SX28 Datasheet Quick Read Through

Found the answer to why the instruction set I read threw me off the one time.
A superset of these instructions are available in the SASM
assembler of the SX-Key IDE, and supported by the SX
Key User’s Manual. Both are available for free download

This 'Native' instruction set is more to my liking.

43 instructions. Very PIC like.

Manual is like a breath of fresh air compared to Microchip datasheet.

This SX datasheet was either written BY Parallax or with their co-operation.

Will post link to it.


  • Here's the link.

    This is a FINE piece of writing.It is done by Parallax.

    Yet it within the constraints of working with a set piece of hardware.

    It is copyrighted 2008.This is most excellent!

  • Here's another little 'nugget of gold' in here.The internal oscillator.
    The internal RC mode uses an internal oscillator, so the
    device does not need any external components. At
    4 MHz, the internal oscillator provides typically +/-8%
    accuracy over the allowed temperature range. The internal
    clock frequency can be divided down to provide one of
    eight lower-frequency choices by selecting the desired
    value in the FUSE Word register. The frequency range is
    from 31.25 KHz to 4 MHz. The default operating
    frequency of the internal RC oscillator may not be 4
    MHz. This is due to the fact that the SX device requires
    trimming to obtain 4 MHz operation. The parts shipped
    out of the factory are not trimmed. The device relies on
    the programming tool provided by the third party vendors
    to support trimming.
    Figure 9-

    What that means to us is you can run it at 31.25 khz.That is k hertz not mega.

    That means you can write simple 32 count delay loops.Instead of loop upon loop to slow down a fast chip.

    Another tidbit is it says 'Fuse' about some of the registers.That is early terminology of micro's.

    Replaced by 'configuration'.

  • Do you talk to yourself at the bus stop, too?

  • May I resume here?

    Looking at the Configuration section of manual.

    There is no Config line like with PIC's.

    You do the configuration with the programmer.SX Blitz or SX Key.

    A little strange but I can live with it.
  • microcontrolleruser,

    PIC programmers not only write to the program into program memory, but also write to data to the EEPROM and burn in the Configuration Bits.

  • Thanks Genetix

    Yes.Different.That's for sure.

    The SX Key also runs at 20mhz while it programs.That's kind of odd.

    Then when it is debugging it does the same.

    Guess it was a tradeoff to get the debugger built into the programmer at the time.
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