TMDSCNCD28335: F28335 SPI Conmmunication between Two F28335 Device

Hi team,

I help my customer to ask a question.

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I am trying to get started with the SPI function on F28335. Right now, I am using two TMDSCNCD28335 control cards with docking stations. As I am trying to start, I am planning to use board 1 as the master device in SPI, and use board 2 as the slave device. Device 1 will send the time data with the second unit to device 2. Device 2 will only send the dummy data of 0xF to device 1. For my dissertation project, I am using the ADC interrupt triggered by EPWMSOCA instead of the SPI interrupts. I modified the demo code from the control suite to achieve this task. But it looks the data received by device 1/2 are all random values instead of the value I loaded into transmitter buffers. Here is my partial code for SPI:

DEVICE #1

void InitSpiFifoMaster()
{
	/*Initializa SPI Slave Mode without FIFO*/
	SpiaRegs.SPICCR.bit.SPISWRESET = 0; 		// Reset SPI
	
	SpiaRegs.SPICCR.bit.SPICHAR = 0xF;			// Set SPI charater length to be 16-bit (0xF)
	SpiaRegs.SPICTL.bit.MASTER_SLAVE = 1;		// Master->1, Slave->0
	SpiaRegs.SPICTL.bit.TALK = 1;				// Transmit Enable. Set as 0 will disable TX for next word by set output line HIGH
	SpiaRegs.SPIBRR = 0x0063;           		// Set baud rate: 40MHz/(0x63+0x1)=40MHz/100=400bps
	SpiaRegs.SPIPRI.bit.FREE = 1;				// Enable Free Run, continure SPI operation no matter the suspend occurred
	/*Set SPI FIFO Regs*/
	SpiaRegs.SPIFFTX.bit.SPIRST = 1;			// SPI Reset, SPI FIFO can resume transmit/receive
	SpiaRegs.SPIFFTX.bit.SPIFFENA = 1;			// SPI FIFO Enable
	SpiaRegs.SPIFFTX.bit.TXFIFO = 1;			// TX FIFO Release from reset mode
	SpiaRegs.SPIFFTX.bit.TXFFINTCLR = 1;		// Clear TXFIFO Interrupt (W1C: Write on to clear)
	SpiaRegs.SPIFFTX.bit.TXFFIL = 0x00;			// Set TX FIFO Interrupt Level to be 0
	SpiaRegs.SPIFFRX.bit.RXFIFORESET = 1;		// Release Receive FIFO from reset mode
	SpiaRegs.SPIFFRX.bit.RXFFINTCLR = 1;		// Clear SPI FIFO RXFFINTCLR flag (W1C: write one to clear)
	SpiaRegs.SPIFFRX.bit.RXFFIL = 0x0;			// Set RX FIFO Interrupt Level to be 0
	SpiaRegs.SPIFFCT.bit.TXDLY = 0x00;			// FIFO transmit delay to be zero

	SpiaRegs.SPICCR.bit.SPISWRESET=1;  			// Release SPI from reset mode
}

void SpiTxDat(Uint16 tx)
{
	/*MASTER SEND TIME TO SLAVE*/
	GpioDataRegs.GPACLEAR.bit.GPIO19 = 1;
	SpiaRegs.SPITXBUF = tx;						// Load data to SPI Output Buffer
	while(SpiaRegs.SPIFFRX.bit.RXFFST != 1);	// Wait until data is received
	DataSpiRx = SpiaRegs.SPIRXBUF;				// Read received data
	GpioDataRegs.GPASET.bit.GPIO19 = 1;
}

DEVICE #2

void InitSpiFifoSlave()
{
	/*Initializa SPI Slave Mode without FIFO*/
	SpiaRegs.SPICCR.bit.SPISWRESET = 0; 		// Reset SPI
	
	SpiaRegs.SPICCR.bit.SPICHAR = 0xF;			// Set SPI charater length to be 16-bit (0xF)
	SpiaRegs.SPICTL.bit.MASTER_SLAVE = 0;		// Master->1, Slave->0
	SpiaRegs.SPICTL.bit.TALK = 1;				// Transmit Enable. Set as 0 will disable TX for next word by set output line HIGH
	SpiaRegs.SPIBRR = 0x0063;           		// Set baud rate: 40MHz/(0x63+0x1)=40MHz/100=400bps
	SpiaRegs.SPIPRI.bit.FREE = 1;				// Enable Free Run, continure SPI operation no matter the suspend occurred
	/*Set SPI FIFO Regs*/
	SpiaRegs.SPIFFTX.bit.SPIRST = 1;			// SPI Reset, SPI FIFO can resume transmit/receive
	SpiaRegs.SPIFFTX.bit.SPIFFENA = 1;			// SPI FIFO Enable
	SpiaRegs.SPIFFTX.bit.TXFIFO = 1;			// TX FIFO Release from reset mode
	SpiaRegs.SPIFFTX.bit.TXFFINTCLR = 1;		// Clear TXFIFO Interrupt (W1C: Write on to clear)
	SpiaRegs.SPIFFTX.bit.TXFFIL = 0x00;			// Set TX FIFO Interrupt Level to be 0
	SpiaRegs.SPIFFRX.bit.RXFIFORESET = 1;		// Release Receive FIFO from reset mode
	SpiaRegs.SPIFFRX.bit.RXFFINTCLR = 1;		// Clear SPI FIFO RXFFINTCLR flag (W1C: write one to clear)
	SpiaRegs.SPIFFRX.bit.RXFFIL = 0x0;			// Set RX FIFO Interrupt Level to be 0
	SpiaRegs.SPIFFCT.bit.TXDLY = 0x00;			// FIFO transmit delay to be zero

	SpiaRegs.SPICCR.bit.SPISWRESET=1;  			// Release SPI from reset mode
}

void SpiRxDat(void)
{
	SpiaRegs.SPITXBUF = 0xF;
	while(SpiaRegs.SPIFFRX.bit.RXFFST != 1);	// Wait until data is received
	DataSpiRx = SpiaRegs.SPIRXBUF;
}

I am not sure which setup is wrong in my code.

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Thank you very much for your help.

Best regards,