測距并通過串口打印的例程
單片機源程序如下:
- #include "User_Uart.h"
- #include "driverlib.h"
- void UCS_Init(void)
- {
- // P1DIR |= BIT0; // ACLK set out to pins
- // P1SEL |= BIT0;
- P2DIR |= BIT2; // SMCLK set out to pins
- P2SEL |= BIT2;
- // P7DIR |= BIT7; // MCLK set out to pins
- // P7SEL |= BIT7;
- P5SEL |= BIT2+BIT3; // Port select XT2
- UCSCTL6 &= ~XT2OFF; // Enable XT2
- UCSCTL3 |= SELREF_2; // FLLref = REFO
- // Since LFXT1 is not used,
- // sourcing FLL with LFXT1 can cause
- // XT1OFFG flag to set
- UCSCTL4 |= SELA_2; // ACLK=REFO,SMCLK=DCO,MCLK=DCO
- // Loop until XT1,XT2 & DCO stabilizes - in this case loop until XT2 settles
- do
- {
- UCSCTL7 &= ~(XT2OFFG + XT1LFOFFG + DCOFFG);
- // Clear XT2,XT1,DCO fault flags
- SFRIFG1 &= ~OFIFG; // Clear fault flags
- }while (SFRIFG1&OFIFG); // Test oscillator fault flag
- UCSCTL6 &= ~XT2DRIVE0; // Decrease XT2 Drive according to
- // expected frequency
- UCSCTL4 |= SELS_5 + SELM_5; // SMCLK=MCLK=XT2
- }
- void Uart_Init(void) // 115200 8N1
- {
- P4SEL |= BIT4+BIT5; // P4.4,5 = USA1 TXD/RXD
- UCA1CTL1 |= UCSWRST; // **Put state machine in reset**
- UCA1CTL1 |= UCSSEL__SMCLK ; // SMCLK
- UCA1BR0 = 34; // 4MHz 115200 (see User's Guide)
- // UCA1BR0 = 輸入的時鐘源/串口通信速率 （取整）
- UCA1BR1 = 0; // 4MHz 115200
- UCA1MCTL = UCBRS_6; // 輸入的時鐘源/串口通信速率的余數(shù)*8
- UCA1CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
- // __bis_SR_register(GIE); // Enter LPM0, interrupts enabled
- }
- #define Trig1(a) if(a==1) P1OUT |= BIT3; else P1OUT &= ~BIT3
- unsigned int cap_new = 0; // 首次捕捉的ta0r值
- unsigned int cap_old = 0; // 二次捕捉的ta0r值
- //char test_num = 10; // 測量次數(shù)
- char cap_N = 0; // 溢出次數(shù)
- char state = 0x00; // zhuangtai
- long cap_data = 0; // 距離值
- //unsigned int dat[test_num]; //通過數(shù)組存10次測量值
- void Hc_sr_Init(void) // 超聲波模塊初始化
- {
- /*
- * P1.2 為echo引腳 捕獲模式
- * P1.2 具有端口中斷的通用數(shù)字I / O ，TA0 CCR1捕獲：CCI1A輸入，比較：Out1輸出 BSL接收輸入
- * P1.3 為Trig 數(shù)字i/o模式
- * P1.3 具有端口中斷的通用數(shù)字I / O ， TA0 CCR2捕獲：CCI2A輸入，比較：Out2輸出
- */
- P1OUT &= ~( BIT2 + BIT3 );
- P1DIR |= BIT3;
- P1SEL |= BIT2;
- /*
- * note：由于選用的是P1.2 根據(jù)端口定義可知，使用的是TA0CCR1，捕獲輸入引腳通過TA0CCTL1寄存器控制，
- *-捕獲值存儲在TA0CCR1中。
- * TASSEL：SNCLK; 分頻：4MHz/8 = 500k；計數(shù)模式：0 ==> 0xFFFF;
- * TA0CCTL1：上升沿捕獲 ；同步捕捉；捕獲模式；CCI1A輸入；
- */
- TA0CTL = TASSEL__SMCLK + ID__8 + MC_2 + TACLR + TAIE;
- TA0CCTL1 = CM_1 + SCS +CAP + CCIE + CCIS_0;
- }
- void Hc_sr_Open(void) //生成一個持續(xù)10us的高電平
- {
- Trig1(1);
- __delay_cycles(40);
- Trig1(0);
- }
- #pragma vector=TIMER0_A1_VECTOR
- __interrupt void TIMER0_A1_ISR(void)
- {
- switch(__even_in_range(TA0IV,14))
- {
- case 0:break; // No interrupt
- case 2:
- state = TA0CCTL1 >> 14;
- TA0CCTL1 &= ~CCIFG;
- if( TA0CCTL1 & CM_1){
- cap_new = TA0CCR1;
- TA0CCTL1 &= ~CM_1;
- TA0CCTL1 |= CM_2;
- }else if ( TA0CCTL1 & CM_2){
- cap_old = TA0CCR1;
- cap_data = ( cap_old - cap_new ) * 0.34;
- UARTprintf("\n\ncap_data: %u mm",cap_data);
- TA0CCTL1 &= ~CM_2;
- TA0CCTL1 |= CM_1;
- }else UARTprintf("\nstate: %x",state); // 判斷CM位捕捉模式
- // UARTprintf("\n yes! ccr1 \nTA0 CCR1: %u TA0R: %u",TA0CCR1,TA0R);
- break; // CCR1 not used
- case 4: break; // CCR2 not used
- case 6: break; // reserved
- case 8: break; // reserved
- case 10: break; // reserved
- case 12: break; // reserved
- case 14:
- TA0CTL &= ~TAIFG;
- if(cap_old < cap_new ){
- cap_N += 1;
- }
- break; // overflow
- default: break;
- }
- }
- void main (void)
- {
- WDT_A_hold(WDT_A_BASE);
- Uart_Init();
- UCS_Init();
- Hc_sr_Init();
- __bis_SR_register(GIE);
- UARTprintf("\nInitialization is complete!");
- while(1)
- {
- Hc_sr_Open();
- __delay_cycles(1000000);
- }
- }
代碼下載:
HCSR04.zip
(655.34 KB, 下載次數(shù): 48)
2022-7-11 19:53 上傳
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