It's extremely difficult to read an arbitrary frequency using the parallel port on modern computers. It's best to run an external counter for a known period of time (need a dependable time base) and then read the counter when it is complete.
hi,
The drawing isnt very clear, but the collectors of the two motor drive transistors are connected to +/-12Vdc, so the motor should get a voltage -0.7V less than what is coming out of the Serial Port TXD pin.
If the Serial TXD swings +/-12V then the motor should get +/-11.3V approx.
hi,
The drawing isnt very clear, but the collectors of the two motor drive transistors are connected to +/-12Vdc, so the motor should get a voltage -0.7V less than what is coming out of the Serial Port TXD pin.
If the Serial TXD swings +/-12V then the motor should get +/-11.3V approx.