> Am I reading the PIC 18F4520 docs correctly that you can only
> assign analog inputs in ascending order?

Yes. Some are not like that, and you can assign any individual pin as
an analogue input on its own

Depending on the circuit, you should be able to temporarily switch
from outputs to inputs if the pin is not left floating. For example if
you want AN5 to be the analogue input and PORTA <4:0> are in
use as outputs, you set PORTA <5:0> as inputs in TRISA and
ADCON1 <3:0> = 1001 to configure AN <5:0> whilst you select
and read AN5 (ADCON0 <5:2> = 0101)

wbr
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