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AMS AS3935 Lightning Detector Datasheet Error? (SOLVED)

Discussion in 'Microcontrollers' started by jpanhalt, Jul 13, 2017.

  1. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I have been playing with the AMS AS3935 Lightning Detector and comparing it with results from a homemade receiver and ADC/oscilloscope.

    Came across this in the data sheet (page 12):
    upload_2017-7-13_15-25-51.png
    Source: http://media.digikey.com/pdf/Data Sheets/Austriamicrosystems PDFs/AS3935.pdf

    AMS does not define MMSByte, but by common usage, an MMSByte is between the LSB and MSB, i.e., the first "M" means "middle." However, the datasheet is suspicious, as it implies the MMSB is the highest byte, not a middle byte. Moreover, the order of the registers and the fact that it is only a 5-bit byte seem to suggest that it is the most significant byte.

    Has anyone come across the use of MMSB to mean "most, most significant" instead of "middle, most/more significant?"


    AMS has not published an errata for that chip that I can find. FWIW, there is a well-known error in the I2C address.

    I wrote a routine to read and display those three registers, but it may be a few days before I get to test it.

    John
     
  2. ci139

    ci139 Active Member

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    the typos of various type - also "typos" on circuit diagrams - are quite regular on datasheets (the last one i recall noticing was using V instead of mV or the way around)
     
  3. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    SOLVED

    Response from Ms. Kumin at AMS:
    “The energy value is a 20 bit value which is divided into a LSB (lowest 8bit in Reg 0x04), and MSB (medium 8 bit in Reg 0x05) and a MMSB (upper 4 bit value, lower nibble in Reg 0x06). MMSB is not between LSB and MSB”.

    Comment: New definition for MSB. And apparently, AMS also considers the lower nibble of a byte to have 5 bits, not just 4 bits. No error in the datasheet.;)

    John
     

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