DMA trigger is not happened

Each DMA transfer requires a trigger, and you're simply missing to trigger the first one. You can either start by transferring the first byte manually (UCA0TXBUF) and set the DMA start address to the second position, or (dirty) clear and set UCTXIFG in UCA0IFG to generate a fake interrupt.

After the first byte, the TX interrupts will trigger each subsequent transfer until everything is transmitted.

Some general issues: you didn't enable DMAIE for your DMA channel even though you have an ISR, and if you use SMCLK instead of ACLK for your application, you'll have to adapt the baudrate dividers.

Thanks Michael,

I tried the two procedures which you explained but i am not getting trigger. Can you guide me where i made mistake.

#include <msp430.h>

static char String1[] = { "Hello World" };

int main(void)

{  

WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog

  P2SEL = BIT4+BIT5;                        // P4.4,5 = UART1 TXD/RXD
  UCA0CTL1 |= UCSWRST;                     // **Initialize USCI state machine**
  // configure USCI_A1 UART
  UCA0CTL1 = UCSSEL__SMCLK;                      // SMCLK
  UCA0BR0 = 0x03;                           // 32768Hz 9600 32k/9600=3.41
  UCA0BR1 = 0x0;
  UCA0MCTL = UCBRS_3+UCBRF_0;               // Modulation UCBRSx = 3
  UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**

  DMA0CTL &= ~DMAEN;
  DMA0CTL = DMADT_4;
  DMA0CTL = DMASRCINCR_3;
  DMA0CTL = DMASBDB;

 DMA0SZ = sizeof String1;                // Block size
  __data16_write_addr((unsigned short) &DMA0SA,(unsigned long) (String1+1));
                                            // Source block address
  __data16_write_addr((unsigned short) &DMA0DA,(unsigned long) &UCA0TXBUF);
                                            // Destination single address

  DMA0CTL &= ~(DMAIFG);
   // configure DMA0
  DMACTL0 = DMA0TSEL_17;                    
  DMA0CTL |= DMAEN;

/*To make fake interrupt*/

/*  UCA0IFG &= ~(UCTXIFG);
  UCA0IFG |= UCTXIFG;*/

/*To transfer first byte manually*/

UCA0TXBUF = 0x48;

}

please guide me wheteher i made correctly to trigger DMA.

Thanks in advance

Please don't change your configuration at random. Your DMA0CTL accesses overwrite every previous configuration.

    DMA0SZ = sizeof String1-2;
    DMA0CTL = DMADT_0 + DMASRCINCR_3 + DMASBDB + DMAIE;
    DMA0CTL |= DMAEN;

    __bis_SR_register(GIE);

    UCA0TXBUF = *String1;

    while(1);

You also deleted the while(1); statement. If you still want to use interrupts, please return to your previous code sample, otherwise remove my GIE statement and DMAIE. I just tried it, and it works just fine with both variants.

Thanks Michael,

But still this way is not works i have done the code as follows

#include <msp430.h>

static char String1[] = { "HelloWorld" };

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

 P2SEL = BIT4+BIT5;                        // P4.4,5 = UART1 TXD/RXD
  UCA0CTL1 |= UCSWRST;                     // **Initialize USCI state machine**
  // configure USCI_A1 UART
  UCA0CTL1 |= UCSSEL_3;                      // SMCLK
  UCA0BR0 |= 0x03;                           // 32768Hz 9600 32k/9600=3.41
  UCA0BR1 |= 0x0;
  UCA0MCTL |= UCBRS_3+UCBRF_0;               // Modulation UCBRSx = 3
  UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**

DMA0CTL &= ~DMAEN;
  DMA0CTL |= DMADT_0;
  DMA0CTL |= DMASRCINCR_3;
  DMA0CTL |= DMASBDB;
 
  DMA0SZ = sizeof String1-2;                // Block size
  __data16_write_addr((unsigned short) &DMA0SA,(unsigned long) String1);
                                            // Source block address
  __data16_write_addr((unsigned short) &DMA0DA,(unsigned long) &UCA0TXBUF);
                                            // Destination single address

DMA0CTL &= ~(DMAIFG);

DMACTL0 |= DMA0TSEL_17; 

DMA0CTL |= DMAEN;

UCA0TXBUF = *String1;

while(1);

}

but the fake interrupt method is works fine Thanks a lot...

IF UCTXIFG toggling works then writing to UCA0TXBUF should do the job, too. The code you posted works fine after changing the DMA0SA to (String1+1).

Hi Michael,

Thanks for your reply

can you please explain me how to trigger the DMA when receive through UART. I have done the code as follows

  
                DMA1CTL &= ~DMAEN; 
                 
                DMACTL0 = DMA1TSEL_16;    //DMA1TSEL_16 
  
                DMA1CTL |= DMADT_0; 
                
                DMA1CTL |= DMADSTINCR_3;   
                   
                DMA1CTL |= DMASBDB;    
               
                DMA1SZ = buf_ptr->szBuf;    
              
                DMA1SA = (uint16_t)&uartRegister0->rxbuf;
                     
                DMA1DA =(uint16_t)buf_ptr->txrxbuf_ptr; //buffer to read values
                        
                DMA1CTL = DMAIE;  
                  
                DMA1CTL &= ~DMAIFG;
                       
                DMA1CTL |= DMAEN;

while checking in debugger UCOE bit is set, based on that i think the trigger for DMA1 is not occured.

I tested in loopback mode concept, whichever sends through DMA0  its received through DMA1, the rxbuff is updated with the values sent, but the destination address also not increments.

can you guide me how to enable trigger for receive

Thanks in advance