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need info on how much power can a stamp provide — Parallax Forums

need info on how much power can a stamp provide

BadgerBadger Posts: 184
edited 2008-10-22 21:19 in BASIC Stamp
Hello

i am needing to know how many L.E.D.'s can i hook up to each pin on a bs2 with out over loading it. I am wanting to hook up a light chaser circuit like for Christmas. I dont want to harm the stamp .. I know when you put an L.E.D. in a test circuit to see if the led comes on. So how many L.E.D.'s does it take per pin to not have a resister. How many L.E.D.'s per stamp and as i asked above per pin can it handle .

Badger

Comments

  • metron9metron9 Posts: 1,100
    edited 2008-10-17 21:25
    See http://www.parallax.com/Portals/0/Downloads/docs/prod/stamps/BasicStampFAQ.pdf

    But you need a resistor

    How much current can the I/O pins handle?
    On the BASIC Stamp I and BASIC Stamp II, each I/O pin is capable of sourcing 20 mA and sinking 25 mA. The
    total across all I/O pins should not exceed 40 mA source or 50 mA sink at any given time, however. One
    exception to this rule exists with the BS2-IC. If the BS2-IC is powered by an external 5-volt regulator capable of
    delivering at least 100 mA, the total across each group of 8 I/O pins (0 - 7 and 8 - 15) can reach 40 mA source or
    50 mA sink providing a total of 80 mA source or 100 mA sink overall. The BASIC Stamp IIsx’s I/O pins can
    source and sink 30 mA, and the total across all I/O pins should not exceed 150 mA.

    If you are going to have long wires attached to the stamp pins to each LED or a bunch of wires then you may blow up the stamp from static electricity if you dont have any resistors protecting the pins.

    Simply use a shift register or transistors or fets, drive those with the stamp pins.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Think Inside the box first and if that doesn't work..
    Re-arrange what's inside the box then...
    Think outside the BOX!

    Post Edited (metron9) : 10/17/2008 9:32:07 PM GMT
  • BadgerBadger Posts: 184
    edited 2008-10-17 22:21
    Hey


    i am new at this so could you explain your message a little further. as to what you said at the bottom of your post . if you would that is

    thanks in advance

    Badger
  • beatsbeats Posts: 17
    edited 2008-10-19 05:05
    yea I am having the same issues, I am new to this too.


    could you or somebody break down the following in more laymen terms,

    On the BASIC Stamp I and BASIC Stamp II, each I/O pin is capable of sourcing 20 mA and sinking 25 mA. The
    total across all I/O pins should not exceed 40 mA source or 50 mA sink at any given time, however.

    what exactly does it mean when they refer to the current as "sourced" or "sinked"?


    I would apreciate that, thank you.
  • MikerocontrollerMikerocontroller Posts: 310
    edited 2008-10-19 07:00
    One way to understand is to think of where the current is coming from. If it comes from the Stamp (such as driving a pin HIGH with a load connected to ground) then the Stamp is SOURCING current. If the current is supplied from the power supply (such as when a pin is driven LOW with a load connected to Vdd) then the Stamp is SINKING current.
  • beatsbeats Posts: 17
    edited 2008-10-20 21:02
    thanks i think I understand it now, but lets say I am "sourcing" pins P10-P15 to a second chip(voice chip), would I need a load resistance in series between these two chips to drive the current?
  • MikerocontrollerMikerocontroller Posts: 310
    edited 2008-10-21 03:35
    · I think you'll have to give more info on the chip you are interfacing to and the function of those pins.
  • allanlane5allanlane5 Posts: 3,815
    edited 2008-10-21 12:36
    Please, please, please, DO NOT use the BS2 I/O pins as a "power source". Each chip you use should have its OWN connection to Vdd. The BS2 has an on-module regulator which is good for about 50 mA -- that's basically two or three LED loads in addition to the BS2 itself.
  • beatsbeats Posts: 17
    edited 2008-10-22 21:19
    The chip I am using is the ISD4004 voice chip and it only needs a 3 volt power supply.
    My project is similiar to this one http://forums.parallax.com/showthread.php?p=659734·except I am·using a BS2 instead of·the SX.

    I am using pins P10-P15 of the BS2 and interfacing them with SS, MISO, MOSI, SCLK, INT,and RAC of the ISD4004.

    I guess my question is: when I·program these BS2 I/O pins to HIGH, what voltage will they send out?· Will it be 5 volts?· And if so would this be too high of a voltage for my voice chip?


    DosMANdan's project did not have this issue because the SX only needed 3 Volts to run, however my BS2 needs 5 Volts.· This is why I am a little confused with this issue.

    Thanks for your help,
    logical
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