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TMS320F28335: SCI B Communication issue on the TMS320F28335 eZdsp board

Munaf Shaik
Prodigy 190 points

Part Number: TMS320F28335

Hi,

I am using TMS320F28335 eZdsp board. Trying to transmit and receive data on the SCI B.

I have configured GPIO9 and GPIO11 for SCI B communication and reading/writing the data through terminal. I have used Pin 3 and 5 of J12 on the eZdsp board, for transmit and receive.

When i did GPIO9 and GPIO11 configuration i have no signal on the SCI B, i.e Pin 3 and Pin 5 of J12.

Then after reading through different forums i have done the below sequence of strange configurations,

Step1: Configured GPIO18 and GPIO19 as SCI B peripheral 

Step2: Configured GPIO9 and GPIO11 as SCI B peripheral

Step3: Configured GPIO18 and GPIO19 as SCI B peripheral

With above configurations i am able to transmit data from the Pin 3 of J12. Really not sure what makes it to transmit data with this strange GPIO configurations.

Now my problem is, SCI B Receive is not happening even with this strange configuration. I am able to transmit the data from terminal which i have verified, but controller not able to receive it. 

I have experimented same on multiple F28335 eZdsp boards but could not get SCI B working.

Can any one help me in setting up SCI B communication on F28335 eZdsp board.?

Thanks in advance.

  • 0
    TI__Mastermind 42195 points

    Munaf,

    I have not heard of this workaround you are talking about, where did you find it? Can you show it to me?

    I don't guarantee the accuracy of the following code, however I expect the setup code for GPIO9 and 11 to look something like the following.

    EALLOW;

    //
    // Enable internal pull-up for the selected pins
    // Pull-ups can be enabled or disabled disabled by the user.  
    // This will enable the pullups for the specified pins.
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO8 = 0;  // Enable pull-up for GPIO8 (SCIRXDB)
    GpioCtrlRegs.GPAPUD.bit.GPIO9 = 0;	 // Enable pull-up for GPIO9 (SCITXDB)

    //
    // Set qualification for selected pins to asynch only
    // Inputs are synchronized to SYSCLKOUT by default.  
    // This will select asynch (no qualification) for the selected pins.
    //
    GpioCtrlRegs.GPAQSEL2.bit.GPIO8 = 3;  // Asynch input GPIO8 (SCIRXDB)
    
    //
    // Configure SCI-B pins using GPIO regs
    // This specifies which of the possible GPIO pins will be SCI functional
    // pins.
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO8 = 2;   // Configure GPIO8 to SCIRXDB 
    GpioCtrlRegs.GPAMUX2.bit.GPIO9 = 2;   // Configure GPIO9 to SCITXDB 

EDIS;


    Regards,
    Cody

  • 0 in reply to Cody Watkins
    Prodigy 190 points

    Hi Cody,

    Thank you for your reply.

    You can see the workaround mentioned in the following link

    e2e.ti.com/.../2048117

    Yes,I had configured GPIO9 and GPIO11 in the same way mentioned in your reply post.

    Thank you.

  • 0 in reply to Munaf Shaik
    Prodigy 190 points

    Any suggestions or workaround to bring up SCI B?

  • 0 in reply to Munaf Shaik
    TI__Mastermind 42195 points
    Munaf,
    You shouldn't need to setup 18/19 to get 9/11 to work... do you have a oscilloscope that you could use to scope GPIO9 and GPIO11, can you see anything?

    Regards,
    Cody