/*********************************************************************************
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* Copyright: (C) 2018 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: sht20.c
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* Description: This file is temperature and relative humidity sensor SHT20 code
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*
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* Version: 1.0.0(2018/10/14)
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* Author: Guo Wenxue <guowenxue@gmail.com>
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* ChangeLog: 1, Release initial version on "2018/10/14 12:13:26"
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*
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* Pin connection:
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*
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* vcc --- #Pin17 ( 3.3v )
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* GND --- #Pin20 ( GND )
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* SDA --- #Pin02 ( SDA )
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* SCL --- #Pin03 ( SCL )
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*
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* /boot/config.txt:
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*
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* dtparam=i2c_arm=on
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*
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********************************************************************************/
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#include <stdio.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/ioctl.h>
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#include <linux/types.h>
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#include <sys/stat.h>
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#include <linux/i2c-dev.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <string.h>
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#include <stdint.h>
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#include <time.h>
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#include <errno.h>
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#include <string.h>
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#define SOFTRESET 0xFE
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#define TRIGGER_TEMPERATURE_NO_HOLD 0xF3
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#define TRIGGER_HUMIDITY_NO_HOLD 0xF5
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//#define I2C_API_IOCTL /* Use I2C userspace driver ioctl API */
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#define I2C_API_RDWR /* Use I2C userspace driver read/write API */
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static inline void msleep(unsigned long ms);
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static inline void dump_buf(const char *prompt, uint8_t *buf, int size);
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int sht2x_init(void);
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int sht2x_get_serialnumber(int fd, uint8_t *serialnumber, int size);
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int sht2x_get_temp_humidity(int fd, float *temp, float *rh);
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int main(int argc, char **argv)
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{
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int fd;
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float temp;
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float rh;
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uint8_t serialnumber[8];
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fd = sht2x_init();
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if(fd < 0)
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{
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printf("SHT2x initialize failure\n");
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return 1;
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}
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if( sht2x_get_serialnumber(fd, serialnumber, 8) < 0)
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{
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printf("SHT2x get serial number failure\n");
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return 3;
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}
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if( sht2x_get_temp_humidity(fd, &temp, &rh) < 0 )
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{
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printf("SHT2x get get temperature and relative humidity failure\n");
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return 3;
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}
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printf("Temperature=%lf ℃ relative humidity=%lf%\n", temp, rh);
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close(fd);
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}
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static inline void msleep(unsigned long ms)
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{
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struct timespec cSleep;
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unsigned long ulTmp;
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cSleep.tv_sec = ms / 1000;
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if (cSleep.tv_sec == 0)
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{
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ulTmp = ms * 10000;
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cSleep.tv_nsec = ulTmp * 100;
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}
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else
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{
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cSleep.tv_nsec = 0;
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}
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nanosleep(&cSleep, 0);
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}
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static inline void dump_buf(const char *prompt, uint8_t *buf, int size)
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{
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int i;
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if( !buf )
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{
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return ;
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}
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if( prompt )
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{
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printf("%s ", prompt);
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}
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for(i=0; i<size; i++)
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{
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printf("%02x ", buf[i]);
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}
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printf("\n");
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return ;
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}
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#ifdef I2C_API_RDWR /* Use I2C userspace driver read/write API */
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int sht2x_softreset(int fd)
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{
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uint8_t buf[4];
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if( fd<0 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/* software reset SHT2x */
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memset(buf, 0, sizeof(buf));
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buf[0] = SOFTRESET;
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write(fd, buf, 1);
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msleep(50);
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return 0;
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}
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int sht2x_init(void)
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{
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int fd;
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if( (fd=open("/dev/i2c-1", O_RDWR)) < 0)
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{
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printf("i2c device open failed: %s\n", strerror(errno));
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return -1;
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}
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/* set I2C mode and SHT2x slave address */
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ioctl(fd, I2C_TENBIT, 0); /* Not 10-bit but 7-bit mode */
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ioctl(fd, I2C_SLAVE, 0x40); /* set SHT2x slava address 0x40*/
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if( sht2x_softreset(fd) < 0 )
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{
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printf("SHT2x softreset failure\n");
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return -2;
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}
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return fd;
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}
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int sht2x_get_temp_humidity(int fd, float *temp, float *rh)
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{
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uint8_t buf[4];
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if( fd<0 || !temp || !rh )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/* send trigger temperature measure command and read the data */
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memset(buf, 0, sizeof(buf));
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buf[0]=TRIGGER_TEMPERATURE_NO_HOLD;
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write(fd, buf, 1);
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msleep(85); /* datasheet: typ=66, max=85 */
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memset(buf, 0, sizeof(buf));
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read(fd, buf, 3);
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dump_buf("Temperature sample data: ", buf, 3);
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*temp = 175.72 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 46.85;
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/* send trigger humidity measure command and read the data */
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memset(buf, 0, sizeof(buf));
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buf[0] = TRIGGER_HUMIDITY_NO_HOLD;
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write(fd, buf, 1);
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msleep(29); /* datasheet: typ=22, max=29 */
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memset(buf, 0, sizeof(buf));
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read(fd, buf, 3);
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dump_buf("Relative humidity sample data: ", buf, 3);
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*rh = 125 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 6;
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return 0;
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}
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int sht2x_get_serialnumber(int fd, uint8_t *serialnumber, int size)
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{
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uint8_t buf[4];
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if( fd<0 || !serialnumber || size!=8 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/* Read SerialNumber from Location 1 */
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memset(buf, 0, sizeof(buf));
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buf[0] = 0xfa; /* command for readout on-chip memory */
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buf[1] = 0x0f; /* on-chip memory address */
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write(fd, buf, 2);
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memset(buf, 0, sizeof(buf));
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read(fd, buf, 4);
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serialnumber[5]=buf[0]; /* Read SNB_3 */
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serialnumber[4]=buf[1]; /* Read SNB_2 */
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serialnumber[3]=buf[2]; /* Read SNB_1 */
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serialnumber[2]=buf[3]; /* Read SNB_0 */
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/* Read SerialNumber from Location 2 */
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memset(buf, 0, sizeof(buf) );
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buf[0]=0xfc; /* command for readout on-chip memory */
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buf[1]=0xc9; /* on-chip memory address */
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write(fd, buf, 2);
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memset(buf, 0, sizeof(buf) );
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read(fd, buf, 4);
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serialnumber[1]=buf[0]; /* Read SNC_1 */
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serialnumber[0]=buf[1]; /* Read SNC_0 */
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serialnumber[7]=buf[2]; /* Read SNA_1 */
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serialnumber[6]=buf[3]; /* Read SNA_0 */
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dump_buf("SHT2x Serial number: ", serialnumber, 8);
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return 0;
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}
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#elif (defined I2C_API_IOCTL) /* Use I2C userspace driver read/write API */
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int sht2x_softreset(int fd)
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{
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struct i2c_msg msg;
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struct i2c_rdwr_ioctl_data sht2x_data;
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uint8_t buf[2];
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if( fd<0 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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msg.addr= 0x40;
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msg.flags=0; //write
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msg.len= 1;
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msg.buf= buf;
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msg.buf[0]=SOFTRESET;
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sht2x_data.nmsgs= 1;
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sht2x_data.msgs= &msg;
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if( ioctl(fd, I2C_RDWR, &sht2x_data) < 0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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return -2;
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}
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msleep(50);
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return 0;
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}
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int sht2x_init(void)
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{
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int fd;
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if( (fd=open("/dev/i2c-1", O_RDWR)) < 0)
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{
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printf("i2c device open failed: %s\n", strerror(errno));
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return -1;
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}
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if( sht2x_softreset(fd) < 0 )
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{
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printf("SHT2x softreset failure\n");
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return -2;
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}
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return fd;
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}
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int sht2x_get_serialnumber(int fd, uint8_t *serialnumber, int size)
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{
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struct i2c_msg msgs[2];
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struct i2c_rdwr_ioctl_data sht2x_data;
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uint8_t sbuf[2];
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uint8_t rbuf[4];
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if( fd<0 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/*+------------------------------------------+
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*| Read SerialNumber from Location 1 |
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*+------------------------------------------+*/
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msgs[0].addr= 0x40;
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msgs[0].flags=0; //write
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msgs[0].len= 2;
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msgs[0].buf= sbuf;
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msgs[0].buf[0]=0xfa; /* command for readout on-chip memory */
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msgs[0].buf[1]=0x0f; /* on-chip memory address */
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msgs[1].addr=0x40;
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msgs[1].flags=I2C_M_RD; //write
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msgs[1].len= 4;
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msgs[1].buf= rbuf;
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sht2x_data.nmsgs= 2;
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sht2x_data.msgs= msgs;
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if( ioctl(fd, I2C_RDWR, &sht2x_data) < 0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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return -2;
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}
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serialnumber[5]=rbuf[0]; /* Read SNB_3 */
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serialnumber[4]=rbuf[1]; /* Read SNB_2 */
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serialnumber[3]=rbuf[2]; /* Read SNB_1 */
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serialnumber[2]=rbuf[3]; /* Read SNB_0 */
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/*+------------------------------------------+
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*| Read SerialNumber from Location 2 |
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*+------------------------------------------+*/
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msgs[0].addr= 0x40;
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msgs[0].flags=0; //write
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msgs[0].len= 2;
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msgs[0].buf= sbuf;
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msgs[0].buf[0]=0xfc; /* command for readout on-chip memory */
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msgs[0].buf[1]=0xc9; /* on-chip memory address */
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msgs[1].addr=0x40;
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msgs[1].flags=I2C_M_RD; //write
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msgs[1].len= 4;
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msgs[1].buf= rbuf;
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sht2x_data.nmsgs= 2;
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sht2x_data.msgs= msgs;
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if( ioctl(fd, I2C_RDWR, &sht2x_data) < 0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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return -2;
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}
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serialnumber[1]=rbuf[0]; /* Read SNC_1 */
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serialnumber[0]=rbuf[1]; /* Read SNC_0 */
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serialnumber[7]=rbuf[2]; /* Read SNA_1 */
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serialnumber[6]=rbuf[3]; /* Read SNA_0 */
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dump_buf("SHT2x Serial number: ", serialnumber, 8);
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return 0;
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}
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int sht2x_get_temp_humidity(int fd, float *temp, float *rh)
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{
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struct i2c_msg msg;
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struct i2c_rdwr_ioctl_data sht2x_data;
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uint8_t buf[4];
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if( fd<0 )
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{
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printf("%s line [%d] %s() get invalid input arguments\n", __FILE__, __LINE__, __func__ );
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return -1;
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}
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/*+------------------------------------------+
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*| measure and get temperature |
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*+------------------------------------------+*/
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msg.addr= 0x40;
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msg.flags=0; //write
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msg.len= 1;
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msg.buf= buf;
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msg.buf[0]=TRIGGER_TEMPERATURE_NO_HOLD; /* trigger temperature without hold I2C bus */
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sht2x_data.nmsgs= 1;
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sht2x_data.msgs= &msg;
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if( ioctl(fd, I2C_RDWR, &sht2x_data) < 0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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return -2;
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}
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msleep(85);
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memset(buf, 0, sizeof(buf));
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msg.addr=0x40;
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msg.flags=I2C_M_RD; //write
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msg.len= 3;
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msg.buf= buf;
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sht2x_data.nmsgs= 1;
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sht2x_data.msgs= &msg;
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if( ioctl(fd, I2C_RDWR, &sht2x_data) < 0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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return -2;
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}
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//dump_buf("Temperature sample data: ", buf, 3);
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*temp = 175.72 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 46.85;
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/*+------------------------------------------+
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*| measure and get relative humidity |
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*+------------------------------------------+*/
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msg.addr= 0x40;
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msg.flags=0; //write
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msg.len= 1;
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msg.buf= buf;
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msg.buf[0]=TRIGGER_HUMIDITY_NO_HOLD; /* trigger humidity without hold I2C bus */
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sht2x_data.nmsgs= 1;
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sht2x_data.msgs= &msg;
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if( ioctl(fd, I2C_RDWR, &sht2x_data) < 0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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return -2;
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}
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msleep(29);
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memset(buf, 0, sizeof(buf));
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msg.addr=0x40;
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msg.flags=I2C_M_RD; //write
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msg.len= 3;
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msg.buf= buf;
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sht2x_data.nmsgs= 1;
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sht2x_data.msgs= &msg;
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if( ioctl(fd, I2C_RDWR, &sht2x_data) < 0 )
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{
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printf("%s() ioctl failure: %s\n", __func__, strerror(errno));
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return -2;
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}
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//dump_buf("Relative humidity sample data: ", buf, 3);
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*rh = 125 * (((((int) buf[0]) << 8) + buf[1]) / 65536.0) - 6;
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return 0;
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}
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#endif
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