Compiler, pic16f688, FCMEN fuse

TomX · Joined: 13 Sep 2005 Posts: 2

We are using the PIC16F688 with the CCS compiler. On this chip, we want to disable the automatic clock switchover from external to internal during clock failure. This is done with the FCMEN parameter in the config string. Examples we saw show NOFCMEN as the thing you put in config string.

After programming the chip, it shows that FCMEN is still active.

Any ideas on what we are doing wrong?

thanks,

TomX

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Post your compiler version. This will be a number like 3.191, or 3.233,
etc.

TomX · Joined: 13 Sep 2005 Posts: 2

We are using IDE 3.43 and compiler 3.207

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

I tested PCM vs. 3.233 with the simple test program below, and it fails.
The .LST file always shows FCMEN (and the config bits also show it).

I compiled it for the 16F687 and 16F88, and it works OK.
I think the problem is probably in the settings in the Devices.dat file.
Since you have PCW or PCWH, you can use the Device Editor to fix this.

Look at this screen-shot of the Device Editor.
http://www.ccsinfo.com/pix/Device%20Editor.gif
In the upper right corner, it shows the fuses. You should load the
16F688 file and check the settings for FCMEN and NOFCMEN.
Check if the MASK and the VALUE are correct. If not, then change them.