实验六 UART通用串行通信模块实验 一、实验目的
掌握异步串口通信模块的原理和用法
二、实验例程 1．例程一
//****************************************************************************** #include
unsigned char i;
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P3SEL = BIT3+BIT4; // P3.4,5 = USCI_A0 TXD/RXD UCA0CTL1 |= UCSWRST; // **Put state machine in reset** 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 UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine** UCA0IE |= UCRXIE; // Enable USCI_A0 RX interrupt __bis_SR_register(LPM3_bits + GIE); // Enter LPM3, interrupts enabled __no_operation(); // For debugger }
// Echo back RXed character, confirm TX buffer is ready first #pragma vector=USCI_A0_VECTOR __interrupt void USCI_A0_ISR(void) {
switch(__even_in_range(UCA0IV,4)) {
case 0:break; // Vector 0 - no interrupt case 2: // Vector 2 - RXIFG
while (!(UCA0IFG&UCTXIFG)); // USCI_A0 TX buffer ready? UCA0TXBUF = UCA0RXBUF; // TX -> RXed character break;
case 4:break; // Vector 4 - TXIFG default: break; } }
2．例程二
//****************************************************************************** #include
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P3SEL |= BIT3+BIT4; // P3.3,4 = USCI_A0 TXD/RXD UCA0CTL1 |= UCSWRST; // **Put state machine in reset** UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 = 9; // 1MHz 115200 (see User's Guide) UCA0BR1 = 0; // 1MHz 115200
UCA0MCTL |= UCBRS_1 + UCBRF_0; // Modulation UCBRSx=1, UCBRFx=0
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine** UCA0IE |= UCRXIE; // Enable USCI_A0 RX interrupt __bis_SR_register(LPM0_bits + GIE); // Enter LPM0, interrupts enabled __no_operation(); // For debugger }
// Echo back RXed character, confirm TX buffer is ready first #pragma vector=USCI_A0_VECTOR __interrupt void USCI_A0_ISR(void) {
switch(__even_in_range(UCA0IV,4)) {
case 0:break; // Vector 0 - no interrupt case 2: // Vector 2 - RXIFG
while (!(UCA0IFG&UCTXIFG)); // USCI_A0 TX buffer ready? UCA0TXBUF = UCA0RXBUF; // TX -> RXed character break;
case 4:break; // Vector 4 - TXIFG default: break; } }
三、实验内容 通过串口实现单片机与计算机之间的数据通讯。 四、实验思考 为什么禁止带电拔插串口线？
实验七 ADC12模数转换实验 一、实验目的
掌握ADC12模数转换模块的原理和用法。 二、实验例程 1．例程一
//****************************************************************************** #include
volatile unsigned int i;
WDTCTL = WDTPW+WDTHOLD; // Stop watchdog timer P6SEL |= 0x01; // Enable A/D channel A0
REFCTL0 &= ~REFMSTR; // Reset REFMSTR to hand over control to // ADC12_A ref control registers ADC12CTL0 = ADC12ON+ADC12SHT02+ADC12REFON+ADC12REF2_5V;
// Turn on ADC12, Sampling time // On Reference Generator and set to // 2.5V
ADC12CTL1 = ADC12SHP; // Use sampling timer
ADC12MCTL0 = ADC12SREF_1; // Vr+=Vref+ and Vr-=AVss for ( i=0; i<0x30; i++); // Delay for reference start-up ADC12CTL0 |= ADC12ENC; // Enable conversions while (1) {
ADC12CTL0 |= ADC12SC; // Start conversion while (!(ADC12IFG & BIT0));
__no_operation(); // SET BREAKPOINT HERE } }
2．例程二
//****************************************************************************** #include
#define Num_of_Results 8
volatile unsigned int A0results[Num_of_Results]; volatile unsigned int A1results[Num_of_Results]; volatile unsigned int A2results[Num_of_Results]; volatile unsigned int A3results[Num_of_Results]; void main(void) {
WDTCTL = WDTPW+WDTHOLD; // Stop watchdog timer P6SEL = 0x0F; // Enable A/D channel inputs
ADC12CTL0 = ADC12ON+ADC12MSC+ADC12SHT0_8; // Turn on ADC12, extend sampling time // to avoid overflow of results
ADC12CTL1 = ADC12SHP+ADC12CONSEQ_3; // Use sampling timer, repeated sequence ADC12MCTL0 = ADC12INCH_0; // ref+=AVcc, channel = A0 ADC12MCTL1 = ADC12INCH_1; // ref+=AVcc, channel = A1 ADC12MCTL2 = ADC12INCH_2; // ref+=AVcc, channel = A2
ADC12MCTL3 = ADC12INCH_3+ADC12EOS; // ref+=AVcc, channel = A3, end seq. ADC12IE = 0x08; // Enable ADC12IFG.3
ADC12CTL0 |= ADC12ENC; // Enable conversions
ADC12CTL0 |= ADC12SC; // Start convn - software trigger __bis_SR_register(LPM0_bits + GIE); // Enter LPM0, Enable interrupts __no_operation(); // For debugger }
#pragma vector=ADC12_VECTOR __interrupt void ADC12ISR (void) {
static unsigned int index = 0;
switch(__even_in_range(ADC12IV,34)) {
case 0: break; // Vector 0: No interrupt case 2: break; // Vector 2: ADC overflow
case 4: break; // Vector 4: ADC timing overflow case 6: break; // Vector 6: ADC12IFG0 case 8: break; // Vector 8: ADC12IFG1 case 10: break; // Vector 10: ADC12IFG2 case 12: // Vector 12: ADC12IFG3
A0results[index] = ADC12MEM0; // Move A0 results, IFG is cleared A1results[index] = ADC12MEM1; // Move A1 results, IFG is cleared A2results[index] = ADC12MEM2; // Move A2 results, IFG is cleared A3results[index] = ADC12MEM3; // Move A3 results, IFG is cleared
index++; // Increment results index, modulo; Set Breakpoint1 here
if (index == 8) {
(index = 0); }
case 14: break; // Vector 14: ADC12IFG4 case 16: break; // Vector 16: ADC12IFG5 case 18: break; // Vector 18: ADC12IFG6 case 20: break; // Vector 20: ADC12IFG7 case 22: break; // Vector 22: ADC12IFG8 case 24: break; // Vector 24: ADC12IFG9 case 26: break; // Vector 26: ADC12IFG10 case 28: break; // Vector 28: ADC12IFG11 case 30: break; // Vector 30: ADC12IFG12 case 32: break; // Vector 32: ADC12IFG13 case 34: break; // Vector 34: ADC12IFG14 default: break; } }
3．例程三
//****************************************************************************** #include
volatile long IntDegF; volatile long IntDegC; void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
REFCTL0 &= ~REFMSTR; // Reset REFMSTR to hand over control to // ADC12_A ref control registers ADC12CTL0 = ADC12SHT0_8 + ADC12REFON + ADC12ON;
// Internal ref = 1.5V ADC12CTL1 = ADC12SHP; // enable sample timer
ADC12MCTL0 = ADC12SREF_1 + ADC12INCH_10; // ADC i/p ch A10 = temp sense i/p ADC12IE = 0x001; // ADC_IFG upon conv result-ADCMEMO __delay_cycles(75); // 75us delay to allow Ref to settle ADC12CTL0 |= ADC12ENC; while(1) {
ADC12CTL0 |= ADC12SC; // Sampling and conversion start __bis_SR_register(LPM4_bits + GIE); // LPM0 with interrupts enabled __no_operation();
// Temperature in Celsius
// ((A10/4096*1500mV) - 680mV)*(1/2.25mV) = (A10/4096*667) - 302 // = (A10 - 1855) * (667 / 4096)
IntDegC = ((temp - 1855) * 667) / 4096; // Temperature in Fahrenheit
// ((A10/4096*1500mV) - 640mV)*(1/1.25mV) = (A10/4096*1200) - 512 // = (A10 - 1748) * (1200 / 4096)
IntDegF = ((temp - 1748) * 1200) / 4096;
__no_operation(); // SET BREAKPOINT HERE } }
#pragma vector=ADC12_VECTOR __interrupt void ADC12ISR (void) {
switch(__even_in_range(ADC12IV,34)) {
case 0: break; // Vector 0: No interrupt case 2: break; // Vector 2: ADC overflow
case 4: break; // Vector 4: ADC timing overflow case 6: // Vector 6: ADC12IFG0
temp = ADC12MEM0; // Move results, IFG is cleared __bic_SR_register_on_exit(LPM4_bits); // Exit active CPU break;
case 8: break; // Vector 8: ADC12IFG1 case 10: break; // Vector 10: ADC12IFG2 case 12: break; // Vector 12: ADC12IFG3 case 14: break; // Vector 14: ADC12IFG4 case 16: break; // Vector 16: ADC12IFG5 case 18: break; // Vector 18: ADC12IFG6 case 20: break; // Vector 20: ADC12IFG7 case 22: break; // Vector 22: ADC12IFG8 case 24: break; // Vector 24: ADC12IFG9 case 26: break; // Vector 26: ADC12IFG10
case 28: break; // Vector 28: ADC12IFG11 case 30: break; // Vector 30: ADC12IFG12 case 32: break; // Vector 32: ADC12IFG13 case 34: break; // Vector 34: ADC12IFG14 default: break; } }
三、实验内容
使用多通道多次转换模式，转换温度传感器、(AVCC – AVSS) / 2、A12、A13四个通道的数据，将数据保存到变量中；把通道数据换算成电压，并与输入电压比较。程序流程图如下所示。
四、实验思考
1．修改转换模式为多通道单次转换模式，了解其转换开始条件。 2．修改转换中断使能，理解中断条件。 3．改变基准源设置，理解转换公式。