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Command PLL circuit via computer

D

Damien Teney

Jan 1, 1970
0
Hello,
I'm building a VHF receiver and I would like to include a PLL circuit to
control the VCO. I've never done it before, so I would like to use the
LMX2337 because I've a lot of doc about it. I intend to to connect it to my
computer, but I don't know to send data to it. Do you know if there are
programs to do it ? or could you help me ?

Thanks a lot.

http://www.national.com/ds/LM/LMX2337.pdf
 
R

Rich Webb

Jan 1, 1970
0
Hello,
I'm building a VHF receiver and I would like to include a PLL circuit to
control the VCO. I've never done it before, so I would like to use the
LMX2337 because I've a lot of doc about it. I intend to to connect it to my
computer, but I don't know to send data to it. Do you know if there are
programs to do it ? or could you help me ?

Well, you could probably bit-twiddle a parallel port to do this but
you'd probably also want to include opto-isolators between the PC and
the chip to avoid close coupling between the RF device and your PC.

What I'd recommend instead would be to embed a microcontroller in your
design and talk to the micro from your PC over a regular RS-232 serial
link. The microcontroller could take care of device initialization and
control as well as perhaps running a front panel display or sending
status information back to the PC.
 
D

Damien Teney

Jan 1, 1970
0
Yep, but my goal was to avoid using a embedded microcontroller. However I've
used google a lot this afternoon and I think I will use a PLL IC with
parallel interface, that we can command via simple dip-switches. I think
that's the easiest (and cheapest) way.
 
J

Jean-Michel Friedt

Jan 1, 1970
0
I'm building a VHF receiver and I would like to include a PLL circuit to
control the VCO. I've never done it before, so I would like to use the
LMX2337 because I've a lot of doc about it. I intend to to connect it to my
computer, but I don't know to send data to it. Do you know if there are
programs to do it ? or could you help me ?

Isn't that the point of DDS ?
Check the Analog Devices AD9850 on www.analog.com, and if you
search for that same reference on the web you will find a small
program for controlling it using the parallel port (I think DOS
based).
I was interfacing the AD9850 to an H8 microcontroller and tested
the connexions to/from the AD9850 using DOS based and linux based
control software controlling the parallel port. I can send these
to you if necessary.

Jean-Michel
 
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