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McBSP as SPI on a C6748 / OMAP-L138

Peter Steinberg
Expert 1640 points
Other Parts Discussed in Thread: OMAP-L138, OMAPL138

I'm porting some code from a TMSC6713 to a TMSC6748 / OMAP-L138.

The existing code and hardware uses the McBSP1 to control a peripheral using SPI-Mode Clock stopping (spru580, chapter 9).

 

This is apparently not available in the TMSC6748 (SPRUGJ6C, section 2.5.3.8).

 

Is there a work around for this difference?

 

Thanks,

  Peter Steinberg

  • 0
    TI__Guru*** 125430 points

    Because the device has dedicated SPI peripherals we were able to remove the SPI functionality from the McBSP.

  • 0 in reply to Brad Griffis
    Expert 1640 points

    So the only work-around is to re-layout our board to hook the peripherals up to one of the SPI devices?

  • 0 in reply to Peter Steinberg
    TI__Guru*** 125430 points

    What's connected to the McBSP?  Can it operate in an "always on" mode?  Some data converters for example can operate either with SPI or with an always on clock.  If the external device cannot work in that manner then, yes, the only workaround is to re-layout the board.

  • 0 in reply to Brad Griffis
    Expert 1640 points

    We've got different peripherals on different boards / configurations; some work in always on mode, some do not.

    We've got a rev started to also have the SPI lines available so we can select the appropriate pin configuration and procede.

     

    Thanks,

      Peter

  • 0 in reply to Peter Steinberg
    Prodigy 120 points

    hai

    if i set the OMAPL138 in the below configration mode

    SPI1            McBSP1

    clk <---------CLKX1

    MISO-------->DR1

    MOSI<-------DX1

    CS3<---------GPIO

    why cant i work it like a normal data trasfer from McBSP1 to SPI 1 by the  SPI protocol ? even all those timming diagrams reffered in the data sheets gives an idea to me that its possible

    .@Brad Griffis please make it clear why its not possible as your relpy dosent mention about it.

    with Regards

    Somu Sebastian

  • 0 in reply to somu sebastian
    TI__Guru*** 125430 points

    somu sebastian said:

    why cant i work it like a normal data trasfer from McBSP1 to SPI 1 by the  SPI protocol ? even all those timming diagrams reffered in the data sheets gives an idea to me that its possible

    .@Brad Griffis please make it clear why its not possible as your relpy dosent mention about it.

    Please refer to the TRM Section 26.2.5.3.8 "Stopping Clocks":

    • The SPI™ CLKSTP mode where clocks are stopped between single-element transfers. This mode is
      not supported on this device.