Pls How can I make 16F877A use 15MHz Xtal

[skimask]

My understanding is that to use 15 MHz crystal i need to include
DEFINE OSC 15
at the top of my pic basic pro codes
and that I needed to edit the 16F877A.INC file on my C: drive and replace XT_OSC with HS_OSC.
I have done this. Is there anything I am not doing? Thanks

XT vs. HS. Check the datasheets
You have to reconfigure your PIC to run the 15mhz oscillator.

And check your PBP manual for the correct use of:
DEFINE OSC 15

[paul borgmeier]

Skimask is hinting that you read section 7.1 of the manual (and pay particular attention to the table)

... and I think he wants 15MHz, not 15mHz .... 1,000,000,000X difference

[skimask]

Skimask is hinting that you read section 7.1 of the manual (and pay particular attention to the table)

... and I think he wants 15MHz, not 15mHz .... 1,000,000,000X difference

Good call. At least I didn't say 15uhz...or 15phz...or 15fhz and keep going...and going...and going...

[Archangel]

Skimask is hinting that you read section 7.1 of the manual (and pay particular attention to the table)

... and I think he wants 15MHz, not 15mHz .... 1,000,000,000X difference

Hi Paul,
_ D'oh I think I missed something here, mHz != MHz by a billion times, What the heck is mHz if not megahertz? Please forgive my American ignorance of this little part of the Metric system but they didn't teach that in school in those days.
Thanks
JS

[skimask]

Hi Paul,
_ D'oh I think I missed something here, mHz != MHz by a billion times, What the heck is mHz if not megahertz? Please forgive my American ignorance of this little part of the Metric system but they didn't teach that in school in those days.
Thanks
JS

Unwritten rules I think...Probably hinting that:
mhz = milli hertz
Mhz = mega hertz
kinda like
bps = bits per second, while
Bps = could be taken as BYTES per second

I would take it that way if I didn't have anything else to base it on...meaning if I didn't know we were talking about megahertz I might think we might've been talking about milli hertz...

[paul borgmeier]

Hi Joe,

I was being more of a smart @$$ than anything else - I knew exactly what was implied by mhz. However, the m versus M thing is what I was taught in school and is the accepted standard for abbreviations

http://en.wikipedia.org/wiki/Milli

I should have kept my 10^9 comment to myself and instead said "thanks skimask for helping so many people learn to fish instead of just giving them the fish!" You have been getting a lot of "thanks" from these fishermen (or should I say fisherpeople) as of late.

Ozzie, did you get your PIC to run at 15MHz?

[skimask]

I was being more of a smart @$$ than anything else - I knew exactly what was implied by mhz. However, the m versus M thing is what I was taught in school and is the accepted standard for abbreviations

I knew what ya meant and what you were getting at. Sometimes, it's obvious, sometimes not. I know I've been tripped up by the 'bps' vs 'BPS' thing more than once. And I spent the best 4 years of my life in 6th grade!

(grumpy ol' man)
Back in my day...we didn't have 'METERS' and 'GRAMS'...we had 'a long ways' and 'heavier than hell'...and (slams hand on table) 'WE LIKED IT THAT WAY'...

[Archangel]

I knew what ya meant and what you were getting at. Sometimes, it's obvious, sometimes not. I know I've been tripped up by the 'bps' vs 'BPS' thing more than once. And I spent the best 4 years of my life in 6th grade!

(grumpy ol' man)
Back in my day...we didn't have 'METERS' and 'GRAMS'...we had 'a long ways' and 'heavier than hell'...and (slams hand on table) 'WE LIKED IT THAT WAY'...

Back in my day they called it CPS and didn't worry about less than 1 whole cycle.

[Acetronics2]

XT vs. HS. Check the datasheets
You have to reconfigure your PIC to run the 15mhz oscillator.

And check your PBP manual for the correct use of:
DEFINE OSC 15

geeeee !!! What a wonderful forum is has become these days ...

after all these years, I didn't know there was a DEFINE OSC 15 ...

12 or 16 only available ... too bad !!! ( Manual p. 170 ... )

but ... PBPIC libs can be modified, of course !!! ... or time related functions re-calculated ... isn't it ???

Alain

PS: Sorry Ozzie, but it will be VERY difficult to run off-the-list frequencies with straight PBP ... try 16 Mhz !!! it will be so much simpler ...

May be some ones here could explain you how to modify the PbPlib files ... to run a True 15 Mhz Xtal !!!

I'd really love to read them too ... humour.