1 | #include "msp430g2553.h"
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2 |
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3 | unsigned char *pRXData;
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4 | unsigned char *pTXData;
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5 | unsigned char bufferTX[16] = {"Hello World!\0"};
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6 | unsigned char bufferRX[16] = {" "};
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7 | unsigned char TxByteCtr;
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8 | unsigned char RxByteCtr;
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9 |
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10 |
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11 | void main(void)
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12 | {
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13 | WDTCTL = WDTPW + WDTHOLD; // Stop WDT
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14 | P1DIR |= BIT0; // P1.0 output
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15 | P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
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16 | P1SEL2|= BIT6 + BIT7; // Assign I2C pins to USCI_B0
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17 |
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18 | UCB0CTL1 |= UCSWRST; // Enable SW reset
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19 | UCB0CTL0 = UCMODE_3 + UCSYNC; // I2C Slave, synchronous mode
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20 | UCB0I2COA = 0x48; // Own Address is 048h
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21 | UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
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22 | UCB0I2CIE |= UCSTTIE; // Enable STT interrupt
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23 | IE2 |= UCB0TXIE; // Enable TX interrupt
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24 | // TXData = 0xff; // Used to hold TX data
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25 | IE2 |= UCB0RXIE; // Enable RX interrupt //
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26 |
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27 | while (1)
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28 | {
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29 | pTXData = (unsigned char *)bufferTX;
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30 | pRXData = (unsigned char *)bufferRX;
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31 | TxByteCtr = 0;
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32 | RxByteCtr = 0;
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33 | __bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
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34 | __no_operation(); ///////
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35 | }
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36 | }
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37 |
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38 | //#define UCSCLLOW (0x40) /* SCL low */
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39 | //#define UCGC (0x20) /* General Call address received Flag */
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40 | //#define UCBBUSY (0x10) /* Bus Busy Flag */
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41 | //#define UCNACKIFG (0x08) /* NAK Condition interrupt Flag */
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42 | //#define UCSTPIFG (0x04) /* STOP Condition interrupt Flag */
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43 | //#define UCSTTIFG (0x02) /* START Condition interrupt Flag */
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44 | //#define UCALIFG (0x01) /* Arbitration Lost interrupt Flag */
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45 |
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46 | volatile unsigned char lastCharTx = 0;
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47 | volatile unsigned char lastCharRx = 0;
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48 |
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49 |
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50 |
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51 | int testWhileRx = 0;
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52 | int testWhileTx = 0;
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53 | unsigned char state = 0;
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54 | int endReached = 0;
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55 | // USCI_B0 Data ISR
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56 | #pragma vector = USCIAB0TX_VECTOR // I2C DataVector = UART_TX_Vector
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57 | __interrupt void USCIA0_TX_USCIB0_I2C_DATA_ISR(void)
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58 | {
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59 | if (state & UCTR)
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60 | {
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61 | while((IFG2 & UCB0TXIFG) == 0){testWhileTx++;}
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62 | if (endReached == 0)
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63 | {
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64 | lastCharTx = *pTXData;
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65 | if (lastCharTx == 0)
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66 | {
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67 | endReached = 1;
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68 | }
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69 | }
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70 | else
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71 | {
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72 | lastCharTx = 0;
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73 | }
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74 | UCB0TXBUF = lastCharTx;
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75 | pTXData++;
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76 | TxByteCtr++;
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77 | if (TxByteCtr >= 0x10)
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78 | {
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79 | pTXData = (unsigned char *)bufferTX;
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80 | pRXData = (unsigned char *)bufferRX;
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81 | TxByteCtr = 0;
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82 | RxByteCtr = 0;
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83 | endReached = 0;
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84 | __bic_SR_register_on_exit(CPUOFF); // Exit LPM0
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85 | }
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86 | }
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87 | else
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88 | {
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89 | while((IFG2 & UCB0RXIFG) == 0){testWhileRx++;}
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90 | lastCharRx = UCB0RXBUF;
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91 | *pRXData = lastCharRx;
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92 | pRXData++;
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93 | RxByteCtr++;
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94 |
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95 | if(RxByteCtr >= 0x10 || (lastCharRx == 0 && RxByteCtr > 1))
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96 | {
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97 | pTXData = (unsigned char *)bufferTX;
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98 | pRXData = (unsigned char *)bufferRX;
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99 | TxByteCtr = 0;
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100 | RxByteCtr = 0;
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101 | endReached = 0;
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102 | __bic_SR_register_on_exit(CPUOFF); // Exit LPM0
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103 | }
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104 | }
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105 | }
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106 |
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107 | // USCI_B0 State ISR
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108 | #pragma vector = USCIAB0RX_VECTOR // I2C StateVector = UART_RX_Vector
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109 | __interrupt void USCIA0_RX_USCIB0_I2C_STATE_ISR(void)
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110 | {
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111 | while (UCB0CTL1 & UCTXSTP); // Ensure stop condition got sent
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112 | UCB0STAT &= ~UCSTTIFG; // Clear start condition int flag
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113 | state = UCB0CTL1 & UCTR;
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114 | }
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