RS232 splitter cable
There are various RS232 splitter cable schematics around, but the one that I find the most charming is displayed on the picture below.
Thanks to resistors (about 10kohm) connected in parallel to diodes, the circuit above feeds negative voltage level to masterís RX line during idle state or when Ďonesí are sent. Of course, because of these resistors some current is drained into the non-talking slave but drivers are usually capable to cope with it.
The circuit is so simple that there is nothing more to say about it. Still, I want to tell some general stuff about the RS232 serial line:
The USB takes over and these days the RS232 can only be found on old computers. Unfortunately I donít find USB charming at all. It is too difficult to use (from programmerís perspective). It doesnít seem that handy for playing.
Danijel Gorupec, 2012