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Connecting a 3.3V device to the S2 — Parallax Forums

Connecting a 3.3V device to the S2

W9GFOW9GFO Posts: 4,010
edited 2010-12-09 21:41 in Robotics
I intend to hook up an XBee to my S2. The hacker port only supplies 5V so it looks like I will need to add a regulator. According to the schematic the 3.3V regulator on the S2 is only rated for up to 150 ma, not enough for the XBee (Pro).

Also, there is a level translator between the hacker port and the Propeller chip. Will the 3.3V signals from the XBee pass through the level translator just as well as if it weren't there or should I bypass it?

Rich H

Comments

  • WhitWhit Posts: 4,191
    edited 2010-12-09 06:59
    Good questions Rich. Since the S2 is Open Source - I am confident that all will be revealed. Can't wait to hear.
  • sylvie369sylvie369 Posts: 1,622
    edited 2010-12-09 07:33
    Just a comment - the regular (that is, non-"Pro") version of the XBee will be perfectly happy with a 150 mA regulator, as even in transmit it only requires about 55 mA. That is assuming, of course, that you don't have other devices drawing from that same regulator.
  • W9GFOW9GFO Posts: 4,010
    edited 2010-12-09 11:09
    I'm using the -Pro version. I decided to use one of my PowerTwigs, it worked really well. For now I have the data lines going into the Hacker port. Haven't tested it yet.

    attachment.php?attachmentid=76186&d=1291892724

    Rich H
  • bdickensbdickens Posts: 110
    edited 2010-12-09 14:30
    Once you crack this, please publish the circuit. I've got the same requirement. Thanks
  • ercoerco Posts: 20,256
    edited 2010-12-09 15:10
    First (documented) S2 mod honors to Rich! WooHoo!
  • WhitWhit Posts: 4,191
    edited 2010-12-09 16:41
    erco wrote: »
    First (documented) S2 mod honors to Rich! WooHoo!

    Not to mention it looks really really cool!
  • W9GFOW9GFO Posts: 4,010
    edited 2010-12-09 17:12
    Thanks guys, let's just hope it works.

    Rich H
  • WhitWhit Posts: 4,191
    edited 2010-12-09 17:34
    I have faith...
  • WBA ConsultingWBA Consulting Posts: 2,934
    edited 2010-12-09 20:46
    If you wanted, you could cut the PowerTwig just ahead of the 5 volt header location to further reduce it's footprint. Just make sure that the edge is clean so that the ground plane and any top traces aren't too exposed. I may look into modifying some PowerTwig PCBs and make them into single regulator PCBs for this purpose if people were interested. (I have about 80 built PowerTwigs and 300+ fabs right now). I can coat the edges with a soldermask pen after cutting to prevent the copper exposure risk. You could also use a bit of clear nail polish.
  • W9GFOW9GFO Posts: 4,010
    edited 2010-12-09 21:05
    I considered cutting it but decided against it because 1, it doesn't use up any space that means anything and 2, I may want to repurpose it someday. If only there were an additional 5V header then cutting it would yield two useful regulators.

    As I think about it more maybe I would cut it if I were to do it again, if for no other reason than to further the "hackiness" of the project.

    attachment.php?attachmentid=76205&d=1291929525

    Rich H
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-12-09 21:41
    Rich,

    'Beautiful, elegant job! Now, how about trying to upload S2 programs via that XBee module. See here:

    -Phil
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