RS-232 Tx / Rx monitoring LEDs?

[Jim Brain]

On 8/18/2015 10:40 PM, drlegendre . wrote:
> As part of my C-64 RS-232 to M15 60mA CL project, I've put together a
> simple MAX232 based interface to connect the TTL levels on the C-64 to the
> standard RS-232 +/- levels.
>
> Is there any reason that I can or cannot install LEDs - on either side of
> the MAX232 converter - to give some indication of line status?
> Specifically, a pair of LEDs, one each for Tx and Rx lines, to blink / etc.
> as line status changes and data moves.
>
> I don't see any obvious issue - but I can conceive of a situation where it
> might screw up the line in some way I haven't considered.
>
> Comments?
Probably "best" to feed the TTL RX and TX lines to a 74'04 and then hook 
the output to a 330 ohm and then the cathode of a LED, with anode going 
to 5V.

But, probably good enough is to just put the diode cathode on the TX and 
RX lines, 330 ohm to 5V, and have fun.

Jim

-- 
Jim Brain
brain at jbrain.com
www.jbrain.com