I found the code below. The person who post this code mentions that he used the ATmega328 chip which is the same chip that is used in Arduino Uno.
So I think this code is supposed to be used with Uno. However I uploaded it to my Leonado and it broke. It powers and is detected when the bootloader is running. But after 5 seconds it disconnects and windows displays a message saying that the USB device is not recognized. I presume as the code below seems to be setting some registers, something has messed up. I tried it again on another Leonardo, and the problem happened again!
I only have one Arduino Uno and really dont want to break it, even thought this code is meant to work on it.
How can I fix my Leonados? and if I upload this code to my Uno will the same problem occur?
http://www.fiz-ix.com/2012/11/low-power-arduino-using-the-watchdog-timer/#comment-1440
#include <avr/sleep.h>
// This library contains functions to set various low-power
// states for the ATmega328
// This variable is made volatile because it is changed inside
// an interrupt function
volatile int sleep_count = 0; // Keep track of how many sleep
// cycles have been completed.
const int interval = 5; // Interval in minutes between waking
// and doing tasks.
const int sleep_total = (interval*60)/8; // Approximate number
// of sleep cycles needed before the interval defined above
// elapses. Not that this does integer math.
void setup(void) {
watchdogOn(); // Turn on the watch dog timer.
// The following saves some extra power by disabling some
// peripherals I am not using.
// Disable the ADC by setting the ADEN bit (bit 7) to zero.
ADCSRA = ADCSRA & B01111111;
// Disable the analog comparator by setting the ACD bit
// (bit 7) to one.
ACSR = B10000000;
// Disable digital input buffers on all analog input pins
// by setting bits 0-5 to one.
DIDR0 = DIDR0 | B00111111;
}
void loop(void)
{
goToSleep(); // ATmega328 goes to sleep for about 8 seconds
// and continues to execute code when it wakes up
Serial.println("1");
if (sleep_count == sleep_total)
{
Serial.println("2");
// CODE TO BE EXECUTED PERIODICALLY
}
}
void goToSleep()
{
// The ATmega328 has five different sleep states.
// See the ATmega 328 datasheet for more information.
// 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
// I am using the deepest sleep mode from which a
// watchdog timer interrupt can wake the ATMega328
set_sleep_mode(SLEEP_MODE_PWR_DOWN); // Set sleep mode.
sleep_enable(); // Enable sleep mode.
sleep_mode(); // Enter sleep mode.
// After waking from watchdog interrupt the code continues
// to execute from this point.
sleep_disable(); // Disable sleep mode after waking.
}
void watchdogOn() {
// Clear the reset flag, the WDRF bit (bit 3) of MCUSR.
MCUSR = MCUSR & B11110111;
// Set the WDCE bit (bit 4) and the WDE bit (bit 3)
// of WDTCSR. The WDCE bit must be set in order to
// change WDE or the watchdog prescalers. Setting the
// WDCE bit will allow updtaes to the prescalers and
// WDE for 4 clock cycles then it will be reset by
// hardware.
WDTCSR = WDTCSR | B00011000;
// Set the watchdog timeout prescaler value to 1024 K
// which will yeild a time-out interval of about 8.0 s.
WDTCSR = B00100001;
// Enable the watchdog timer interupt.
WDTCSR = WDTCSR | B01000000;
MCUSR = MCUSR & B11110111;
}
ISR(WDT_vect)
{
sleep_count ++; // keep track of how many sleep cycles
// have been completed.
}
Thanks
Kiwi
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