MSP430F5438A: Sending SPI message from master to slave

Hello,

I added the line:
__delay_cycles (100);

at the end of the master init.

When I ran the code, I succeeded to send one byte.
But then the while hanged.
The receive interrupt was not called:

#pragma vector=USCI_B0_VECTOR
__interrupt void USCI_B0_ISR(void)
{
switch(__even_in_range(UCB0IV,4))
{
case 0:
break; // Vector 0 - no interrupt
case 2: // Vector 2 - RXIFG
break;
case 4:
break; // Vector 4 - TXIFG
default:
break;
}
}

Can you help ?

Thank you,
Z.V

Hello Z.V,

P3.7 should connect to P3.1 and P5.4 to P3.2. Also initialize UCB1 (master) before UCB0 (slave) so that the master starts the SPI CLK in time for the slave to recognize it upon starting.

Regards,
Ryan

Hi Bryan, All,

I connected the SIMO, SOMI lines but I still have the same problem.
In the following code, UCB0 is master and UCB1 is slave. 

I want to send 100 bytes from master to slave.
Only the first byte is sent and then the MCU hangs in the line:

while (!(UCB0IFG & UCTXIFG));

The ISR:  USCI_B1_ISR is not called. 

Can you help ?

Best regards,
Z.V

---

#include <msp430f5438a.h>
int Recv=0;

/*************************************************************************************
	mcu_to_a2d_init
	Description:	Initialize SPI channel from FPGA to MCU. MCU is slave.
					Channel: UCB0
*************************************************************************************/
int master_init (void)
{
	P3SEL |= BIT1;                       		// P3.1 UCB0SIMO (Slave in, master out – USCI_B0 SPI mode)
	P3SEL |= BIT2; 	  	  	  	  	  	  		// P3.2 UCB0SOMI (Slave out, master in – USCI_B0 SPI mode)
	P3SEL |= BIT3;                            	// P3.3 UCB0CLK  (Clock in\out)

	UCB0CTL1 |= UCSWRST;                      	// Put state machine in reset**
	UCB0CTL0 |= UCMST+UCSYNC+UCCKPL+UCMSB;    	// 3-pin, 8-bit SPI master, Clock polarity high, MSB
	UCB0CTL1 |= UCSSEL_2;                     	// SMCLK
	UCB0BR0 = 0x02;                           	// /2
	UCB0BR1 = 0;                              	//
	UCB0CTL0 = 0;                             	// No modulation
	UCB0CTL1 &= ~UCSWRST;                     	// **Initialize USCI state machine**

	return 0;
}

/*************************************************************************************
	fpga_to_mcu_init
	Description:	Initialize SPI channel from MCU to A2D. MCU is master.
					Channel: UCB1
*************************************************************************************/
int slave_init (void)
{
	P3SEL |= BIT7;                       		// P3.7 UCB1SIMO (Slave in, master out – USCI_B1 SPI mode)
	P5SEL |= BIT4; 	  	  	  	  	  	  	  	// P5.4 UCB1SOMI (Slave out, master in – USCI_B1 SPI mode)
	P5SEL |= BIT5;                            	// P5.5 UCB1CLK  (Clock in\out)

	UCB1CTL1 |= UCSWRST;                      	// **Put state machine in reset**
	UCB1CTL0 |= UCSYNC+UCCKPL+UCMSB;          	// 3-pin, 8-bit SPI slave,	                                            // Clock polarity high, MSB
	UCB1CTL1 &= ~UCSWRST;                     	// **Initialize USCI state machine**
	UCB1IE |= UCRXIE;                         	// Enable USCI_B1 RX interrupt

	return 0;
}

/*************************************************************************************/
int main (void)
{
	WDTCTL = WDTPW + WDTHOLD;           // Stop watchdog timer

	master_init ();
	slave_init ();
	 __delay_cycles(1000);                       // Wait for slave to initialize

	__bis_SR_register(GIE);				// Enable interrupts

	spi_send_msg ();

	return 0;
}

/*************************************************************************************/
int spi_send_msg (void)
{
	unsigned char MST_Data;
	int i;

	for (i=0;i<100;i++)
	{
		while (!(UCB0IFG & UCTXIFG));
		UCB0TXBUF = 5;
	}

	return 0;
}

/*************************************************************************************/
#pragma vector=USCI_B1_VECTOR
__interrupt void USCI_B1_ISR(void)
{
  char MST_Data;

  switch(__even_in_range(UCB1IV,4))
  {
    case 0:
    	break;                          // Vector 0 - no interrupt
    case 2:                             // Vector 2 - RXIFG
    	MST_Data = UCB1RXBUF;
    	Recv++;
    	break;
    case 4:
    	break;                          // Vector 4 - TXIFG
    default:
    	break;
  }
}

/*************************************************************************************/
#pragma vector=USCI_B0_VECTOR
__interrupt void USCI_B0_ISR(void)
{
  char MST_Data;

  switch(__even_in_range(UCB0IV,4))
  {
    case 0:
    	break;                          // Vector 0 - no interrupt
    case 2:                             // Vector 2 - RXIFG
    	MST_Data = UCB0RXBUF;
    	break;
    case 4:
    	break;                          // Vector 4 - TXIFG
    default:
    	break;
  }
}

Hi Ryan,

Thank you very much !

Now it works.

Best regards,

Z.V