Вот что я в итоге сделал. Оно работает!
struct {
#ifndef USE_DMA
volatile uint8_t rx_head ;
#endif
volatile uint8_t rx_tail ;
uint8_t rx_buffer[128];
} uart = { 0,0};
void UART_Init(void)
{
#ifndef USE_DMA
uart.rx_head = 0;
#endif
uart.rx_tail = 0;
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
PMAPPWD = 0x02D52; // Get write-access to port mapping regs
P1MAP5 = PM_UCA0RXD; // Map UCA0RXD output to P1.5
P1MAP6 = PM_UCA0TXD; // Map UCA0TXD output to P1.6
PMAPPWD = 0; // Lock port mapping registers
P1DIR |= BIT6; // Set P1.6 as TX output
P1SEL |= BIT5 + BIT6; // Select P1.5 & P1.6 to UART function
UCA0CTL1 = UCSWRST; // **Put state machine in reset**
#ifdef UART_9600
UCA0CTL1 |= UCSSEL_1; // CLK = ACLK
UCA0BR0 = 0x03; // 32kHz/9600=3.41 (see User's Guide)
UCA0BR1 = 0x00; //
UCA0MCTL = UCBRS_3+UCBRF_0; // Modulation UCBRSx=3, UCBRFx=0
#elif defined(UART_9600_SMCLK)
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 = 0xE2; // 12MHz/12500
UCA0BR1 = 0x04; //
UCA0MCTL = UCBRS_2+UCBRF_0; // Modulation UCBRSx=3, UCBRFx=0
#elif defined(UART_115200)
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 = 104; // 12MHz/115200
UCA0BR1 = 0; //
UCA0MCTL = UCBRS_1 + UCBRF_0; // Modulation UCBRSx=1, UCBRFx=0
#else
#error Please select one of the supported baudrates.
#endif
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
#ifdef USE_DMA
memset(uart.rx_buffer,0,sizeof(uart.rx_buffer));
DMACTL0 = DMA0TSEL_16; // USCIA0 RX trigger
DMA0SAL = (uint16_t) &UCA0RXBUF; // Source address
DMA0DAL = (uint16_t) uart.rx_buffer; // Destination address
DMA0SZ = sizeof(uart.rx_buffer); // Block size. this counts down to 0, then reloads.
DMA0CTL = DMADSTINCR_3 + DMASBDB + DMADT_4 + DMALEVEL;
DMA0CTL |= DMAEN;
#else
UCA0IE |= UCRXIE; // Enable USCI_A0 RX interrupt
#endif
}
int UART_GetChar(void)
{
#ifdef USE_DMA
if (DMA0SZ + uart.rx_tail != sizeof(uart.rx_buffer))
#else
if ( uart.rx_head != uart.rx_tail)
#endif
{
int c;
c = uart.rx_buffer[uart.rx_tail];
uint8_t next = uart.rx_tail + 1;
if (next >= sizeof(uart.rx_buffer)) next = 0;
uart.rx_tail = next;
return c;
}
return -1;
}