1 // Copyright (c) 2017, Tobias Mueller tm(at)tm3d.de
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2 // All rights reserved.
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4 // Redistribution and use in source and binary forms, with or without
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5 // modification, are permitted provided that the following conditions are
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8 // * Redistributions of source code must retain the above copyright
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9 // notice, this list of conditions and the following disclaimer.
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10 // * Redistributions in binary form must reproduce the above copyright
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11 // notice, this list of conditions and the following disclaimer in the
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12 // documentation and/or other materials provided with the
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14 // * All advertising materials mentioning features or use of this
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15 // software must display the following acknowledgement: This product
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16 // includes software developed by tm3d.de and its contributors.
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17 // * Neither the name of tm3d.de nor the names of its contributors may
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18 // be used to endorse or promote products derived from this software
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19 // without specific prior written permission.
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21 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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22 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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23 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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24 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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25 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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26 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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27 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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28 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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29 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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30 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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31 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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34 #define F_CPU 8000000UL
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36 #include <util/delay.h>
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37 #include "USI_TWI_Master.h"
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38 #include "SHT2xV2.h"
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40 uint8_t initSHT2x(){
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42 I2c_StartCondition();
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43 I2c_WriteByte(0b10000000);
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44 I2c_WriteByte(0xFE);//Softreset
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45 I2c_StopCondition();
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46 //Default 12 Bit RH 14 Bit T
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50 uint8_t crcmove(uint8_t crc) {
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52 for(bit=8;bit>0;--bit) {
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53 if (crc&0x80) crc=(crc<<1)^ 0x131;
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59 uint8_t calcCRCSHT2x(uint8_t b1, uint8_t b2) {
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64 return crcmove(crc);
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70 uint8_t getSHT2xHumTemp(double *temp,double *hum) {
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72 I2c_StartCondition();
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73 I2c_WriteByte(0b10000000);
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74 I2c_WriteByte(0xF3); //No Hold Temp
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76 I2c_StopCondition();
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78 I2c_StartCondition();
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79 I2c_WriteByte (0b10000001);
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80 uint8_t t1 =I2c_ReadByte(ACK);
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81 uint8_t t2 =I2c_ReadByte(ACK);
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82 uint8_t tc =I2c_ReadByte(NO_ACK);
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83 I2c_StopCondition();
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85 I2c_StartCondition();
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86 I2c_WriteByte(0b10000000);
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87 I2c_WriteByte(0xF5); //No Hold Hum
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89 I2c_StopCondition();
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91 I2c_StartCondition();
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92 I2c_WriteByte (0b10000001);
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93 uint8_t f1 =I2c_ReadByte(ACK);
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94 uint8_t f2 =I2c_ReadByte(ACK);
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95 uint8_t fc =I2c_ReadByte(NO_ACK);
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96 I2c_StopCondition();
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97 if (calcCRCSHT2x(t1,t2)==tc)
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98 *temp=-46.85 + 175.72/65536 *(double)(((uint16_t)t1<<8)|(t2&0xF8));
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100 if (calcCRCSHT2x(f1,f2)==fc)
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101 *hum=-6.0+125.0/65536*(double)(((uint16_t)f1<<8)|(f2&0xF8));
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