I have a situation where a single pin on a board must handle digital inputs and analog outputs. The digital input is actually a comparator (LM239A - Open Collector Output).
The problem is, when serving the role of a digital input, I need to be able to tell the difference between floating, and ground. This requires me to have a pullup on the input.
However, in the case where the pin is acting as an analog output, the DAC will be fighting against that pullup. If the pullup is weak, say 100k, is the DAC able to able to overpower it? For reference, the DAC would be driving an analog voltmeter. The DAC output range is 0-10V and is a DC signal (ie, it's rate of change is pretty much zero).
I drew up a simplified example of the input to maybe help.
Thank you for any advice you can provide!