The LED's in question (the display is already selected) require 20 mA of current, and, though only one is driven at a time, I'd not rely on one of these MCU's to drive the thing, though there are sufficient I/O's to do the job. The datasheet specified the Iol at 25 mA, which may, in fact, be adequate, so we'll look into that eventually.

Handling the fact that the DAC is apparently fixed on P0.1 poses another challenge, which can be dealt with, but you must remember that my former colleague is an analog expert, yet is somewhat uncomfortable with these programmable devices. Additionally, I'm not sure how switching that much current will affect internal noise and therefore impact the DAC accuracy. This can be approached step-wise, in order to allow for the fact I don't have all the details and that the man ultimately responsible for the subsystem is uncomfortable with the technology.

After all, he just called me for some simple advice about family logic that would help him do his conversion and took an interest in using a microcontroller only after I told him the cost would not be unreasonable and would buy him much flexibility. After all, the voltage parameters can be adjusted in firmware rather than in hardware, which is, in itself, a benefit.

RE