USB Interface

[Matthew]

I am looking for an USB (or serial) interface and program which will
allow me to do the following.

I need to create a 3 volt pulse at a variable rate of between 50 and
400 pulses per second.

I would like to vary the rate of pulse as CPU load (or something like
that) changes.

Any help would be greatly appreciated.
Matthew

 

[Robert Lacoste]

I see two possibilities :
- Either you use a pin of the RS232 port that is under owtware control (DTR
line or similar), and you toggle it directly with a PC-based software, using
on of the timers of the PC to set the rate. Vert easy under DOS, a little
trickier under Windows...
- Or you hook a small 8-pin micorocontroller on the serial or USB port and
you program it to generate the good pulse rate, based on orders sent through
the communication port. Easy with a serial port, a little more complex on
USB...

Cheers,
Robert Lacoste - ALCIOM : The mixed signals experts
http://www.alciom.com