From Midday till Dusk

Light readings taken with the stormTrigger circuit from mid-day until dusk in Songkhla - Thailand.

The graph shows interval (x-axis) and A/D output (y-axis). Readings were taken at 400mS intervals.

Next step is to correlate the readings with actual light level measurements.

stormTrigger and 7D

Some video showing tests with 7D. Light was provided by a Canon 430EXII flash.

soundTrigger first shots

With soundTrigger set to activate the camera at 50 A/D counts above ambient, I got some shots of my lighter striking. They came out not too bad.

From breadboard to protoshield

Tests on both the light and sound circuits on breadboard were promising. They tests did show a great deal of false triggering and I believe this was due to the bad connection nature of breadboards.

I took both circuits and layed them out on protoboard. This allows direct connection to the Arduino.

Tests so far are very promising.

soundTrigger circuit with microphone in the background

stormTrigger V3 layed out and working well

soundTrigger rising

Playing with an electret microphone and a simple circuit.
A Mega328 samples the noise generated by the circuit and triggers a camera on the output via an opto-isolator.

Schematic in Eagle

Bread boarded Prototype

Measuring I/O performance

Performance looks promising. Measuring a triggering delay of 35uS (microseconds).
Arduino sketch to follow...

New light detector circuit

Prototyping the new light circuit on breadboard. Everything is working well so far.

Circuit detail (Transistor is wrong type but the correct footprint for the PCB)

Output in dim light is about 0.13V going up to just over 1V with an inspection lamp close to the transistor.

Photo Transistor

Low Power Op-Amp

This circuit will form the second PCB in a two stack design. Interconnects will be via pin headers (0.1") and power will be from a CR2032 3V coin cell battery.

The prototype PCB will be mostly SMD tech with the photo transistor and pin headers being through-hole.

Bit of code that just works...

/*
StormTrigger V3 30-07-2013
 */
#define FASTADC 1
// defines for setting and clearing register bits
#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif

#define LIGHT 0
#define OUT_FOCUS 2
#define OUT_SHUTTER 3
#define LED 13
int trigVal = 0;

void setup() {

#if FASTADC
  // set prescale to 16
  sbi(ADCSRA,ADPS2) ;
  cbi(ADCSRA,ADPS1) ;
  sbi(ADCSRA,ADPS0) ;
#endif
  pinMode(OUT_FOCUS, OUTPUT);
  pinMode(OUT_SHUTTER, OUTPUT);
  pinMode(LED, OUTPUT);
  PORTD = B01010000;
  // calibrate sensor to just above ambient reading
  int ambVal = analogRead(LIGHT);
  trigVal = ambVal + 40;
}
void loop() {
  //read light level
  int lightVal = analogRead(LIGHT);
  //compare light reading to trigger value
  if (lightVal >= trigVal)
  {
    //trigger camera
    PORTD = B00101100;
    delay(15);
    PORTD = B01010000;
    digitalWrite(LED, HIGH);
    delay(30);
    digitalWrite(LED, LOW);
  }

}

Version 3 - New Design

Hotshoe mounted
Built-in sensor
Coincell battery operation
Single LED feedback
Automatic setting & operation

35mm x 25mm x 15mm volume to work within.

Shown is the enclosure mounted on 7D.

Stacked PCBs. One uC PCB and one I/O PCB with a board interconnect.

Version 2 arrives...

The V2 PCB arrived from Silver Circuits last week. I am quite satisfied with performance after preliminary tests using Canon 5D MK3, 7D and Nikon D3100.

This circuit is a much more efficient board layout and dimensions come in at 8cm x 6cm. The LCD is an 8x2 type which is sufficient for display and settings.

Version 2 PCB with V0.96a software

This photo was taken using a DSLR with a radio trigger. Settings were 1/200 @ f2.8 with the flash set to 1/64th power, bounced at the ceiling. You can see the green LED within the rotary encoder is illuminated showing a flash has been detected.

I have added a second 3.5mm input to the PCB (center jack socket on the left) for expansion purposes I will go into later.

Contact me if you have any questions: phase1consult@gmail.com

Input & Output

Still in September 2011...

Input specifications:

The A/D input range of the Arduino Uno (Atmega328P) A/D is 0-5V with a range of 0-1023 representing fully dark (0) to fully bright (1023).

Light measurement to allow for ambient light from fully dark up to full sunlight, plus sufficient sensitivity to detect lightning pulses.

Types of light sensor played with were LDR (Light Dependent Resistor) and Photo Transistor. 

Output specifications:

While triggering a camera (Canon DSLR to be specific) I do not want any circuit voltages or power of any kind to be passed to the camera external trigger port. In order to prevent this an optically isolated Solid State Relay was reviewed. Two devices were looked at (ASSR1219 and ASSR1228) as they are dual channel devices with low power requirements and with the control current set properly, they are very fast acting.

Circuit testing to be done.

Full information of the awesome Arduno microcontrollers can be found by following the link below:

http://arduino.cc/en/

The stormTrigger

Back to September 2011.

A quality camera triggering device is expensive.

The need for a lightning trigger was highlighted to me while staying in Hat Yai for a few days. Setting up a tripod on a balcony then setting the camera to long exposure mode, and continuously pressing the shutter, hoping to capture a lightning strike proved to be very hit & miss.

I have been playing with Atmega microcontrollers for a few months now, developing my understanding of programming and interfacing with sensors.

I set about deciding upon the specifications.