Hi, may i ask you something?
How can you generate a 3 states ( +Vo, gnd -V) signal (kinda RZ signal) (of course the 200Hz pwm'ed signal is not a problem wth a 51 ...) with the following restrictions... only a 3V batt allowed and output must feed 0.5mA max ...
I was thinking about current sources and a 3state switch array (to draw current from +V to the output load, then the 'hiz' state with the load connected by itself to ground and then the -V state with the current flowing towards -V ... (i mean 3 0 -3V)
But i have some doubts about that solution and in the choice of the correct 3V regulator
(i'll upload the schematic of my idea as soon as i can )
best regards
Tuco!
It all depends on how strong the signal needs to be held to 0V - if it is enough to have a resistor from the output of the RS232 driver to ground. From what little we know, the speed seems to be quite low, so there shouldn't be needed a strong drive to 0V to handle any cable capacitance at least.