root / branches / autonomous_recharging / code / projects / autonomous_recharging / archs / I2c test / i2c.c @ 383
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1 | 355 | bneuman | /* I2C.c
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2 | |||
3 | I2C Communication
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4 | |||
5 | Problem switching into slave mode. So never run as a slave otherwise you will never be able
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6 | to speak again (unless a master tells you to).
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7 | |||
8 | */
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9 | |||
10 | #include "i2c.h" |
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11 | /*
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12 | int main(void) {
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13 | i2c_test();
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14 | }
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15 | */
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16 | //Call this to start I2C up
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17 | void i2c_init(void) { |
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18 | //Start off in slave mode so you can catch any data that comes your way
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19 | //USI_TWI_Slave_Initialise(0x02);
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20 | |||
21 | //Can't ever be a slave otherwise you will die. Stay as master and never give it up.
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22 | USI_TWI_Master_Initialise(); |
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23 | |||
24 | } |
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25 | |||
26 | |||
27 | //Call this to send a packet. *data is a char array of data_size. Make sure you put in data_size or we won't send
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28 | //everything.
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29 | //Note, mainboard is addr = 0x01.
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30 | void i2c_putpacket(char addr, char *data, char data_size) { |
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31 | //The packet that we will transmit over I2C
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32 | unsigned char packet[data_size + 1]; |
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33 | |||
34 | //First byte is the destination address + R/W (R = 1, W = 0)
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35 | packet[0] = addr << 1; //Shift the address over 1 bit, LSB is 0 which means write |
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36 | |||
37 | //Put data into packet
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38 | for (int i = 0; i < data_size; i++) { |
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39 | packet[i+1] = data[i];
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40 | } |
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41 | |||
42 | 383 | bneuman | PORTB&=~_BV(PB4); |
43 | |||
44 | 355 | bneuman | //Send packet. Will open line, transmit, and close line.
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45 | USI_TWI_Start_Transceiver_With_Data(packet, (data_size + 1));
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46 | 383 | bneuman | |
47 | PORTB&=~_BV(PB5); |
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48 | 355 | bneuman | |
49 | } |
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50 | |||
51 | int i2c_getpacket(char *c) { |
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52 | if (USI_TWI_Data_In_Receive_Buffer()) {
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53 | *c = USI_TWI_Receive_Byte(); |
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54 | return 0; |
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55 | } else{
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56 | return -1; |
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57 | |||
58 | } |
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59 | } |
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60 | |||
61 | void delay_ms(int ms) |
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62 | { |
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63 | for(; ms > 15; ms-=15) |
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64 | _delay_ms(15);
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65 | _delay_ms(ms); |
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66 | } |
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67 | |||
68 | |||
69 | // Note this will fail. You need to fix the switch from slave -> master before it will succeed.
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70 | void i2c_test(void) { |
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71 | char datatx[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}; |
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72 | char datarx;
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73 | |||
74 | DDRA = _BV(PA3) | _BV(PA4) | _BV(PA5) | _BV(PA6) | _BV(PA7); |
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75 | PORTA = 0;
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76 | PORTA |= _BV(PA3); |
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77 | |||
78 | //delay_ms(1000);
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79 | |||
80 | sei(); |
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81 | i2c_init(); |
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82 | |||
83 | while(1) { |
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84 | delay_ms(1000);
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85 | i2c_putpacket(0x01, datatx, 26); |
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86 | } |
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87 | |||
88 | /*
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89 | while(1) {
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90 | i2c_getpacket(&datarx);
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91 | |||
92 | switch (datarx) {
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93 | case 'a':
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94 | PORTA |= _BV(PA4);
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95 | break;
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96 | case 'b':
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97 | PORTA |= _BV(PA5);
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98 | break;
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99 | case 'c':
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100 | PORTA |= _BV(PA6);
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101 | break;
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102 | case 'd':
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103 | PORTA |= _BV(PA7);
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104 | break;
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105 | }
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106 | |||
107 | if (datarx == 'd')
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108 | break;
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109 | }
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110 | |||
111 | PORTA = 0;
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112 | |||
113 | |||
114 | //PORTA |= _BV(PA5);
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115 | delay_ms(1000);
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116 | i2c_putpacket(0x01, datatx, 26);
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117 | */
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118 | } |