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HomeWork Boards

ajwardajward Posts: 1,130
edited 2012-07-26 19:50 in BASIC Stamp
Hi All...

Is there some resource that lists the differences between the various revisions of the HomeWork boards?

I have 2 such boards... the first is labeled 2002 - 2007 Rev E with a serial port. The second is labeled 2002 - 2010 Rev A with a USB port.

Not an urgent question... just wondering.

Many Thanks,

Amanda

Comments

  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-07-02 12:14
    Hi,
    I was trying to sort this out because my voltage regulator seemed to not be documented. I have a Rev D. board, RS232 with a LM2940 regulator.

    The two items that seemed to be different are [a] a choice between RS232 versus USB and the size and kind of the voltage regulator. Everything else seems to have stayed the same.

    Parallax has never gotten into issuing formal listing of changes with each revision of an item. Other people do it and it saves a lot of back and forth searching and asking. To make matters a bit more awkward, some of the other vendors on-line are providing older documents AND there seems to be a series of errors in the explanation of the differences.

    What to do? It is easiest to just look at the chips and Google the part number on top of the voltage regulator. I am pretty sure what Parallax intended to say was that Version B was a special low power version with only 50ma provided by a LM2936 regulator. The others have a higher power voltage regulator. Both the LM2936 and the LM2940 have reverse polarity protection and that is another important feature. The7805 regulators do not and I've destroyed quite a few by getting plus and minus reversed.

    The special low power board is nice for SLEEP mode that might allow you to extend the life of one 9V battery to thousands of hours in a loop that goes to sleep and wakes up to do something then goes back to sleep, but that really is a low priority use for most beginners.

    The 24pin BS2 will do the special low power, too.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2012-07-03 08:14
    Rev A may also be a 50ma low power board. If will likely be very obvious by the tiny size of the regulator. It is the same one used on the 24pin BS2.
  • BansheeMarcBansheeMarc Posts: 2
    edited 2012-07-26 16:34
    Loopy Byteloose wrote: »
    Parallax has never gotten into issuing formal listing of changes with each revision of an item. Other people do it and it saves a lot of back and forth searching and asking.

    I just got my first ever microcontroller and I'm a total newbie (I just finished lesson 1). My Homework board is a rev "F". Could you, or anyone, point me in the right direction of finding this info that other people gather? Thanks for any help.:smile:
  • Mike GreenMike Green Posts: 23,101
    edited 2012-07-26 17:59
    There's no repository of this sort of information. Most of the time it doesn't matter since the board revisions are usually for manufacturing improvements, not any functional change. This particular case (50mA regulator to higher current regulator) was due to customer requests. The 50mA limit was just too low. The newer revision provides a higher current rated regulator, but you're usually limited to maybe 150mA due to heat dissipation limitations.
  • BansheeMarcBansheeMarc Posts: 2
    edited 2012-07-26 19:50
    Many thanks for your time and info Mr. Green.:thumb:
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