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USCI

USCI. 彈性極佳的新型通用串列介面 U niversal S erial C ommunication I nterface. USCI. USCI_A. UART ( 支援 IrDA/LIN) 或 SPI 波特率 (Baud-rate) 產生器及自動波特率偵測 雙 Buffer TX/RX. USCI_B. 支援高達 400kHz 的 I2C master 或 slave 模式或 SPI Bit clock 產生器 雙 Buffer TX/RX. Lab ( 主程式 ). #include "msp430x54x.h"

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USCI

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  1. USCI 彈性極佳的新型通用串列介面Universal Serial Communication Interface

  2. USCI USCI_A • UART (支援IrDA/LIN) 或SPI • 波特率(Baud-rate)產生器及自動波特率偵測 • 雙Buffer TX/RX USCI_B • 支援高達400kHz的I2C master或slave 模式或 SPI • Bit clock產生器 • 雙Buffer TX/RX

  3. Lab (主程式) #include "msp430x54x.h" void main(void) { WDTCTL = WDTPW + WDTHOLD; // Stop WDT P5SEL = BIT6+BIT7; // P5.7 5.6 = USCI_A1 TXD/RXD UCA1CTL1 |= UCSWRST; // **Put state machine in reset** UCA1CTL1 |= UCSSEL_1; // CLK = ACLK UCA1BR0 = 0x03; // 32kHz/9600=3.41 (see User's Guide) UCA1BR1 = 0x00; // Baud rate的設定可參考user’s guide UCA1MCTL = UCBRS_3+UCBRF_0; // Modulation UCBRSx=3, UCBRFx=0 UCA1CTL1 &= ~UCSWRST; // **Initialize USCI state machine** UCA1IE |= UCRXIE; // Enable USCI_A1 RX interrupt __bis_SR_register(LPM3_bits + GIE); // Enter LPM3, interrupts enabled } 在電子通訊領域，鮑率（Baud rate）即調制速率，指的是信號被調制以後在單位時間內的變化，即單位時間內載波參數變化的次數。它是對符號傳輸速率的一種度量，1鮑即指每秒傳輸1個符號。 單位「鮑」本身就已經是代表每秒的調制數，以「鮑每秒」（Baud per second）為單位是一種常見的錯誤。

  4. Lab (中斷服務程式) // Echo back RXed character, confirm TX buffer is ready first #pragma vector=USCI_A1_VECTOR __interrupt void USCI_A1_ISR(void) { switch(__even_in_range(UCA1IV,4)) { case 0:break; case 2: // Vector 2 - RXIFG while (!(UCA1IFG&UCTXIFG)); // USCI_A1 TX buffer ready? UCA1TXBUF = UCA1RXBUF; // TX -> RXed character break; case 4:break; default: break; } }

  5. USCI

  6. USCI-模式選擇

  7. USCI-初始化

  8. USCI-傳送致能

  9. USCI-傳送格式

  10. USCI-中斷

  11. USCI-中斷

  12. USCI-中斷

  13. USCI-鮑率計算

  14. USCI-鮑率計算(低頻)

  15. USCI-鮑率計算(高頻)

  16. 課堂實驗 • 因器材不足無法看到結果,所以直接判斷程式修改 • LAB1:將範例波特率由9600改為4800 • LAB2:將程式修改頻率為10mhz 波特率為115200 其中初始CLK “ACLK = REFO = 32768Hz, MCLK = SMCLK = default DCO/2 = 1048576Hz” • LAB3:將範例由”傳出所接收到的資料”改為傳出字元’E’

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