usci_a_uart_ex3_autoBaudrateDetectionTX.c

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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#include "driverlib.h"
 
//******************************************************************************
//******************************************************************************
#define BAUD_RATE                               9600
#define TRANSMIT_DATA_COUNT                     0x03
#define USCI_A_UART_MULTIPROCESSOR_MODE_ADDRESS        0xAA
 
uint8_t receivedData = 0x00, transmitData = 0x00;
uint8_t transmitDataCount = TRANSMIT_DATA_COUNT;
 
void main (void)
{
    //Stop WDT
    WDT_A_hold(WDT_A_BASE);
 
    //P3.4,5 = USCI_A0 TXD/RXD
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P3,
        GPIO_PIN4 + GPIO_PIN5
        );
 
    //Initialize USCI UART module
    //Baudrate = 9600, clock freq = 1.048MHz
    //UCBRx = 6, UCBRFx = 13, UCBRSx = 0, UCOS16 = 1
    USCI_A_UART_initParam param = {0};
    param.selectClockSource = USCI_A_UART_CLOCKSOURCE_SMCLK;
    param.clockPrescalar = 6;
    param.firstModReg = 13;
    param.secondModReg = 0;
    param.parity = USCI_A_UART_NO_PARITY;
    param.msborLsbFirst = USCI_A_UART_LSB_FIRST;
    param.numberofStopBits = USCI_A_UART_ONE_STOP_BIT;
    param.uartMode = USCI_A_UART_AUTOMATIC_BAUDRATE_DETECTION_MODE;
    param.overSampling = USCI_A_UART_OVERSAMPLING_BAUDRATE_GENERATION;
    if (STATUS_FAIL == USCI_A_UART_init(USCI_A0_BASE, &param)){
        return;
    }
 
    //Enable UART module for operation
    USCI_A_UART_enable(USCI_A0_BASE);
 
    //Transmit Break
    USCI_A_UART_transmitBreak(USCI_A0_BASE);
 
    //Wait till ,odule is ready to transmit again
    while (!USCI_A_UART_getInterruptStatus(USCI_A0_BASE,
               USCI_A_UART_TRANSMIT_INTERRUPT_FLAG)) ;
 
    //Transmit data
    USCI_A_UART_transmitData(USCI_A0_BASE,
        transmitData++);
    transmitDataCount--;
 
    //Enable Receive Interrupt
    USCI_A_UART_clearInterrupt(USCI_A0_BASE,
        USCI_A_UART_RECEIVE_INTERRUPT);
    USCI_A_UART_enableInterrupt(USCI_A0_BASE,
        USCI_A_UART_RECEIVE_INTERRUPT);
 
    //Enter LPM3, interrupts enabled
    __bis_SR_register(LPM3_bits + GIE);
    __no_operation();
}
 
//******************************************************************************
//
//This is the USCI_A0 interrupt vector service routine.
//
//******************************************************************************
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_A0_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(USCI_A0_VECTOR)))
#endif
void USCI_A0_ISR (void)
{
    switch (__even_in_range(UCA0IV,4)){
        //Vector 2 - RXIFG
        case 2:
 
            //USCI_A0 TX buffer ready?
            while (!USCI_A_UART_getInterruptStatus(USCI_A0_BASE,
                       USCI_A_UART_TRANSMIT_INTERRUPT_FLAG)) ;
 
            //Receive the data
            receivedData = USCI_A_UART_receiveData(USCI_A0_BASE);
 
            if (transmitDataCount){
                //Send data
                USCI_A_UART_transmitData(USCI_A0_BASE,
                    transmitData++);
                transmitDataCount--;
            } else   {
                //Send Break
                USCI_A_UART_transmitBreak(USCI_A0_BASE);
                transmitDataCount = TRANSMIT_DATA_COUNT - 1;
 
                //Wait till module is ready to transmit next data
                while (!USCI_A_UART_getInterruptStatus(USCI_A0_BASE,
                           USCI_A_UART_TRANSMIT_INTERRUPT_FLAG)) ;
 
                //Transmit next data
                USCI_A_UART_transmitData(USCI_A0_BASE,
                    transmitData++);
            }
 
            break;
        default: break;
    }
}