You only need a real RS-232 driver if one or more of the following is
true:

Your device needs static protection on the rs-232 port
Your device needs to fully comply with the RS-232 standard
Your device needs to be compatible with 100% of RS-232 equipment (not
just 70% of established, or 99% of newer equipment)
You are using high baud rates and long lines
You want to mention rs-232 anywhere on the packaging, product, manuals,
marketing literature, etc

In short, one offs and hobby projects (even simple kits) are fine
without one, but I wouldn't bet a commercial product on the tradeoff.

-Adam

Kevin Olalde wrote:
>
> I've directly connected a PIC16F84A to various serial devices, multiple
> PCs, Palm Pilots...  and in all cases, with a short cable, I've been
> able to send data to the device from the PIC, using no line driver.
>
> I've also used a 22K resistor between a Palm and the PIC and was able to
> read from the Palm, with no external line receiver, such as a MAX233.
>
> So, do I only need a device such as a MAX233 in cases where I need
> longer cable lengths or if the serial device won't tolerate TTL levels
> as valid RS-232 input?
>
> Thanks for any advice (and sorry if I've mucked up the terms),
>
> Kevin
>
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