[DSP-10] PLL Problems

Fri, 9 Jan 2004 08:34:07 -0800

Tan Teik:

Please consider disconnecting the PLL from the VCO during your debug.
If you fix the voltage to the VCO's to something stable, like 1 to 4
volts, you can test the range of the oscillator.  Adjust the value of
the resonante circuit until you can manually tune across the 124 to 128
MHz range.  You can perform all of this without having to deal with
downloading test programs onto the board.  AFTER you see the VCO running
properly within this range, re-connect the PLL to the VCO.

For more details, study the instructions at:
	http://users.easystreet.com/rhayward/dsp10/pll_tuneup.html

73
	ARS KA7EXM

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Tan Teik Chuan
Sent: Friday, January 09, 2004 1:18 AM
To: [email protected]
Subject: [DSP-10] PLL Problems

Now, even more strange thing happened.

I was able to lock the PLL at the range of about 100MHz-105MHZ once. I
was 
so happy that I restarted the program hoping that it would lock at the
same 
range again. However, thing didn't happen as expected. It didn't lock.

Not only it didn't lock, it failed to program the shift register 
properly.So, I loaded udiag1 to see whether the serial bus worked. The
LED 
blinked correctly but after first cycle, the Tx LED was on. After second

cycle and subsequent cycle, the Tx LED was off. I suppose this shouldn't

happen.

Troubleshoot still carry on.

Regards,
Tan Teik Chuan

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