Code running 19 times slower than intended

[falingtrea]

If you want to be able to run at lower than 4.2 volts you should probably be using the LF version of the part. Looks like the LF version will work from 2V to 5V with slower clocks the lower the voltage goes. Some F parts may work lower than the 4.2V spec, but there may be some that flat out won't.

[Bruce]

Dave,

Are you sure you're not using the LF version running at 3V?

[mackrackit]

Yes, I just doubled checked, again.

Do not laugh at the messy board, everything on it runs at 3.3 volt. Another interesting thing is this chip can also be programmed at 3.3. I have the PicKit2 feeding a LM317. The PicKit is fooled into thinking it is running at 5 volts.
Along with the SD card there is a MAX6675 and a DS1337. Working on a PYRO LOGGER.

And the data sheet is a bit miss leading?
I take the extended range (LF) as going down to 2 volts.
I guess I could have a batch that was labeled incorrectly?

[Bruce]

Are you running it at 48MHz @ 3V?

[mackrackit]

Yup, with a 4MHz external purchased from you

DEFINE OSC 48
@ __CONFIG   _CONFIG1L, _PLLDIV_1_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
@ __CONFIG   _CONFIG1H, _FOSC_HSPLL_HS_1H
@ __CONFIG    _CONFIG2H, _WDT_OFF_2H & _WDTPS_512_2H
@ __CONFIG    _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H 
@ __CONFIG    _CONFIG4L, _LVP_OFF_4L & _ICPRT_OFF_4L &_XINST_OFF_4L

[Bruce]

Well that's interesting. So much for those worthless voltage-to-frequency graphs in those darn data sheets ehh...;o)

If it works - it works - can't argue with that.

[rsocor01]

I'm also running my PIC18F4550 with a 4MHz external oscillator at 3.0V. I use the HSPLL setting for the oscillator. The define osc line is

DEFINE OSC 48

and it seems to be working fine. I'm feeding data to a color GLCD and it does it very quickly.

Robert