Arduino Intervalometer Power Consumption

One of my first Arduino projects was an intervalometer used for taking time lapses. A very basic yet fully featured creation with an LCD and everything. However in planning for travelling this summer, this big RadioShack box full of wires and other conspicuous-looking stuff might not be very TSA friendly.

A new design I plan for is an atmega328 standing alone with a 16MHz oscillator. Alongside that are a small LED, 2N2222, and an 8 channel dip switch package. The 8-channel dip switch is for setting the intervals in seconds with binary.

My question is weather or not I would be able to power the atmega328 and notification led with a single 3 volt CR2032 coin cell battery, and weather or not I could power it for very long. Any idea?

You’d have to run at a slower speed, 8-10 MHz, see Figure 28-1 of the 328 datasheet.
and likely not for very long with a CR2032.
They’re only good for 240mAH total,

So even if you could get 30mA out of it, it’s be dead in 8 hours.
Any chance you could use 3 AAAs or 3 AAs instead? has very nice 3 AAA battery boxes with switch, or a single battery with boos regulator if you want it even smaller.
You can get 8 MHz xtal, socket, two 22pf caps, 10K resister, 8 position dip switch from dip micro all for <$2 or so, $2 shipping.

Even better
with 8 Mhz crystal, 22 pf caps, dip switch and have some parts for next project.

Ah, I see CrossRoads,

I suppose I could go with a AA battery design. I was originally planning for all this to be held in a small Altoids gum container, but now a regular Altiods tin seems fine. However in concern for space, could I power the 328 for a considerable time directly from 2 AA batteries instead of 3?

Perhaps look into making the chip sleep for a bit - I'm not sure of the specifics, but having it sleep of some sort for the majority of a second and wake up for the tiny bit of time it is needed could save you a bit of battery power.

Sure, you can do 2 AAs with a boost regulator like this

Sleep mode would help also - perhaps sleep after the interval is up, one button push to wake up & read new time to use from the switches (and to assure you you still have battery life with a couple of LED blinks or something) & 2nd push to start the timer

Thanks guys, I think 3AAs will do me good.

However in troubleshooting my code, I realised that the Arduino does not want to delay any value over 32000 milliseconds. Any quick ideas, or should I start a new thread elsewhere?

Check out the code:

// Binary Intervalometer
// By Physics_Dude
// Digi-pins 2 - 9 have dip switches
// Digi-pins 11 - 13 are for LED, focus, and shutter

// Set dip pins
const int buttonPin2 = 2;     
const int buttonPin3 = 3; 
const int buttonPin4 = 4;    
const int buttonPin5 = 5;
const int buttonPin6 = 6;    
const int buttonPin7 = 7;  
const int buttonPin8 = 8; 
const int buttonPin9 = 9;  

// Set led, focus, and shutter pins
const int ledPin =  13;  
const int focusPin =  12;  
const int shutterPin =  11;  

int buttonState2 = 0;      
int buttonState3 = 0;      
int buttonState4 = 0;       
int buttonState5 = 0;       
int buttonState6 = 0;   
int buttonState7 = 0;         
int buttonState8 = 0;       
int buttonState9 = 0;    

// Delays
int DelayVal = 0;  //Delay value at startup
int hold = 100;  // Time shutter held down for

void setup() {
  // Inputs
  pinMode(buttonPin2, INPUT);
  pinMode(buttonPin3, INPUT);
  pinMode(buttonPin4, INPUT);
  pinMode(buttonPin5, INPUT);
  pinMode(buttonPin6, INPUT);
  pinMode(buttonPin7, INPUT);
  pinMode(buttonPin8, INPUT);
  pinMode(buttonPin9, INPUT);        

  // Outputs
  pinMode(ledPin, OUTPUT);      
  pinMode(focusPin, OUTPUT);      
  pinMode(shutterPin, OUTPUT);      

void loop(){
  // Turn all outputs off
  digitalWrite(ledPin, LOW);   // LED off
  digitalWrite(focusPin, LOW);   // Focus not pressed
  digitalWrite(shutterPin, LOW);   // Shutter not pressed
  // Read the states of the dip values:
  buttonState2 = digitalRead(buttonPin2);
  buttonState3 = digitalRead(buttonPin3);
  buttonState4 = digitalRead(buttonPin4);
  buttonState5 = digitalRead(buttonPin5);
  buttonState6 = digitalRead(buttonPin6);
  buttonState7 = digitalRead(buttonPin7);
  buttonState8 = digitalRead(buttonPin8);
  buttonState9 = digitalRead(buttonPin9);

  // Lazy math time!  
  // Bit 1
  if (buttonState2 == HIGH) {     
    DelayVal = DelayVal + 1;  

  // Bit 2
  if (buttonState3 == HIGH) {     
    DelayVal = DelayVal + 2;  

  // Bit 3
  if (buttonState4 == HIGH) {     
    DelayVal = DelayVal + 4;  

  // Bit 4
  if (buttonState5 == HIGH) {     
    DelayVal = DelayVal + 8;  

  // Bit 5
  if (buttonState6 == HIGH) {     
    DelayVal = DelayVal + 16;  

  // Bit 6
  if (buttonState7 == HIGH) {     
    DelayVal = DelayVal + 32;  

  // Bit 7
  if (buttonState8 == HIGH) {     
    DelayVal = DelayVal + 64;  

  // Bit 8
  if (buttonState9 == HIGH) {     
    DelayVal = DelayVal + 128;  
  // Full byte complete! 

  // Convert to milliseconds
  DelayVal = DelayVal * 1000;

  // Compensate for shutter press delay.
  DelayVal = DelayVal - hold;

  //Minimum Delay is 1 second
  if (DelayVal < 1000)
    DelayVal = 1000;

  // Delay for "DelayVal" milliseconds

  // Done? Now activate outputs!
  digitalWrite(ledPin, HIGH);   // LED on
  digitalWrite(focusPin, HIGH);   // Focus pressed
  digitalWrite(shutterPin, HIGH);   // Shutter pressed
  delay(hold);   // Time shutter is held down 

  // Reset DelayVal
  DelayVal = 0;


Delay is already in mS

" // Convert to milliseconds DelayVal = DelayVal * 1000;" So this is convert to seconds

0xFF = 255, * 100 = 255000, which is more than 16 bits (65,535 tops) that an int can hold

Your comments say the min delay is 1 second, 1000mS = 0x03e8

Why not make a blink without delay void loop instead? unsigned long duration = 1000* (128*switch + 64*switch7 +32*switch5+16*switch4+8*switch3+4*swithch2+switch1) Note the time that your timer started unsigned long start_time =millis(), , then go thru void loop comparing how much time has gone by unsigned long elapsed = millis() - start_time if elapsed >= duration {stop the timer}

Thanks again, I forgot the existence of long variables, It works now.

And the "Lazy math time!" comment was there for a reason, warning of a copy/paste routine that followed. :grin:

I like the green smile!

Try it blink without delay style too, see how that goes. Then you can add other things in - flash the LED every 1/2 or 1 second as it counts down ...