/* * Basic ASCII UART example for MSP430FR2633 EVM * Demonstrates both transmit and receive handlers * Runs at 9600 or 115200 baud */ #include #include #include #include //****************************************************************************** // PROGRAM DEFINES //****************************************************************************** #define LED_OUT P1OUT #define LED_DIR P1DIR #define LED_PIN BIT0 #define SMCLK_115200 0 #define SMCLK_9600 1 // SELECT THE BAUD RATE #define UART_MODE SMCLK_9600 //#define UART_MODE SMCLK_115200 //****************************************************************************** // GLOBAL PROGRAM VARIABLES //****************************************************************************** unsigned char RXDataBuffer[64]; unsigned char TXDataBuffer[64]; unsigned char* pTXBuffer = &TXDataBuffer[0]; unsigned char* pRXBuffer = &RXDataBuffer[0]; unsigned int bytesToSend; unsigned int bytesReceived; bool msg_received = false; bool uart_busy = false; //****************************************************************************** // UART Initialization //****************************************************************************** void initUART() { // Configure USCI_A0 for UART mode UCA0CTLW0 |= UCSWRST; // Put eUSCI in reset #if UART_MODE == SMCLK_115200 UCA0CTLW0 |= UCSSEL__SMCLK; // CLK = SMCLK // Baud Rate Setting // Use Table 21-5 UCA0BRW = 8; UCA0MCTLW |= UCOS16 | UCBRF_10 | 0xF700; //0xF700 is UCBRSx = 0xF7 #elif UART_MODE == SMCLK_9600 UCA0CTLW0 |= UCSSEL__SMCLK; // CLK = SMCLK // Baud Rate Setting // Use Table 21-5 UCA0BRW = 104; UCA0MCTLW |= UCOS16 | UCBRF_2 | 0xD600; //0xD600 is UCBRSx = 0xD6 #else # error "Please specify baud rate to 115200 or 9600" #endif UCA0CTLW0 &= ~UCSWRST; // Initialize eUSCI UCA0IE |= UCRXIE; // Enable USCI_A0 RX interrupt } //****************************************************************************** // GPIO Initialization //****************************************************************************** void initGPIO() { // Set the two pins that drive LEDs as outputs P1DIR = BIT6 | BIT7; P1OUT = 0x00; // Configure GPIO as USCI_A0 UART PINS P1SEL0 |= BIT4 | BIT5; // Not using PORT2 so set as outputs and drive low P2DIR = 0xFF; P2OUT = 0x00; // Not using PORT3 so set as outputs and drive low P3DIR = 0xFF; P3OUT = 0x00; // Disable the GPIO power-on default high-impedance mode to activate // previously configured port settings PM5CTL0 &= ~LOCKLPM5; } //****************************************************************************** // Clock Initialization //****************************************************************************** void initClockTo16MHz() { // Configure one FRAM waitstate as required by the device datasheet for MCLK // operation beyond 8MHz _before_ configuring the clock system. FRCTL0 = FRCTLPW | NWAITS_1; __bis_SR_register(SCG0); // disable FLL CSCTL3 |= SELREF__REFOCLK; // Set REFO as FLL reference source CSCTL0 = 0; // clear DCO and MOD registers CSCTL1 &= ~(DCORSEL_7); // Clear DCO frequency select bits first CSCTL1 |= DCORSEL_5; // Set DCO = 16MHz CSCTL2 = FLLD_0 + 487; // set to fDCOCLKDIV = (FLLN + 1)*(fFLLREFCLK/n) // = (487 + 1)*(32.768 kHz/1) // = 16 MHz __delay_cycles(3); __bic_SR_register(SCG0); // enable FLL while(CSCTL7 & (FLLUNLOCK0 | FLLUNLOCK1)); // FLL locked CSCTL4 = SELMS__DCOCLKDIV | SELA__REFOCLK; } //****************************************************************************** // Transmits data out UART //****************************************************************************** void TransmitData(unsigned char* string, unsigned int length) { // Turn on TX LED (P1.6) to show we are transmitting P1OUT |= BIT6; // Wait here in case transmission already in progress while(uart_busy == true); uart_busy = true; // Show the UART is busy pTXBuffer = string; // Set pointer to the transmit buffer bytesToSend = length; // Setup how many bytes to send UCA0IE |= UCTXIE; // Enable USCI_A0 TX interrupt // From here the UART will automatically transmit all the bytes in the string // while the CPU remains in LPM0. } int main(void) { WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer initGPIO(); initClockTo16MHz(); initUART(); __bis_SR_register(GIE); // Example use of timer to send periodic message to PC // Skip this if you are sending other messages // Configure timer to periodically transmit string TA0CCTL0 |= CCIE; // TACCR0 interrupt enabled TA0CTL |= TASSEL__SMCLK | MC__CONTINUOUS | ID__8; // SMCLK, continuous mode while (1) { // Enter LPM0 and wait for interrupt to wake the CPU __bis_SR_register(LPM0_bits | GIE); // Ok we are awake so // Check if message was received and send an acknowledgment if(msg_received == true) { TransmitData("Thanks!\r\n", 9); msg_received = false; } } } //****************************************************************************** // USCI_A0 ISR HANDLER //****************************************************************************** #pragma vector=USCI_A0_VECTOR __interrupt void USCI_A0_ISR(void) { switch(__even_in_range(UCA0IV,USCI_UART_UCTXCPTIFG)) { case USCI_NONE: break; case USCI_UART_UCRXIFG: P1OUT |= BIT7; // Turn on RX LED UCA0IFG &=~ UCRXIFG; // Clear interrupt *pRXBuffer = UCA0RXBUF; // Clear buffer if (UCA0RXBUF == '\r') // This works because my terminal app sends CR only (\r). If yours sends CR + LF change this to '\n' msg_received = true; P1OUT &= (~BIT7); // Turn off RX LED __bic_SR_register_on_exit(LPM0_bits); // Exit LPM0 on reti break; case USCI_UART_UCTXIFG: UCA0TXBUF = *pTXBuffer++; if(--bytesToSend == 0) { UCA0IE &= ~UCTXIE; // Disable USCI_A0 TX interrupt after last byte of string has been transmitted. P1OUT &= (~BIT6); // Turn off TX LED uart_busy = false; __bis_SR_register_on_exit(LPM0_bits); // Exit LPM0 on reti } break; case USCI_UART_UCSTTIFG: break; case USCI_UART_UCTXCPTIFG: break; } } // Set our test message as const so it will be placed in FRAM, not RAM const uint8_t HelloMsg[] = "Hello MSP430 World - Have a great day!\r\n"; //****************************************************************************** // TIMER0_A0 ISR HANDLER - Automatically transmits message to PC terminal //****************************************************************************** #pragma vector = TIMER0_A0_VECTOR __interrupt void Timer_A (void) { static int count = 40; uint8_t length; if(--count == 0) { count = 40; // # of bytes to send is one less than the string length. // Compiler added '0' to end of our string and we don't want to send it. // TO ENABLE SENDING STATIC MESSAGE, SET #if 1 // TO ENABLE SENDING DYNAMIC MESSAGE, SET #1 0 #if 0 // Send static message TransmitData((uint8_t*) HelloMsg, sizeof(HelloMsg)-1); #else // Send dynamic message - in this case the current value of timer //Use sprintf() function to automatically convert TA0R into ASCII length = sprintf((char*)TXDataBuffer, "%d\r\n", TA0R); TransmitData(TXDataBuffer, length); #endif } }