Hi Phil Woods
Please check the following post:
Using PIT channel 0 as a PDB trigger input source
Here are some recommendations for PIT as PDB trigger. I saw in your code that you have enable continuous mode in PDB, when PIT trigger PDB, PDB will trigger DAC according to PDB INT count. Do you need to synchronize the your PDB with PIT, or why do you need to use PIT in your application?
I also recommend you to check the following post:
K22F DAC trigger documentation
PIT, PDB to trigger DAC
They could help you in your final application and understanding PDB module.
Best Regards
Jorge Alcala