1 | //
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2 | // begin license header
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3 | //
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4 | // This file is part of Pixy CMUcam5 or "Pixy" for short
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5 | //
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6 | // All Pixy source code is provided under the terms of the
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7 | // GNU General Public License v2 (http://www.gnu.org/licenses/gpl-2.0.html).
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8 | // Those wishing to use Pixy source code, software and/or
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9 | // technologies under different licensing terms should contact us at
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10 | // cmucam@cs.cmu.edu. Such licensing terms are available for
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11 | // all portions of the Pixy codebase presented here.
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12 | //
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13 | // end license header
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14 | //
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15 | // This file is for defining the SPI-related classes. It's called Pixy.h instead
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16 | // of Pixy_SPI.h because it's the default/recommended communication method
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17 | // with Arduino. This class assumes you are using the ICSP connector to talk to
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18 | // Pixy from your Arduino. For more information go to:
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19 | //
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20 | //http://cmucam.org/projects/cmucam5/wiki/Hooking_up_Pixy_to_a_Microcontroller_(like_an_Arduino)
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21 | //
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22 |
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23 | #ifndef PIXY_H
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24 | #define PIXY_H
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25 |
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26 | #include "TPixy.h"
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27 | #include "SPI.h"
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28 |
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29 |
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30 | #define PIXY_SYNC_BYTE 0x5a
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31 | #define PIXY_SYNC_BYTE_DATA 0x5b
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32 | #define PIXY_BUF_SIZE 16
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33 |
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34 | template <class BufType> struct CircularQ
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35 | {
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36 | CircularQ()
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37 | {
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38 | len = 0;
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39 | writeIndex = 0;
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40 | readIndex = 0;
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41 | }
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42 |
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43 | bool read(BufType *c)
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44 | {
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45 | if (len)
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46 | {
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47 | *c = buf[readIndex++];
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48 | len--;
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49 | if (readIndex==PIXY_BUF_SIZE)
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50 | readIndex = 0;
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51 | return true;
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52 | }
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53 | else
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54 | return false;
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55 | }
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56 |
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57 | uint8_t freeLen()
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58 | {
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59 | return PIXY_BUF_SIZE-len;
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60 | }
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61 |
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62 | bool write(BufType c)
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63 | {
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64 | if (freeLen()==0)
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65 | return false;
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66 |
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67 | buf[writeIndex++] = c;
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68 | len++;
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69 | if (writeIndex==PIXY_BUF_SIZE)
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70 | writeIndex = 0;
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71 | return true;
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72 | }
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73 |
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74 | BufType buf[PIXY_BUF_SIZE];
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75 | uint8_t len;
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76 | uint8_t writeIndex;
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77 | uint8_t readIndex;
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78 | };
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79 |
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80 | class LinkSPI
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81 | {
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82 | public:
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83 | void init()
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84 | {
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85 | SPI.begin();
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86 |
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87 | #ifdef ARDUINO_ARCH_SAMD
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88 | // DUE clock divider //
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89 | SPI.setClockDivider(84);
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90 | #else
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91 | // Default clock divider //
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92 | SPI.setClockDivider(SPI_CLOCK_DIV16);
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93 | #endif
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94 | }
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95 |
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96 | uint16_t getWord()
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97 | {
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98 | // ordering is different (big endian) because Pixy is sending 16 bits through SPI
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99 | // instead of 2 bytes in a 16-bit word as with I2C
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100 | uint16_t w;
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101 |
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102 | if (inQ.read(&w))
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103 | return w;
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104 |
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105 | return getWordHw();
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106 | }
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107 |
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108 | uint8_t getByte()
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109 | {
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110 | return SPI.transfer(0x00);
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111 | }
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112 |
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113 | int8_t send(uint8_t *data, uint8_t len)
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114 | {
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115 | int i;
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116 |
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117 | // check to see if we have enough space in our circular queue
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118 | if (outQ.freeLen()<len)
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119 | return -1;
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120 |
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121 | for (i=0; i<len; i++)
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122 | outQ.write(data[i]);
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123 | flushSend();
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124 | return len;
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125 | }
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126 |
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127 | void setArg(uint16_t arg)
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128 | {
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129 | }
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130 |
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131 | private:
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132 | uint16_t getWordHw()
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133 | {
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134 | // ordering is different (big endian) because Pixy is sending 16 bits through SPI
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135 | // instead of 2 bytes in a 16-bit word as with I2C
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136 | uint16_t w;
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137 | uint8_t c, cout = 0;
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138 |
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139 | if (outQ.read(&cout))
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140 | w = SPI.transfer(PIXY_SYNC_BYTE_DATA);
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141 | else
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142 | w = SPI.transfer(PIXY_SYNC_BYTE);
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143 |
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144 | w <<= 8;
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145 | c = SPI.transfer(cout);
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146 | w |= c;
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147 |
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148 | return w;
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149 | }
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150 |
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151 | void flushSend()
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152 | {
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153 | uint16_t w;
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154 | while(outQ.len)
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155 | {
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156 | w = getWordHw();
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157 | inQ.write(w);
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158 | }
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159 | }
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160 |
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161 | // we need a little circular queues for both directions
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162 | CircularQ<uint8_t> outQ;
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163 | CircularQ<uint16_t> inQ;
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164 | };
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165 |
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166 |
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167 | typedef TPixy<LinkSPI> Pixy;
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168 |
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169 | #endif
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