circuit and code for garage door opener with boe?
I want to use an old photoelectric garage door opener as a sensor for my stamp (that will eventually trigger video in jitter, but for now i'll be happy if it'll blink an led). i'm not sure how to wire it into the board of education without short circuiting. i'm also a little lost on the code - after assigning the inputs and outputs.
any advice?
any advice?
Comments
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Chris Savage
Parallax Tech Support
csavage@parallax.com
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Chris Savage
Parallax Tech Support
csavage@parallax.com
When the beam is unbroken - there's a .2V coming off the signal wire. when its broken, it reads 6.7 V.
So ... I was thinking - the two grounds in Vss. The signal wire in board with a resistor (?what strength?) to put it down to 5V at least. Then tap that into an input like P7. ?
Then code - it would be HIGH 7 to turn the LED on, LOW 7 to turn it off.
Does that sound close?
However, those protection diodes need something on the input to reduce the current they see when they try to protect the pin. For RS-232, (a -12 to +12 volt signal), a 22 Kohm resistor works well. Note the current being reduced is the 'clipped' current -- between 0 and 5 volts the resistor does very little. It's above and below that where the resistor has it's current-limiting effect.
So, putting a 22 Kohm resistor in series should provide sufficient protection for your 6.7 volt signal. Note you also don't want to 'load down' your 6.7 volt signal either -- and 22 Kohm should be sufficient for that, also.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Now --- I need to get the output that is currently lighting the led into my computer to a jitter program. Can I use the USB in that I have for programming as an out? How would I program that? OR - do I use midi? How do I wire in a midi connection?
Thanks!