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Multiple SPI Slaves

kas.lewis

What is the easiest way to talk to multiple slave devices using and Arduino platform (or TI Energia platform). the issue I am thinking about is having to keep passing the new CS pin the SPI begin function. Any help is much appreciated.

 

Thanks

Kas

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    Kas, you can take this for what it's worth. You see you want a broadcast mode, but you already limited yourself to SPI.

    This is like; Cart before Horse. You should have asked yourself; What do I need?

    • Communications to 'Clients or Slaves'
    • Communications with Broadcast mode.
    • That's is what data do they exchange and is this bi-directional?
    • How much data? Lots or just a Little?
    • etc.

    And then no matter what Communications Hardware or Firmware you have, you have to implement a protocol.

    SPI, I2C have rather short distances it can go, even though I2C has reserved address. they are both on the weak side.

    for CHEAP a few bucks each on ebay i picked up some I2C to CAN bus transceivers. This has broadcast and does about 40 feet on twisted pair.

     

    Dehumidifier messages:

    1 The Temp is xxx

    2 The Humidify is xxx

    3 The Tank is Full

    4 The Tank is not in place

    System messages to the Dehumidifier

    5 Turn ON

    6 Turn OFF

    This is the protocol: bit 0 to bit n Numbers are in HEX

    FF fist two bytes - Start Byte

    01 second two bytes Device # this is the Dehumidifier.

    xx third two bytes Message Code

    xx forth two bytes the Message or Payload

    00 fifth two bytes Stop Byte

     

    Cris

    PS and to anybody that takes a known standard and wants to hack it by adding another "control wire".... I had a real problem I used to make the board myself

    NOW I JUST BUY THEM...LOL

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  • 0

    Kas, you can take this for what it's worth. You see you want a broadcast mode, but you already limited yourself to SPI.

    This is like; Cart before Horse. You should have asked yourself; What do I need?

    • Communications to 'Clients or Slaves'
    • Communications with Broadcast mode.
    • That's is what data do they exchange and is this bi-directional?
    • How much data? Lots or just a Little?
    • etc.

    And then no matter what Communications Hardware or Firmware you have, you have to implement a protocol.

    SPI, I2C have rather short distances it can go, even though I2C has reserved address. they are both on the weak side.

    for CHEAP a few bucks each on ebay i picked up some I2C to CAN bus transceivers. This has broadcast and does about 40 feet on twisted pair.

     

    Dehumidifier messages:

    1 The Temp is xxx

    2 The Humidify is xxx

    3 The Tank is Full

    4 The Tank is not in place

    System messages to the Dehumidifier

    5 Turn ON

    6 Turn OFF

    This is the protocol: bit 0 to bit n Numbers are in HEX

    FF fist two bytes - Start Byte

    01 second two bytes Device # this is the Dehumidifier.

    xx third two bytes Message Code

    xx forth two bytes the Message or Payload

    00 fifth two bytes Stop Byte

     

    Cris

    PS and to anybody that takes a known standard and wants to hack it by adding another "control wire".... I had a real problem I used to make the board myself

    NOW I JUST BUY THEM...LOL

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