PIC16F685 RA4/RA5 pins

[Bruce]

I think you may be confusing MicroCode Studio editor with your programmers software.

I'm sure you selected something like meProg software Options, More Options, then
Set Options to Defaults..., which reset programmer options. It most likely was not
loading & using config settings embedded in your .HEX file.

If you comment out all config options in your code, compile, then program, you'll see that
all config options are at the default unprogrammed settings. This leaves /MCLR ON, sets
the oscillator to external RC with clock out on OSC2, and produces exactly the same
scenario you were seeing.

I duplicated it exactly by doing the same thing here. Somewhere along the line you had
changed your programmer settings to not use config settings in your .HEX file - or not
program them.

Check the attached graphic. I commented out the config statement in the example above,
compiled, and launched the programmer. Check the config settings.

The PIC is still going to run because there is no external RC clock, it assumes the external
osc has failed, and switches over to the default internal 4MHz osc, and keeps going.

But now you have Fosc/4 out on OSC2, and a ping signal on OSC1, which is the internal
driver ping to tickle the external RC osc, which you don't have...;o}

Check the diagram in the datasheet under RC OSCILLATOR MODE for a drawing of what's
going on with these two pins when this osc mode is selected.

[Adrian]

Yes thanks Bruce. Slip of the tongue between Editor & Programmer. It was the Programmer I set back to default options. I guess I must have jiggered one of the default settings which as you say stopped it loading and using the embedded settings.

Thanks for explanation of clock settings on the 16F684. I have looked up the datasheet and see exactly what you mean.

It's a long and slippery road but a great learning curve..........

Regards

Adrian