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BS1 = Output Pin HIGH and LOW actual voltage range — Parallax Forums

BS1 = Output Pin HIGH and LOW actual voltage range

KatyBriKatyBri Posts: 171
edited 2012-04-26 10:39 in BASIC Stamp
Hello, I tried to find this on the Parallax web site. Could someone please tell me the BS1 actual voltage range for an output pin for HIGH and for LOW? I need to connected a reed relay directly to the pin and also need to know how much current the pin can handle (limiting resistor). The voltage ranges will let me select the relay with the correct dropin and dropout voltage.Thanks.

Comments

  • ercoerco Posts: 20,260
    edited 2012-04-25 19:39
    Pretty dang close to 0 and 5 volts. If you have a 5V, 20 mA reed relay (typ 250 ohm) no resistor necessary (but a flyback diode is). 20 mA is the max current source on any pin, BTW. A BS2 homework board won't work, it has built-in 220 ohm resistors.

    PS: A BS2 can SINK 25 mA to ground. Comes in handy sometimes.
  • Mike GreenMike Green Posts: 23,101
    edited 2012-04-25 20:20
    The BS1 uses a PIC16C56A. The datasheet shows the information you want on page 158.
  • ercoerco Posts: 20,260
    edited 2012-04-26 10:39
    This Radio Shack relay http://www.radioshack.com/product/index.jsp?productId=2062478

    can be driver directly off a BS1 pin. No resistor, but use a flyback diode, per http://www.kronosrobotics.com/Anotes/Relays.pdf

    Note that a BS1 Project Board will NOT work, since it has built-in 220 ohm protection resistors that limit current. If you want to use a Project board, you will need to add a small transistor to switch a relay, or else you can use a larger transistor to drive the load directly and eliminate the relay entirely.
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