froncio@caip.rutgers.edu (Andy Froncioni) (06/26/91)
I'd like to do A-to-D from a PC/AT game port, for financial reasons. I only need very slow speeds, so I think I'm on safe ground. From my understanding of the game port, it is basically a 555-timer running in astable mode and whose pulse frequency is set by the charge-up of a capacitor in an RC circuit. The R in this circuit is the joystick potentiometer and the whole thing is hooked up to +5v. I figure it should be possible to substitute the analog signal instead of the +5v and use a fixed resistor instead of a pot. to "trick" the 555-timer into modulating its pulse frequency linearly with the analog signal. Has anyone done this before? Can soem one help me with making sure that the zero-offsets and the full 0-5v input range is covered? Thanks, Andy -- Andy Froncioni CAIP Center Parallel Computing Lab froncio@caip.rutgers.edu Rutgers University, Piscataway, NJ