On Wed, 12 May 1999 14:48:13 -0400 Andy Kunz writes: >I want to have a PIC switch it's power supply between 5.5V and 3.5V. >Any >ideas? It needs to default to 5.5V on powerup. And it can only use 1 >pin. If you're regulating down from a higher voltage, use an adjustable regulator like a LM317. The PIC pin would be connected through a resistor to the adjust terminal. On power up, the pin is an input so there would be no current through the resistor and the regulator would run at 5.5V. If you make the pin an output and drive it low, then the current through the resistor would set the regulator up for a lower operating voltage. Making the pin an output and driving it high would raise the voltage to maybe 6.2 V, which you may not want. That could be avoided by using the open drain RA4 pin, adding a diode, or using a transistor to switch the resistor. ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]