Edward Cooper wrote:

> I'm trying to use my PIC16F687's Tx port on the EUSART as a dual  
> function pin, ie as a connect detect input and as a Tx channel.
> 
> So here's the question, what's the maximum safe loading on the Tx  
> port when its doing RS232, I'm imagining its in the region of 2mA,  
> but I can't find any details on the datasheet, and its seems unlikely  
> it would match the 20mA of the GPIOs...

It /is/ a normal IO pin, even when being driven by the EUSART. The drivers
are the normal port drivers, just the logic is different.

I'm not so sure about the 20 mA though. I haven't worked a PIC in that
range yet. The data sheets mostly talk about 3 mA sourcing and 8.5 mA
sinking. You probably can go further, but that doesn't seem to be
guaranteed.

Gerhard

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