PDB pulse generator question
paulc22
Posts: 7
Hello.· I am trying to test my program which uses the COUNT instruction to count pulses on a pin.· I want to put some pulses on the pin, and I believe I could/should use the pulse generator on my professional development board.·
Trouble is, I don't know how to use the pulse generator.·
The PDB documentation for the pulse generator is very sketchy (well, actually it lacks a schematic), and it has only 3 short sentences on this feature.·
The PDB schematic doesn't help me much either.· I've read a lot of schematics before, but this one is confusing.· It has lots of pin connections at "GPIO" pins.· I guess GPIO means general purpose I/O, but I still don't know how to actually use it.·
All I want to know is how to use the pulse generator.· I assume it's already grounded on the board.· This seems like such a basic request.· Parallax obviously went through a bit of trouble putting the feature on the board.· Am I the only newbie who cannot figure this out?·
A simple paragraph indicating what we're basically doing, plus a good schematic, plus some sample code would be a GREAT benefit.
Please help.
Paul C
·
Trouble is, I don't know how to use the pulse generator.·
The PDB documentation for the pulse generator is very sketchy (well, actually it lacks a schematic), and it has only 3 short sentences on this feature.·
The PDB schematic doesn't help me much either.· I've read a lot of schematics before, but this one is confusing.· It has lots of pin connections at "GPIO" pins.· I guess GPIO means general purpose I/O, but I still don't know how to actually use it.·
All I want to know is how to use the pulse generator.· I assume it's already grounded on the board.· This seems like such a basic request.· Parallax obviously went through a bit of trouble putting the feature on the board.· Am I the only newbie who cannot figure this out?·
A simple paragraph indicating what we're basically doing, plus a good schematic, plus some sample code would be a GREAT benefit.
Please help.
Paul C
·
Comments
As this is a more advanced board there is less documentation/tutorials about it. The pulse generator is always sending out a pulse at the frequency listed below the LED lit up. By default at power up the pulse is 1 Hz (Square Wave). Each press of the button cycles through the frequencies (1 Hz, 10 Hz, 100 Hz, 1000 Hz/1 kHz). There really is nothing more to it. Those are the only frequencies you can get. Take care.
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Chris Savage
Parallax Tech Support
paul
It seems like this is something that recently stopped working? It is hard to say what might be happening. To date I haven’t seen the pulse generator fail on any of these boards.
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Chris Savage
Parallax Tech Support
The PDB documentation in the pulse generator area is very sketchy.· Do you have any more info.· It appears to use a processor IC to do it, and I was surprised it didn't just use a timer or similar (LM555).
Thanks.
Paul
There is no troubleshooting you can do, save testing the output frequency at each value. The reason for using the PIC instead of a 555 is that the PIC can handle changing the output by using a button press. This would be significantly more difficult to do with a 555 Timer. You can run a wire from the signal generator output into the audio amplifier input. When the pulse is on 1 you should hear a kind of tick from the speaker. When the setting is on 10 you should hear a rapid clicking. When it is on 100 you should hear a low tone and on 1000/1K you should hear a higher pitch tone. Take care.
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Chris Savage
Parallax Tech Support