
// Stay awake for 1 second, then sleep.
// LED turns off when sleeping, then back on upon wake.
delay(100);
sleepNow();
}
//
void sleepNow(void)
{
/* Now is the time to set the sleep mode. In the Atmega8 datasheet
* http://www.atmel.com/dyn/resources/prod ... oc2486.pdf on page 35
* there is a list of sleep modes which explains which clocks and
* wake up sources are available in which sleep modus.
*
* In the avr/sleep.h file, the call names of these sleep modus are to be found:
*
* The 5 different modes are:
* SLEEP_MODE_IDLE -the least power savings
* SLEEP_MODE_ADC
* SLEEP_MODE_PWR_SAVE
* SLEEP_MODE_STANDBY
* SLEEP_MODE_PWR_DOWN -the most power savings
*
* the power reduction management <avr/power.h> is described in
* http://www.nongnu.org/avr-libc/user-man ... power.html
*/
// Set pin 2 as interrupt and attach handler:
attachInterrupt(0, pinInterrupt, LOW);
delay(100);
//
// Choose our preferred sleep mode:
set_sleep_mode(SLEEP_MODE_IDLE);
//
// Set sleep enable (SE) bit:
sleep_enable();
power_adc_disable();
power_spi_disable();
power_timer0_disable();
power_timer1_disable();
power_timer2_disable();
power_twi_disable();
//
// Put the device to sleep:
digitalWrite(13,LOW); // turn LED off to indicate sleep
sleep_mode();
//
// Upon waking up, sketch continues from this point.
sleep_disable();
digitalWrite(13,HIGH); // turn LED on to indicate awake
}
//
void pinInterrupt(void)
{
detachInterrupt(0);
}