How to reverse polarity on output pulse??

[jellis00]

I am using a 16F690 PIC to control a latching solenoid on a valve. The latching solenoid requires a pulse with positive polarity to open and another pulse of negative polarity to close. Generating the postive polarity pulse at the output pin of the 16F690 is no problem, but I am not grasping how to generate a negative polarity pulse at a pin output. Can anyone advise me or refer me to an explanation? Thanks!

[aratti]

If solenoid current is within pic capability (thing that I doubt) you can use two outputs pins to drive your solenoids. Reversing polarity means having pin 1 high and pin 2 low or pin 1 low and pin 2 high.
If solenoid current is higer then you must use a mosfet Hbridge.

Al.

[bogdan]

Use a H-Bridge...(MCP1404 or TC4424 by example)

...take a look at http://www.robotroom.com/HBridge.html (you have to add some charge capacitors also)

[Acetronics2]

Hi,

Either way you do it ... it will use 2 output pins ...

Or,or,or ... if you use some kind of twin monostable multivibrator on one output, like the ones used to extend or retract the cars radio antennas ... that we found some car generations ago !!!

Alain