Hello,
I am in need for some advice.... I am trying to connect two arduino boards to the same 24dc slave clock coil......each arduino board has a different program that reverses polarity one is set every 60 sec the other is every 2 sec how do I protect the Coil, L293DNE H-bridge and the Arduino board from someone flipping both switches at the same time

 

this is my diagram I have connected the coil to 2 switches and have 2+ and 2- going to the coil itself and I am using 24vdc not 9

 

Don't run the motor from the Arduinos 5V regulated output. 24VDC on the Arduino's 5V regulator will make it very hot even without the motor. Once the motor starts it'll probably shutdown the regulator.

 

ok thanks for the advice but I still have the same issue how would I protect the circuit from burning up if both arduino boards are turned on at the same time

 

Why not rethink your design using one Arduino or something more suitable to the job. Post a complete design schematic.

Why did you start a new thread on the same subject as your previous post? I see no reason a single Arduino couldn't do the job of your dual Arduino version.

 

Why not rethink your design using one Arduino or something more suitable to the job. Post a complete design schematic.

Why did you start a new thread on the same subject as your previous post? I see no reason a single Arduino couldn't do the job of your dual Arduino version.

I agree completely. Don't always go with your first design, sometimes you have to step back and ask, does this still make sense? Is there an easier way to do this?

Proper programming of the Arduino will be easier than a two boards.

 

OK this is what I have at this point does this make sense to anyone



http://forum.allaboutcircuits.com/attachment.php?attachmentid=58141&stc=1&d=13758048311

 

my question is how would the adruino know to change functions after the switches have been cycled switch 4 controls normal clock time and switch 5 is a setting mode that makes the hands move fast around the clock

 

Hello,
I am in need for some advice.... I am trying to connect two arduino boards to the same 24dc slave clock coil......each arduino board has a different program that reverses polarity one is set every 60 sec the other is every 2 sec how do I protect the Coil, L293DNE H-bridge and the Arduino board from someone flipping both switches at the same time

XOR gate comes to mind.

Your description seems very confused, but if you want an output from either signal, but no output when both signals coincide or neither signal is present then that is an XOR gate. This is probably not exactly what you want, and this question is the confusing part of your request. What should happen when you have both signals at the same time? Killing the output is probably not what you want. I suspect you want one signal to get priority.

Having offered that as a direct answer to your question, you really do need to do this in software, and using only one Arduino will keep the hardware and software more efficient.

 

Break down what you want into let's say 2 second intervals. Timer interrupts would come in handy for that, read switches (or better yet their interrupt flags) then some counters, etc...

Try finding an online flowchart diagrammer and plot out how it works, this can help everyone including yourself visualize your design.

To become a good programmer you have to be able to describe your problem precisely, us humans can try to guess what you want but computers need it to be exact.

 

That's exactly what I would need.... now do XOR Gates handle 24vdc

 

ok so most XOR GATES seem to operate on less than 12vdc would it be safe to assume I can use a resistor to drop the voltage going into the gate then use a capacitor to boost the voltage back up to 24vdc after the gate

 

You can use voltage dividers with zener diodes on the bottom = input side to make certain that the voltage you see is correct.

I still don't know if you really want to kill the output when you have both inputs.

Blueroom suggested that you do a flowchart, and I would add to that a truth table for your expected outputs.

Also realize that the LM293 does not really care if you pull both sides of a bridge low or high.

Try and do a circuit diagram for your design as well.