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serout stuff — Parallax Forums

serout stuff

damiondamion Posts: 39
edited 2007-06-01 00:32 in BASIC Stamp
Hello,

So what I would like to do is link 2 bs2p's with seperate vin and vdd sources to one transciever and have them both send data via the transciever. From the serout documentation I get the impression that this is how I wire it up. But I have already burntout one pin trying this. Any advice as far as code is concerned?

Thanks,
Damion
doc
doc
schematic.doc
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Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-05-31 03:52
    A couple of thoughts:

    1) I don't know how much current the Maxstream transceiver takes, but it's probably more than the regulator on the Stamp can provide. A Stamp can normally provide only about 50ma of +5V and the Stamp itself takes some of that. You can't parallel two Stamps to get more current either.

    2) It's dangerous to directly connect two Stamp pins to each other (pin 8 on one Stamp to pin 7 on the other). Both Stamps will initialize their I/O pins to input mode and, if you write your programs properly and make no mistakes, you can do without a protective series resistor in each lead, but, if you accidentally make both pins outputs and they're in different states (one high and one low) for even a few milliseconds, you may burn out one or both I/O pins. Other than that, you can connect both Stamps to one transmit input with the pullup and whichever Stamp does an output that pulls the transmit line low will control the transmitter (a SEROUT will work too as long as you use open mode). I suggest you use a smaller pullup value. 4.7K is a good compromise for power vs. speed. If you do use a protective series resistor in each Stamp I/O lead, 220 ohms would be fine.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-05-31 15:01
    The main issue I see with your circuit is that it appears as though you’re powering the BASIC Stamps from both the VIN and VDD which you cannot do. That system is mutually exclusive. Use one or the other but not both.

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    Chris Savage
    Parallax Tech Support
  • SumanSuman Posts: 19
    edited 2007-05-31 17:08
    Are you working with the XBee module which works on ZigBee protocol??
  • damiondamion Posts: 39
    edited 2007-05-31 23:06
    Thanks guys,

    Suman I am working with the xstream module.
  • damiondamion Posts: 39
    edited 2007-06-01 00:32
    I am actually still a little confused about the open mode.
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