Hi all,
Finally got this working - thanks again for posting the project.
The default value for CKOPT is 1 and I believe it needs to be set to 0 to get the external oscillator working. At least this is what got it working for me. These were my fuse settings:
Low: 0xFF
High: 0xC9
This isn't the same as what is shown in the fuses image - but the fuse settings above work for me and give me accurate FPS readings.
I also had to set a low value for R11 to increase the led irradiance and get the PD2/3 voltages down towards 2V. R11 for me is around 37 Ohms which means there's around 68mA going through the LEDs which is probably a little much? Perhaps my LED's and Phototransistor aren't matched very well.
I've posted by board below... not as pretty as some of the others, but this is a first for me! After destroying an LED with a BB, I decided to install a tube, which itself has taken a few hits!
Thanks again