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SX48BD FUSEX Register — Parallax Forums

SX48BD FUSEX Register

david31david31 Posts: 4
edited 2014-05-19 11:31 in BASIC Stamp
I have the interpreter chip BS2pe mounted on my PCB and was hoping to run it on a 3.3V PSU as the datasheet states between 3V to 5V, when running at the bottom end of this range to chip goes into an apparent reset mode and communication is halted until the supply voltage goes above 4.2V, is it possible to modify the FUSEX brownout detector value within the Parallax SX48BD to make it 2.6 Volt instead of 4.2 Volt..i.e through a software command within p-BASIC? as i suspect that it set for 4.2V as default perhaps?

---Dave

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2014-05-16 06:50
    No. It's not possible to access the configuration bits from PBasic. I believe you have to use an SX-Key or equivalent programming tool to access these. You might ask in the SX forum.
  • david31david31 Posts: 4
    edited 2014-05-16 06:55
    AH ok thanks for the reply that rules that one out then..can you confirm that the SX48BD has been set for the 4.2V option before being shipped?
  • Mike GreenMike Green Posts: 23,101
    edited 2014-05-16 07:17
    I think that's true. Tracy Allen (EMESystems) had mentioned some time ago that he had special ordered a quantity of BS2pe chips with the brown-out threshold set for 2.6V for operation off a 3.3V supply for a datalogger product.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2014-05-16 10:37
    I believe the current versions of the interpreter use an external brownout detector rather than the on-board one. This allows you to choose your own voltage to a degree.
  • Jeff MartinJeff Martin Posts: 757
    edited 2014-05-16 16:14
    Chris Savage wrote: »
    I believe the current versions of the interpreter use an external brownout detector rather than the on-board one. This allows you to choose your own voltage to a degree.

    Correction: The SX-based BASIC Stamps that have been rated for Industrial Temperature ranges have had their firmware changed so as NOT to use the internal brownout detector and instead use a brownout detector external to the interpreter chip.

    The BS2pe, however, is not one that has had this change made. The BS2pe still has the fuses set for 4.2-volt brownout detection using the SX's "interpreter's" internal brownout detector.

    As was mentioned, we did make a special version of the BS2pe interpreter for 3.3 volt use, but we do not stock those parts and only make them upon special-order request. If you'd like to order those, please contact me ( jmartin@parallax.com ) or our sales department directly to arrange for production and sale of these special-order parts. Sorry, I do not know the stock code.

    NOTE: You'll have to ensure that the other components on the board (EEPROM especially) is compatible with that voltage. They often are these days and I "believe" the one we use is compatible, but I haven't confirmed that.
  • Jeff MartinJeff Martin Posts: 757
    edited 2014-05-16 16:16
    david31 wrote: »
    AH ok thanks for the reply that rules that one out then..can you confirm that the SX48BD has been set for the 4.2V option before being shipped?

    Yes, all the BS2pe Interpreters we stock and use on our BS2pe-IC modules have the option set for internal brownout at 4.2 v.
  • david31david31 Posts: 4
    edited 2014-05-19 02:18
    Ok thank you very much for the feedback it is really appreciated, Does Parallax have a UK based representative with the capability of modifying this internal brownout level value? As i already have 55 boards manufactured my only choices are either modifying that value on this current production or producing a 'sister' board with a charge pump IC to increase the supplied voltage to the 5V point as i only have a 3.7 Lipo battery on the design which is non-changeable due to space restrictions.
  • Jeff MartinJeff Martin Posts: 757
    edited 2014-05-19 11:31
    Hi Dave,

    Sorry, we don't have any distributors that provide that service. The only way to get them would be for us to provide them from our Rocklin, CA headquarters.

    It may be possible for us to reprogram them on your board, but there's chances that won't work depending on our circuit. If you like, we can talk about it to see what is possible and decide how to proceed from there.
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