I also need to work out a pos and neg trigger combined as some Honda CDI need to see both. Most of the Yamaha that I make I need them completely seperate to do testing on the CDI. This will all be done in hardware.
It's too bad the DAC did not work out for this purpose. Are you certain that with what you know now, you can't get it to work. The code is ready to go 
By the way I assume you have a Australian Cattle Dog ? I have a 1 1/2 year old male and he is, well a typical cattle dog but with an attitude.
Mine is long gone, but I think they all have attitudes. They are very tough breed to have. I never had the patience to properly train mine, and she did what she wanted to do. Totally a mind of it's own.
Mine was a terrible watch dog-- aggressive but not not alert. No alarm barking, but she'd bite when a stranger sneaked up on her.