Thank you for the replies.
Septillion:
I wanted to use port manipulation for both the DAC and ADC but was having trouble getting it to work on pin PB1. I will revisit this later.
The schematic is attached. The Arduino's hardware SS pin is used for the ADC's CNV pin and the CS is connected to the DAC's CS pin.
The ADC requires a minimum of 400 nanoseconds to complete an acquisition. Timing isn't too critical but I have never used this approach before and wanted to try something new. It works well, at least when the ADC code is used by itself.
MarkT:
It is unusual but if you look at figure 30 in the attached datasheet, you will see that the CNV pin has to be toggled between the acquisition and conversion phases.
Greg
isl26320-21-22-23-24-25-29.pdf (854 KB)