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Topic: Triggering a camera (Read 587 times) previous topic - next topic

Solus

Hi all,

I recently picked up a USB pen camera with SD card storage to fiddle about with as a project focus to get me learning electronics; to start myself off I thought I'd try my hand at triggering the camera with my mobile using Bluetooth. I've managed to knock out a Bluetooth trigger on my phone over the last couple of days & it's working fine with sending data to my Arduino Mega using a BlueSMiRF however I'm having trouble overriding the switch to trigger the camera, I've had a probe & there's 3.5v going through the switch when bridged. Manual bridging with a bit of wire works fine & I've approximated the voltage being kicked out of pin 8 on the Mega using the code below:

Code: [Select]
analogWrite( 8, 182 );

I've checked the voltage with an ammeter & it's around 3.51v so I believe should simulate the bridging of the switch, however it doesn't appear to be working.

I'm a bit lost as to where to go from here, can I even use PWM in this manner or am I barking up the wrong tree? Any ideas would be much appreciated!


Many thanks in advance!

fkeel


the name of the function analogWrite() is poorly chosen... I think there are ways of using capacitors to smooth out the signal to do what you want it to ... others who know more about electronics might be able to help you with that. As is, you are not producing 3.5V, but rapidly switching between 5V and 0V which wont have the desired effect.

Have you considered simply using a transistor instead of the switch?

Solus

Damn, I thought that might be the case. I did have a look into capacitor smoothing, hadn't thought of using a transistor though; would a transistor not be subject to the same issue with the modulating voltage supplied by PWM?

Grumpy_Mike

This is how PWM works:-
http://www.thebox.myzen.co.uk/Tutorial/PWM.html

Quote
would a transistor not be subject to the same issue with the modulating voltage supplied by PWM?

It would but you don't feed PWM into the transistor, just a steady high or low through a resistor. When you feed the base high the transistor turns on and acts like your shorted wire. When you feed the base with a low signal the transistor turns off just like removing your wire.
Just as the wire has two ends so must your circuit. That means connecting the arduino ground to the ground of your camera.

Solus

Gotcha, I was stuck thinking about PWM in particular & forgot about my other options  :smiley-sweat: I'll have a fiddle about with a breadboard & see what I can get working!

Many thanks!

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