PIR Servo Control?

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi

As I am a complete arduino novice...I need some Help!

I am trying to use a PIR (Essence Security Ltd) sensor to trigger a 180 degree turn of a servo, followed by a 3 minute gap and then the servo turning back 180 degrees to its original position.

I am using it to turn on a film projector, wait for the film to finish and then turn the projector off.

Does anyone know any suitable code for this? or how I can combine the servo code I have written with code for a PIR motion sensor

Thanks

Andy

2

The Essence website doesn't have much on the PIR.
Do you know how the trigger condition is indicated?
Relay closure?

loop ()
{
if (PIR_TRIGGERED ())
{
myServo.write (180);
for (seconds=0; seconds < 180; ++ seconds) {
delay (1000);
}
myServo.write (0);
// May be a delay here to avoid immediate retriggering
// and damage to the projector bulb
}
}

3

thanks AWOL!

I have realised that I could do the same thing with a push button or a switch, which is also more in context with the installation I am building.

Could I apply the code you have written to a push button? I am aware that buttons and switches work in terms of HIGH and LOW, but Servos work in 0-180 degrees so how do I deal with this?

Sorry if this is all very obvious! I have tried these instructions:

https://sites.google.com/a/divinechildhighschool.org/electronics/Home/Arduino-Lessons/servo-how-to

They kind of work when I change a few values, but the servo seems to constantly jitter and occasionally rotate even when the button is not pushed.

thanks for the help

4

If you look, I've written the example with a simple "PIR_TRIGGERED ()".
This could be anything - a simple macro, or a function that could read either a hardware pin, serial message, and I2C device, or just a simple table or flag.
The function simply has to return a one or a zero (strictly speaking, all it has to return is zero or non-zero).
If it returns a non-zero value, then the code following the "if" will be executed, so the servo turns to 180, there's a pause of 180 seconds, then the servo returns to zero.
If the function returns zero, then "loop" simply gets executed again, so the function/macro "PIR_TRIGGERED" gets called again.

5

Sorry, missed the bit about jitter.
This could be a power-supply issue (are you just using the USB to power the whole thing?), or possibly an earth (ground/gnd) problem.
Or an old servo with a dirty pot.