first commit

ATMEGA_SLEEP_ADC/ATMEGA_SLEEP_ADC.ino

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+#include <avr/sleep.h>
+#include <avr/power.h>    // Power management
+#include <avr/wdt.h>
+
+const byte LED = 13;
+  
+// watchdog interrupt
+ISR (WDT_vect) 
+{
+   wdt_disable();  // disable watchdog
+}  // end of WDT_vect
+
+void myWatchdogEnable() 
+{
+  // clear various "reset" flags
+  MCUSR = 0;     
+  // allow changes, disable reset
+  WDTCSR = bit (WDCE) | bit (WDE);
+  // set interrupt mode and an interval 
+  WDTCSR = bit (WDIE) | bit (WDP3) | bit (WDP0);    // set WDIE, and 8 seconds delay
+  wdt_reset();  // pat the dog
+
+  byte old_ADCSRA = ADCSRA;
+  // disable ADC to save power
+  ADCSRA = 0;  
+
+  // slow clock to divide by 256
+ // clock_prescale_set (clock_div_256);
+
+  // ready to sleep
+  set_sleep_mode (SLEEP_MODE_PWR_DOWN);  
+  sleep_enable();
+
+  // turn off brown-out enable in software
+  MCUCR = bit (BODS) | bit (BODSE);
+  MCUCR = bit (BODS); 
+  sleep_cpu ();  
+
+  // cancel sleep as a precaution
+  sleep_disable();
+  power_all_enable ();   // enable modules again
+    // reenable ADC
+  ADCSRA = old_ADCSRA;  
+} 
+
+ 
+void setup () { 
+  Serial.begin(9600);
+}
+
+void loop () 
+{
+  
+  pinMode (LED, OUTPUT);
+  digitalWrite (LED, HIGH);
+  pinMode (LED, INPUT);
+  delay (100);
+  digitalWrite (LED, LOW);
+  delay(10);
+  // sleep for a total of n x 8 seconds
+  for (int i = 0; i < 8; i++) {
+    myWatchdogEnable (); 
+  }
+  
+}