Setting Up Internal Oscilator Block for PIC16F87

[elcom]

Hi,

I would like to ask, if anybody know how to setup Internal Oscillator Block in the PIC16F87. Shall I have to use direct SFR programming, or it is possible to do using implemented “C” commands. I need to use internal clock 8 MHZ. In case of use direct SFR programming what is the best way to do it?
Thank you very much in advance,
Ioannis

[john cutler]

I found that the CCS header for the 16F88 was missing the internal osc settings. I wrote CCS and the person there replied saying that this would be corrected in the next compiler release. Meanwhile, I used assy SFR bit setting to accomplish this. Seems to work fine.

Download the data sheet pdf from Microchip's site. It's pretty self explanatory.

jc

[elcom]

Could you please send send me some line of your code just to see how you have done it.
thank you in advance
rgds
ioannis

[john cutler]

Well, what I did was to set the CCS #fuses directive the way I wanted (except for oscillator)

#fuses HS, NOWDT, NOLVP, NOMCLR

then I compiled the code and looked at the .lst output file on the bottom at the configuration fuses. (The compiler added other options as well)

the configuration word was listed with a value of 3702

If you look at page 129 or the .pdf, you'll see a description of the config words - the address is 0x2007 which is above the normal memory. Your can access it with a #rom statement at the beginning of your code.

bits 4, 1 and 0 of config word 1 control oscillator selection.

for my purposes, I ended up with

#rom 0x2007 = {3711}

which gave me internal osc with clk ouput on pin A6

I hope this helps.

jc

[elcom]

Thank you!
I'm going to impleent is right now.
regards
Ioannis

[john cutler]

Well, I just checked and CCS posted a new version of the compiler 3.177 which insludes an udpataed header file for the 16F87/88. Now, INTRC and INTRC_IO are listed.

Try it out.

jc

[elcom]

I saw it also. But in any case I tested your solution, whitch is working.
Thanks
Ioannis

[troy]

Thanks
#rom also works for disabling the Fail-Safe Clock Monitor and the Internal External Switch Over mode
#rom 2007 {0x00}