Re : [LabVIEW 8.2][Beginner]See a square signal from the microphone input (or maybe DB-9)

[Ecthelion]

Hello, I would use a signal on LabVIEW which a square signal (0V or 5V) and which has a frequency between ms to s.
I would receave it from the microphone input or with the DB-9 serial port (but some people told me that is impossible so...).
After, I would see the signal on a window and also via a diode which should be green when the signal is 0V et red when it's 5V.

Thanks.

[thomas.baudouin]

Hello,

You can use the sound card microphone input to acquire an analog signal, but be careful with the range (the amplitude of a microphone signal is very small).

The DB-9 is for serial communication, so it can’t be used for acquisition.

I advise you to buy a low cost acquisition device such as the USB 6008.

Regards,

Thomas Baudouin

NI Application Engineer

[preston_johnson]

can you tell us more about the application?  Is this some form of audio measurement, or simply a electrical circuit timing signal.  With details regarding the application, we can provide a better recommendation. 

[Ecthelion]

Hello, for now, my circuit is this.

What I would do is is a big loop with this :

A count which decreases each time the loop restart until it reaches 0 and when it reaches 0, the loop stops. I would be able to choose the number of loop in the user interface.
Actually, what should happen is :

I launch the program with a button, the count decrease of 1, on the program (the one I gave you an image above) the DTR button goes ON. Somethings will happens in an external circuit : the input from the microphone goes to 100mV (Actually, it's 5V but I will decrease it because I know that the maximum input for a microphone is something like 100mV). After some seconds, the input comeback to 0V and, at this time, I would that the DTR button goes OFF. Then, after x seconds that I can define in the user interface, a new loop starts and the count decrease of 1.

Just tell me if it's not clear, I know that my english is not really good.

Thanks.