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CC1200 SPI MISO

Bob Jiang
Prodigy 190 points
Other Parts Discussed in Thread: SIMPLICITI, CC1200

Hi

I am using the dk-tm4c129x+cc1200 with SimpliciTI.

But now my spi has something wrong.

I use oscilloscope to find that SCLK ，MOSI and SCN has a good  waveform. But MISO did not have any waveform.

What may cause this phenomenon?

Can anyone give me some advice? 

  • 0
    TI__Guru**** 317180 points
    The UserGuide section 3.1.1 say that the MCU has to wait until MISO goes low before starting the communication on the SPI interface. If SO doesn't go low it could be that the xtal hasn't started. Please verify that the xtal is running and the voltage on the R_bias pin is 1.25 V.
  • 0 in reply to TER
    Prodigy 190 points
    Hi

    I have found that dk-tm4c129x contribute to the phenomenon. Now it can work.

    When i debug, the return of SMPL_Link is SMPL_TX_CCA_FAIL. However, when i debug step by step, it return success.

    So i think it is the problem of delay.The mcu of dk_tm4c129x is 120 MHZ. But when i change the delay in the following codes, it run into a Infinite loop.

    for (;;)
    {
    /* Radio must be in RX mode for CCA to happen.
    * Otherwise it will transmit without CCA happening.
    */

    /* Can not use the Mrfi_RxModeOn() function here since it turns on the
    * Rx interrupt, which we don't want in this case.
    */
    mrfiSpiCmdStrobe( SRX );

    Mrfi_DelayUsec(461);
    .
    .
    .
    }
    what should i do to make a successful link?
  • 0 in reply to Bob Jiang
    TI__Mastermind 36395 points
    I agree with your assessment that is delay issue, the SimpliciTI stack has been designed and tested on MSP430 MCU running at 8MHz and now you are running it at 120MHz on a CM4F. I think what is happening is that you are checking for the RX state so fast the the transciever is still transitioning from idle to RX and not ready yet. As Siri says in a different post, please make sure the delay functions in SimpliciTI are actually providing the required delay.

    Regards,
    /TA