The confi fuses for pic18f4550 in Epic programmer

[sammy]

Hi all:
I am having a hell of a time programming the pic18f4550 due to its so many clock options. I have been able to get every thing to work if i use a 4MHz ceramic resonator and the XT option from the fuse config menue. The problem occures when i use a 20MHz resonator.
I use the command Define osc 20 but the timing is still off. I tried to send serial data and the timing is all off.
any ideas

thanx


sam

[ErnieM]

Time for a sanity check. Forget your project for a while, make something simple work.

Measure the clock frequency. Is it really 20 meg?

Make a loop timed with a PAUSE to wiggle a pin up and down. Is it the right period?

Sorry I can't be of more help with the serial commands as I've yet to use them.

[Bruce]

Be sure to set HS in config word. This forces the PIC oscillator drive output
to a higher level required to drive the high-speed oscillator.

The default config word osc setting in 18F4550.INC header file is for XT.

Look in your PBP directory for 18F4550.INC, and change XT to HS, or change
XT to HS with your programmer software before programming the part.

[sammy]

Thanx for the reply Bruce. The problem I am having however is not with the compiler but the programmer. In the MElabs programming softwear for the EPIC I can change the configuration fuses. My understanding was that with a 20MHz ceramic resinator if i select Osillator type as HSPLL for Pic18f4550 and use the pll divisions as 5 with the mcu clock division as 2 this should give me a frequency of 48MHz. This is according to the data sheet. however when i do this and try to send data through port B.7 at 9600, the data actually comes in at 115200. I do define the osc at 48 in the program. this is the problem.
any ideas
thanx
sam

[Bruce]

Sorry. Your original post indicates DEFINE OSC 20 with a 20MHz osc. I didn't know you were trying this at 48MHz.

If you're changing config settings with your EPIC software, and you have the "Reread File Before Programming" and "Update Configuration From File" options checked, then it's going to reload whatever config word settings are embedded in your .hex file before programming the part.

You should click Save before programming to use whatever config word changes you made. Then program it.

With a 20MHz crystal, PIC18F4550, and this osc configuration;

CONFIG PLLDIV=5,CPUDIV=OSC1_PLL2,FOSC=HSPLL_HS

This works perfectly at 9600;

SEROUT2 PORTB.7,16468, ["TEST",13,10]

If you prefer to use 20MHz without HSPLL, just change FOSC=HSPLL_HS to FOSC=HS and DEFINE OSC 48 to DEFINE OSC 20.

This also works 100%. At least on my board.

[sammy]

Again Thank you very much Bruce but I still cant get the thing to work. I am getting lcoser though. when you say to write the
CONFIG PLLDIV=5,CPUDIV=OSC1_PLL2,FOSC=HSPLL_HS in the softwear, do i need to add a @ before the word config. I tried this with both the @ and without and the compiler gave me errors both times. what is the exact wording that i need to type into my program
thanx again
sam