18f2550 oscillator problems

[rjones2102]

Hey guys,

Thanks so much for your input. Much appreciated. _CPUDIV_OSC1_PLL2_1L fixed it. I now have the same problem on a 16f88 that I was trying to use with internal osc. It ran about 10 times slower than it should. I can't find any fuses relating to PLL. I was out of internet range (I work on a boat) so I put a resonator in the circuit and fixed it that way. Strange to have the same problem with 2 different chips when there is absolutely no relationship between the problems!! Well, there must be a fuse somewhere I can't recognise!

Thanks again

Rich

[mister_e]

well it's more than set a fuse, you also need to set the internal OSC register. Open the datasheet under OSCCON Section. If my memory serves me well, the default value is set to 32KHz

And then if my memory still serves me well
OSCCON=%01100000 ' will set the internal osc to 4MHz
OSCCON=%01110000 ' will set the internal osc to 8MHz

[rjones2102]

Thanks Mr_e!

I actually tried 8mhz and 4mhz internal using the following settings:

DEFINE OSC 8
OSCCON=%01110000

DEFINE OSC 4
OSCCON=%01100000

My fuse setting was INTRC. I can't find anything else of relevance to osc speed in fuses. It's not a major problem as ultimately I will use a 20mhz crystal but it would enhance my understanding for future projects to be able to use the internal osc.

Cheers

Rich

[mackrackit]

Just a thought, have you read this? Post #6
http://www.picbasic.co.uk/forum/show...ost13087#post6