RTOS/LAUNCHXL-CC1350: CC1350 SPI Slave mode not working reliably

Tool/software: TI-RTOS

Greetings:

I have a CC1350 SPI slave that I cannot get to work correctly. I have attempted slaving it to both a BeagleBone Black and a Teensy (via Arduino), but I cannot shakedown the root cause of these errors. I get about a 5:1 error:success radio sending a 3-byte frame {0x7f,0x00,0xff}. It appears that the values in the receive buffer are correct, but not in the proper sequence. This suggests to me some sort of timing issue. I have attempted tests on all modes, with the latest test using mode 3 in a nearly identical configuration to that depicted in the documentation for SPICC26XXDMA.h. Furthermore, I have attempted various configurations for the pin config values to no success. The results are similar regardless of whether or not I use the wakeup feature.

Excerpt from <Board>.h

/* SPI Board */
#define CC1350_LAUNCHXL_SPI0_MISO             IOID_8          /* RF1.20 */
#define CC1350_LAUNCHXL_SPI0_MOSI             IOID_9          /* RF1.18 */
#define CC1350_LAUNCHXL_SPI0_CLK              IOID_10         /* RF1.16 */
#define CC1350_LAUNCHXL_SPI0_CSN              IOID_11

Excerpt from <Board>.c

    CC1350_LAUNCHXL_SPI0_MOSI | PIN_INPUT_EN | PIN_PULLDOWN,                                            /* SPI master out - slave in */
    CC1350_LAUNCHXL_SPI0_MISO | PIN_GPIO_OUTPUT_EN | PIN_GPIO_LOW | PIN_PUSHPULL,                                            /* SPI master in - slave out */
    CC1350_LAUNCHXL_SPI0_CLK | PIN_INPUT_EN | PIN_PULLDOWN,                                             /* SPI clock */
    CC1350_LAUNCHXL_SPI0_CSN | PIN_INPUT_EN | PIN_PULLDOWN,                                             /* SPI CS */

SPI Task

Void spiTaskFunc( UArg arg0, UArg arg1 )
{
    SPI_Handle handle;
    SPI_Params params;
    SPI_Transaction transaction;
    uint8_t rxBuf[3] = {0};                  // Receive and transmit buffer

    // Init SPI and specify non-default parameters
    SPI_Params_init(&params);
    params.transferTimeout = SPI_WAIT_FOREVER;
    params.bitRate             = 1000000;
    params.frameFormat         = SPI_POL1_PHA1;
    params.mode                = SPI_SLAVE;
//    params.transferMode        = SPI_MODE_CALLBACK;
    //    params.transferCallbackFxn = transferCallback
    params.transferMode        = SPI_MODE_BLOCKING;
    params.dataSize = 8;

    // Configure the transaction
    transaction.count = 3;
    transaction.txBuf = NULL;
    transaction.rxBuf = rxBuf;
    // Open the SPI and initiate the first transfer
    handle = SPI_open(CC1350_LAUNCHXL_SPI0, &params);

    //    SPI_control(handle, SPICC26XXDMA_RETURN_PARTIAL_ENABLE, NULL);
    PIN_Id pin = CC1350_LAUNCHXL_SPI0_CSN;
    SPI_control(handle, SPICC26XXDMA_CMD_SET_CSN_PIN, &pin);

    uint32_t successcounter = 0;
    uint32_t errorcounter = 0;
    while(1)
    {
        memset( rxBuf, 0, 3 );

        SPI_transfer(handle, &transaction);

        if( rxBuf[0] == 0x7f && rxBuf[1] == 0x00 && rxBuf[2] == 0xff )
        {
            successcounter += 1;
        }
        else
        {
            errorcounter += 1;
        }
    }
}

Arduino code

#include <SPI.h>  // include the SPI library:

const int slaveSelectPin = 10;

SPISettings settingsA(1000000, MSBFIRST, SPI_MODE3);

void setup() {

  Serial.begin(9600);

  // set the slaveSelectPin as an output:
  pinMode (slaveSelectPin, OUTPUT);
  // initialize SPI:
  SPI.begin();
 
}

//char data[3] = {'H','i','\0'};
//char data[3] = { 0x88, 0x88, 0x00};
uint8_t data[3] = { 0x7F, 0x00, 0xFF};
char temp;

void loop() {

  SPI.beginTransaction(settingsA);

  //Wakeup CC1350
  digitalWrite (slaveSelectPin, LOW);
  digitalWrite (slaveSelectPin, HIGH);

  //Start SPI transfer
  digitalWrite (slaveSelectPin, LOW);
  SPI.transfer( (uint8_t) data[0] );
  digitalWrite (slaveSelectPin, HIGH);
 
  digitalWrite (slaveSelectPin, LOW);
  SPI.transfer( (uint8_t) data[1] );
  digitalWrite (slaveSelectPin, HIGH);
 
  digitalWrite (slaveSelectPin, LOW);
  SPI.transfer( (uint8_t) data[2] );
  digitalWrite (slaveSelectPin, HIGH);

//  Serial.print("Received: ");
//  temp = (char) SPI.transfer( 0 );
//  Serial.print(temp);
//  temp = (char) SPI.transfer( 0 );
//  Serial.print(temp);
//  temp = (char) SPI.transfer( 0 );
//  Serial.println(temp);
 
  SPI.endTransaction();

//  digitalWrite (slaveSelectPin, HIGH);

  Serial.print("Sent " );
  Serial.println( (char *) data );

  delay(1);
}