The assignment of the BUSY and POUT pins to the microcontroller had
changed from the previous version to the new version. User amigos500 on
the a1k forum noted that if the assignment of those two pins had not
changed, then it would be easier to patch an old PCB to work with
the updated design.
After testing, it seems that the old pin assignment of BUSY and POUT
works equally well with the updated design, and I therefore reverted
the assignment back.