Simple program hangs up when I add Xfreq and clkmode

Potato

The simple program:

'' File RP_Servo1.spin

CON

_xinfreq = 5_000_000
_clkmode = xtal1+pll16x


PUB LedON 'method declaration

dira :=1 'set P4 as output pin
outa :=1 'turn on LED

repeat 'endless loop



When I add the three lines:
CON
_xinfreq = 5_000_000
_clkmode = xtal1+pll16x

the Propeller seems to just not work, ie will not execute and turn on the led.

If I comment out _xfreq and _clkmode the program runs and turns on the led.

Any ideas?

Phil Pilgrim (PhiPi)

You haven't said what your configuration is. Which board are you using? Do you have a 5MHz crystal attached to XI and XO?

-Phil

Phil Pilgrim (PhiPi)

Jon,

I think the bracketed "4" disappeared and caused the font to change size.

-Phil

MagIO2

Aren't this the symptoms of a killed PLL? Read about that in other thread - so long did not have this problem myself. But in case you did something wrong with the power supply, you can kill the PLL. This Prop then will only work in buildin RC-mode.

So, if you are sure that the crystal works, this might be the reason.

Phil Pilgrim (PhiPi)

MagIO2,

It sounds suspicious, but I didn't want to bring that up before I knew more about his configuration. Hopefully, it's something more benign.

-Phil

SRLM

When a program seems to hang for no reason, I always check to make sure that I haven't lost the crystal.

Potato

OK, Found the problem. I am using a breadboard, 40 pin dip Prop chip with 5 MHz crystal. something on the breadboard is flakey.
When you put me on the trail of the PLL, I changed the PLL setup to PLL8X and the code works.
Somehow the sloppy wiring of the breadboard prevents the PLL16X from working.
I took the same code and ran it on a Parallax demo board and it works fine.
Thanks to all who answered.
Potato

MagIO2

Maybe PLL16X would work with other XTAL settings then? My understanding is that the XTAL defines which internal capacitors to use. If your breadboard adds some parasite capacitance, then another XTAL setting might work.