Message-Id: 14080_ha5kfu
From: ha5bwh@ha5kfu.#bp.hun.euro (Istvan, Retaller)
To: piclist@mitvma.mit.edu

Ints Mikelsons asks:

Have anybody tried to connect PIC to PC COM port directly? How does

schematic look like?



Hi,

I built a few different boards connecting PIC to PC. Unfortunately I'm

unable to remember where the info came, but it says, PC's RS32 is of a

"shifted-zero" level port, which means you can drive it with TTL levels.

For the PIC input port I used to connect a 22k...100k serial resistor

to limit incoming level swing to appropriate level. You may forget

clamping diodes, because PIC's input diodes handle this problem.

For PIC output I use another serial resistor, value is about 100 ohms.

This is just save PIC against accidental shorts sometimes I make

during my job.

It was not tested at a lot of PC-s, but I'm sure, 15-20 PC's already

worked this way quite correctly.

                                   Istvan