1 | void i2cInit()
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2 | {
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3 | UCB0CTLW0 |= UCSWRST; // put into SW Reset
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4 | UCB0CTLW0 |= UCSSEL_3; // choose SMCLK
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5 | UCB0BRW = 20; // set prescaler = 20 => 400 kHz
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6 | UCB0CTLW0 |= UCMODE_3; // put into I2C Mode
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7 | UCB0CTLW0 |= UCMST; // put into MASTER mode
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8 | UCB0CTLW0 |= UCSYNC; //
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9 | UCB0I2CSA = 0x29; // slave addr = 0x29
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10 |
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11 |
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12 | P1SEL1 &= ~BIT3; // P1.3 = SCL
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13 | P1SEL0 |= BIT3;
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14 |
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15 | P1SEL1 &= ~BIT2; // P1.2 = SDA
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16 | P1SEL0 |= BIT2;
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17 |
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18 | UCB0CTLW0 &= ~UCSWRST; // get out of SW Reset
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19 | }
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20 |
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21 | void i2cReset() {
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22 | UCB0CTLW0 |= UCSWRST; // put into SW Reset
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23 | UCB0CTLW0 &= ~UCSWRST; // get out of SW Reset
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24 | }
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25 |
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26 |
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27 | uint8_t I2C_Read_Byte(uint8_t address, uint8_t *value) {
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28 |
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29 | UCB0CTL1 |= UCTR | UCTXSTT; // transmitter mode + START
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30 | while(UCB0CTL1 & UCTXSTT) ; // wait for START
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31 | while(!((UCB0IFG & UCTXIFG) || (UCB0IFG & UCNACKIFG))); // wait for Tx Buffer
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32 | if(UCB0IFG & UCNACKIFG) // check for NACK
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33 | {
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34 | return 1;
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35 | }
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36 | UCB0TXBUF = address; // write register address
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37 | while(!((UCB0IFG & UCTXIFG) || (UCB0IFG & UCNACKIFG))); // wait for Tx Buffer
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38 | if(UCB0IFG & UCNACKIFG) // check for NACK
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39 | {
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40 | return 2;
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41 | }
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42 | UCB0CTL1 &= ~UCTR; // Receiver Mode
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43 | UCB0CTL1 |= UCTXSTT; // send Repeated Start
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44 | while(UCB0CTL1 & UCTXSTT) ; // wait for START
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45 | UCB0CTL1 |= UCTXSTP; // send STOP
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46 | while (!((UCB0IFG & UCRXIFG))); // wait for RX Buffer
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47 | *value = UCB0RXBUF; // read RX data
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48 | while(UCB0CTL1 & UCTXSTP); // wait for previous transaction to complete
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49 | i2cReset();
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50 |
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51 | return 0;
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52 | }
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53 |
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54 | uint8_t I2C_Read_Bytes(uint8_t address, uint8_t *value, uint8_t length)
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55 | {
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56 | uint8_t i = 0;
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57 |
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58 | UCB0CTL1 |= UCTR | UCTXSTT; // transmitter mode + START
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59 | while(UCB0CTL1 & UCTXSTT) ; // wait for START
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60 | while(!((UCB0IFG & UCTXIFG) || (UCB0IFG & UCNACKIFG))); // wait for Tx Buffer
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61 | if(UCB0IFG & UCNACKIFG) // check for NACK
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62 | {
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63 | return 1;
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64 | }
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65 | UCB0TXBUF = address; // write register address
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66 | while(!((UCB0IFG & UCTXIFG) || (UCB0IFG & UCNACKIFG))); // wait for Tx Buffer
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67 | if(UCB0IFG & UCNACKIFG) // check for NACK
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68 | {
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69 | return 2;
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70 | }
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71 |
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72 | UCB0CTL1 &= ~UCTR; // Receiver Mode
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73 | UCB0CTL1 |= UCTXSTT; // send Start
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74 | while(UCB0CTL1 & UCTXSTT) ; // wait for START
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75 | do
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76 | {
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77 | while(!(UCB0IFG & UCRXIFG)); // wait for Rx Buffer
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78 | value[i] = UCB0RXBUF; // read RX Buffer
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79 | i++;
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80 | }while(i < (length - 1));
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81 |
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82 | while(!(UCB0IFG & UCRXIFG)); // wait for Rx Buffer
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83 |
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84 | UCB0IFG &= ~UCTXIFG;
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85 | UCB0CTL1 |= UCTXSTP;
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86 | value[length - 1] = UCB0RXBUF;
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87 | while(UCB0CTL1 & UCTXSTP); // wait for previous transaction to complete
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88 | i2cReset();
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89 | return 0;
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90 | }
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91 |
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92 | uint8_t I2C_Write_Byte(uint8_t address, uint8_t value)
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93 | {
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94 | UCB0CTL1 |= (UCTR | UCTXSTT);
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95 | while(UCB0CTL1 & UCTXSTT) ; // wait for START
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96 | while(!((UCB0IFG & UCTXIFG) || (UCB0IFG & UCNACKIFG))); // wait for Tx Buffer
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97 | if(UCB0IFG & UCNACKIFG) // check for NACK
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98 | {
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99 | return 1;
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100 | }
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101 |
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102 | UCB0TXBUF = address;
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103 |
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104 | while(!((UCB0IFG & UCTXIFG) || (UCB0IFG & UCNACKIFG))); // wait for Tx Buffer
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105 | if(UCB0IFG & UCNACKIFG) // check for NACK
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106 | {
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107 | return 2;
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108 | }
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109 |
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110 | UCB0TXBUF = value;
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111 |
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112 | while(!((UCB0IFG & UCTXIFG) || (UCB0IFG & UCNACKIFG))); // wait for Tx Buffer
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113 | if(UCB0IFG & UCNACKIFG) // check for NACK
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114 | {
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115 | return 3;
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116 | }
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117 | UCB0CTL1 |= UCTXSTP;
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118 | while(UCB0CTL1 & UCTXSTP); // wait for previous transaction to complete
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119 | i2cReset();
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120 | return 0;
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121 | }
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