metafor

hi

i need to control a 20x20 field of small electro magnets with linux. every magnet should be controllable individually, but just on and off.

is it possible to use the serial port for this amount of devices?
how can i control them without building special hardware for the pc?

because i'm a little enoyed to put together 400 small electro magnets, are there any standart parts (magnetmatrix) available?

every advice is welcome.
marc

Nigel Goodwin

For a 20x20 field of LED's you would normally multiplex them, so you would only need 40 output lines. However, presumably you want to be able to address more than one at a time? - while LED's can be pulsed without any visible effects, I don't know how electromagnets would like to treated in that way.

The serial port would probably be the most convenient to use, you would need to build a uP based design to take the signal from the serial port and drive the electromagnets through drivers - either transistors, MOSFET's, or IC's, depending on the power requirements.

Interesting project though!, what is it actually for? - things that come to mind are a reading device for the blind.

fat-tony

Depending... As long as current wasn't being reversed, they should just charge and discharge (the same way inductors do). If the "refresH" rate was fast enough, there'd just be a little bit of ripple across them.