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SPI communication between TM4C123H6PMI's

Victor Azevedo
Intellectual 725 points

Good afternoon TI community, i've looking for a good way to send data between  Tiva's TM4C123H6PMI, and i found that i can use the SSI module to do it. I still havent's connected any because i only tried the spi_master example and since any of the tiva have the CLK, FSS, Rx and Tx, i dont know if i can just put like:

Clk-Clk

Fss-Fss

Tx-Rx

Rx-Tx

I would like to exchange information between SSI module. Can i use SSI0-SSI0? do i have to make SSI0-SSI1, any special way. 

  • 0
    TI__Guru**** 244400 points

    Hello Victor,

    If the SSI modules are on two different TIVA's then any combination is possible. However do note that on TM4C123 SSI, the TX pin is TX for both Slave and Master. So the above configuration should be valid.

    On the TM4C part where you have a slave, enable the Slave function when configuring using SSIConfigSetExpClk

    Also please note that the Slave CLK on the serial interface cannot work more than 1/12 of the System Clock. So do configure the Master Serial Clock rate accordingly.

    Regards

    Amit

  • 0 in reply to Amit Ashara
    Guru 47900 points

    Amit Ashara said:
    note that on TM4C123 SSI, the TX pin is TX for both Slave and Master.

    Hi Amit,

    You're the clear expert here - these parts.  Yet - having used SPI for years - often in very pro/hi-rel applications - we've most always routed:

    Master.......Slave

    MOSI ....... MOSI

    MISO.........MISO

    SCLK........SCLK

    SFSS........SFSS

    Thus - should not "both" TX and RX (as illustrated here) be commonly connected?

    And you've, (singled out) "TM4C123."  Does the SSI pin treatment of that MCU differ from all others?

    Merci...

  • 0 in reply to cb1
    Intellectual 725 points

    I think it should be MOSI-MISO and MISO-MOSI because, i have to program each microcontroller and that i know what i send from one will be the other return and same in the oposite direction.

    Yes i still haven't found an example converting an ADC read to SPI byte write/send, something i would like. I have checked that SPI works with ASCII and hexadecimal i guess, but i dont know how to convert

  • 0 in reply to Victor Azevedo
    TI__Guru**** 244400 points

    Hello cb1

    Key word "TM4C123" as on TM4C129 the TX and RX are not the same PA2 and PA3 muxed pins.

    Hello Victor,

    ", i have to program each microcontroller and that i know what i send from one will be the other return and same in the oposite direction."

    The Slave cannot start a transaction by itself, I hope that you have taken the same into account. There is no example of ADC conversion and then SPI Byte Write. However you can take the spi and adc example code and in the Interrupt Handler of ADC call the SSIDataPut after reading it from the ADC Data Buffer. The configuration of SPI can be done before the ADC Configuration.

    Regards

    Amit