While timing isn't critical, I am interested in seeing how fast I can make this system run. I have tried removing all port manipulation and using pinMode() and digitalWrite() and it didn't solve the problem.
The comment in the code isn't the most descriptive. The minimum required by the converter is 400 nanoseconds but the delay as implemented is closer to 500 nanoseconds. I will make the delay close to the maximum that the converter specifies to see if that increases the accuracy of the conversion. Thank you for the suggestion.
Greg