You could have a el cheapo dual 556 timer chip at each camera, with one 10mS delay, and one 100ms, both triggered from the previous chips falling edge of the 10ms timer -  one 50 cent chip, 4 capacitors, and 3 resistors.

You would just need a 3 core cable between each camera ( ground, 5v, and trigger )

Of course you could have an Arduino to tell it when to fire ( keeping with the forum )

shouldn't it be that the only one who can vote Karma, is the original poster posing the question ?  it will tell if he/she was helped?

Or is that how it works?

thanks a lot,  that all looks very good, though some of us might have to Google a couple of the heroes - Shannon to me is  a lovely river in Ireland where Irish Whiskey was invented, by the chef at the Foynes flying boat terminal - a hero indeed  - how does that suit you  Grumpy Mike ?    

Ita a bit confusing for us not used to forums....

and how can I get my forum life that flashes before my eyes when I log on ( scrolling down in ghostly silhouette ) to go slower so I can see it!

Thanks to all you guys that helped me getting my video/audio announcer going at last.

I have battled the last couple of weeks with getting queued numbers to play in the right order, it would drop some numbers, and sometimes announce one number while displaying the next.

Early on I had a prototype that didn't queue, and the SD card reader and WaveHC library was working fine, even though I can not understand half the instructions used.

I had another look at the sample sketch that I had copied to load and play from the SD card, and found
 

Code:

void playfile(char *name) {
  // see if the wave object is currently doing something
if (wave.isplaying) {// already playing something, so stop it!
 //  wave.stop(); // stop it

Duh,    I wish I had seen that a while ago !  Not exactly cryptic is it :-) 

With it commented out, everything is running wonderfully, it will faithfully display and announce up to 10 messages in the queue.

I love my Arduino again     Thanks guys

So far so good, you guys have done well

Go and get some sleep now 

if you connect the transistors base to the chip via a say 4k7 resistor, emmiter to ground, then you can connect the leds in series ( with one resistor ) to a higher ( 12v ) voltage as the transistor is a buffer. ( leds to +v and collector )

thanks Rob I will try that

I dont understand how the save feature works,   with other design type software I usually open the last version I was working on, then save it as a new name ( usually with the date ) and then carry on working. I know then that I can always go back to yesterdays work irrespective of autosave.
With Arduino I end up with folders with the new name pde file, which is blank, and the orig pde file ???
If I try to just save, it tells me some things are read only so I must pick a new name and so on..

I have done a search but can find no explanation of how it works, any pointers anyone?

Thanks, I have heard about direct port access, and had a quick look.
I am still a newbie and feeling my way round the normal arduino type simple stuff.

This project I am on is actually rather complicated for a beginner but a client  saw my prototype and is pushing me for a working model, so I have to get this going asap.

Once I have that out I can rewrite the software at my leisure, if I don't get sidetracked by another project.............

That idea ( dropping the interrupt ) didnt work, but I have tweaked the original and its now working, except it drops one message from the queue if there is more than 2 !

It will do for now while I get the pcb done as I am sure I can sort it out with the software.

At the moment I am using the ISR to receive and queue subsequent commands while the announcement is playing and showing.

Then when the audio track is finished, I want to check if there is anything in the queue,

The main loop has to refresh the video shift registers ( its a 1280 x 720 HD display I am syncing to ) and doesn't like too much extra work, or I lose sync...

But perhaps I will try looking for the vt input during the bottom half of the screen, where there is no video, and I have a spare 8 milliseconds to decode and queue it....

I have just tested the basic queue and dequeue functions in this little sketch and it works fine, so I don't know where my problem lies.....
unless I have to add some delay perhaps in the dequeue?

Code:

#include <FIFO.h>
int door;    
FIFO<int,10> fifo; //store 10 ints
/////////////////////////////////////////////////////////
void setup ()   {
  Serial.begin(9600);
  for( door= 9; door >5; door-- )
  {    
    fifo.enqueue(door);  
  }
}
///////////////////////////////////////////////////////
void loop ()
{
  if (fifo.count () > 0 )   //  sees if there are any unread numbers in queue subroutine
  {
    Serial.println ( "and now for the countdown" );
    door = fifo.dequeue();  //  returns first unread number in queue
    {
      Serial.println ( door );  // print current door number
      delay (200);
    }
  }
  if (fifo.count () == 0 ) {
    delay ( 5000 );  // waits 5 seconds and adds some more into queue
    door = 7;
    fifo.enqueue (door);
     door = 9;
    fifo.enqueue (door);
     door = 2;
    fifo.enqueue (door);
        
    }
  }

Thanks for everyones help last year, I have got my vga overlay thing sort of working, but still have some trouble with the queueing of the announcements/displays.

I have tried to simplify my pseudo program.

My setup is :-

 I have a Holtek HT12 encoder/ RF link /decoder to send a door number  from 1 to 9.

The VT ( valid transmission ) output from the decoder is my interrupt input that has a routine to decode the BCD data to decimal 1-9, and put that number in a queue.

This is done with the one "video" micro, that also handle the display with a SPI library.
There is a second "audio" micro that handles the announcements  using WaveHC.h library and a SD card.

Once the announcement starts, it runs to the end of the track, and I use the "isplaying" signal to display the door number on the screen for that time.

The code below works, ( I have taken out or greyed most of the video side which is working fine ) its just the queueing again that I have a problem with.

It will play the track, but keeps repeating it, wherever I put the vtoutPin LOW to reset it.

Any ideas??   ( obviously with all the bits chopped out the curley braces will be wrong )

Code:

/*
 VGA overlay generator
 */
#include <FIFO.h>
#include <SPI.h>

volatile int bcda ; // define bcd digital inputs from HT12
volatile int bcdb;
volatile int bcdc;
volatile int bcdd;
// the VT valid transmission from the HT12 connects to pin4 to interrupt on RISING

volatile int door;    // door number to show and announce

int talking;     // LOW while audio running

/*int vb;          // part of display routine
int q = B11100000;   //part of display routine
*/
int aPin = A3; //binary data in from Holtek chip, representing door numbers 1 to 9
int bPin = A2;
int cPin = A1;
int dPin = A0;
/*int timingPin = 4;  // part of display routine
int windowPin = 6;  // part of display routine
*/
int runningPin = 12; // input from audio board, low when audio playing

int aoutPin = 10; //     queued bcd codes to audio board
int boutPin = 8;
int coutPin = 7;
int doutPin = 9;
int vtoutPin = 3;   // vt trigger to audio board to start playing,  audio board will play selected track from a SD card,
        //and hold "running pin" LOW until track is finished.

FIFO<int,10> fifo; //store 10 ints

/////////////////////////////////////////////////////////
void setup ()   {

  pinMode (aoutPin, OUTPUT );
  pinMode (boutPin, OUTPUT );
  pinMode (coutPin, OUTPUT );
  pinMode (doutPin, OUTPUT );
  pinMode (vtoutPin, OUTPUT );
  pinMode (runningPin, INPUT );
  pinMode(aPin, INPUT);
  pinMode(bPin, INPUT);
  pinMode(cPin, INPUT);
  pinMode(dPin, INPUT);
 // pinMode(timingPin, INPUT);
  //pinMode(fsPin, INPUT);
  //pinMode(windowPin, OUTPUT );
  attachInterrupt(0, queue, RISING);   // interupt routine from vt input ht12 to load new number to queue

}
//////////////////////////////////////////////////

void loop ()
{
   int talking = digitalRead (runningPin ); // checks to see if audio is playing ( will be LOW if it is )
  if (talking == HIGH) {  
    
    if (fifo.count () > 0 )   //  sees if there are any unread numbers in queue subroutine
    {
      door = fifo.dequeue();  //  returns first unread number in queue

        if (door == 1){
        digitalWrite ( aoutPin, HIGH);   // Sends the door number in bcd to the audio micro -
           // I havnt got round to shortening this bit yet !
        digitalWrite ( boutPin, LOW);
        digitalWrite ( coutPin, LOW);
        digitalWrite ( doutPin, LOW);
      }  

     // and so on for doors 1 to 8

      if (door == 9){
        digitalWrite ( aoutPin, HIGH);
        digitalWrite ( boutPin, LOW);
        digitalWrite ( coutPin, LOW);
        digitalWrite ( doutPin, HIGH);
      }  

    }
   digitalWrite ( vtoutPin, HIGH);   //  to audio board to begin announcement
  }

  ///////////////////////////////////////////////////////////////////////////////////////////

  //  all this is display routine
   /*   case 16:  
        SPI.transfer(h);
        SPI.transfer(q);  
        break;
         }
      break;

    }
    */
  ///////////////////////////////////////////////////////////////////////////////////////////  
     digitalWrite ( vtoutPin, LOW);  // resets the trigger to the audio micro, which goes on announcing for several seconds
    
    


}

void queue ()  {
  bcda = digitalRead ( aPin );  // check the state of the HT12 data outputs
  bcdb = digitalRead ( bPin );
  bcdc = digitalRead ( cPin );
  bcdd = digitalRead ( dPin );

  if (bcda==1 && bcdb==0 && bcdc == 0 && bcdd == 0 )
  {    
    door = 1;    }
    
    // and so on for doors 1 - 9
  
  if (bcda==1 && bcdb==0 && bcdc == 0 && bcdd == 1 ) {
    door = 9;
  }
  fifo.enqueue(door);
}

It works just as above.  and it only takes up 1470 bytes so I can fit it in with the existing micro.  (  and I found out what I was doing wrong with arrays at last ! )

The only SPI output I am using is the data, I have put a 2k2 resistor from pin 11 to the amplifier input, with a .22 mFD cap to ground from the the amp input.

this is the waveform from pin 11  red,, and after smoothing to the amp, green
http://www.flickr.com/photos/johnandlyn/5253303071/sizes/z/in/photostream/


It gives a dirty brown note full of distortion and harmonics, like a horn.
Now I am going to try a siren, seeing as I have plenty of memory to play with....

Code:

int latchPin = 8;
int clockPin = 12;
int dataPin = 11;
long int timer;


void setup() {
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
digitalWrite(latchPin, LOW);


}

void loop() {

  int noise[] = {
    B10111001,
    B01010000,
    B10111110,
    B00011110,
    B00001100,
    B11011011,
    B01000111,
    B00101110,
    B00010111,
    B10000011,
    B10001000,
    B11110100,
    B11100110,
    B01000011,
    B11111000,
    B01110000,
    B01110011,
    B01011100,
    B00011101,
    B10011000,
    B11101010,
    B01000110,
    B00100111,
    B11000111,
    B10100001,
    B00011111,
    B11000001,  
    B11001100,      
    B01110110,          
    B00111000,  
    B11111010,  
    B00011000,  
    B00100111,  
    B10000100,  
    B01111011,    
    B00011111,  
    B00000111,    
    B00110011,    
    B11111001,    
    B10001100,    
    B01100110,    
    B11110000,    
    B01111100,        
    B10011110,        
    B00010011,    
    B10011100,        
    B01101100,        
    B00111100,        
    B11001111,        
    B00000111,    
    B11000110,      
    B00110010,        // theres some spare lines here for messing with the note
  
  };

  for (timer = 0; timer<800;timer ++) { // gives approx  4 second burst with just this loop playing and a 16MHz xtal.

    for (int j = 0; j < 25; j++) {   // vary the 25 to change the note

      shiftOut(dataPin, clockPin, MSBFIRST, noise[j]);  
    
    }
  }
       delay(1000);                       // a break between toots !
  digitalWrite(latchPin, HIGH);
}