/*
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* sht20.c
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*
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* Created on: Jan 19, 2023
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* Author: Wenxue
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*/
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#include <sht20.h>
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#include <stdio.h>
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#include <string.h>
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#define delay_ms(x) HAL_Delay(x)
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enum
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{
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TRIG_T_MEASUREMENT_HM = 0xE3, // command trig. temp meas. hold master
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TRIG_RH_MEASUREMENT_HM = 0xE5, // command trig. humidity meas. hold master
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TRIG_T_MEASUREMENT_POLL = 0xF3, // command trig. temp meas. no hold master
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TRIG_RH_MEASUREMENT_POLL = 0xF5, // command trig. humidity meas. no hold master
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USER_REG_W = 0xE6, // command writing user register
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USER_REG_R = 0xE7, // command reading user register
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SOFT_RESET = 0xFE // command soft reset
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};
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//#define CONFIG_SHT2X_DEBUG
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#ifdef CONFIG_SHT2X_DEBUG
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static inline void dump_buf(uint8_t *buf, uint32_t size)
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{
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int i;
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if(!buf)
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return ;
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for(i=0; i<size; i++)
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printf("%02x ", buf[i]);
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printf("\r\n");
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}
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#endif
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#ifdef CONFIG_SHT2X_DEBUG
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#define sht2x_print(format,args...) printf(format, ##args)
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#else
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#define sht2x_print(format,args...) do{} while(0);
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#endif
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static int sht2x_measure_value(uint8_t command, uint16_t *val);
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static int sht2x_softreset(void);
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uint32_t sht20_sample_TrH(uint32_t *temperature, uint32_t *humdity)
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{
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uint16_t sT;
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uint16_t sRH;
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uint32_t T;
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uint32_t RH;
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uint32_t TRH=TRH_FAIL_VAL;
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i2c_term(SHT2X_I2CBUS);
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if( i2c_init(SHT2X_I2CBUS, SHT2X_CHIPADDR) )
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{
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sht2x_print("SHT20 initial I2C bus failed.\r\n");
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return TRH;
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}
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if( sht2x_softreset() )
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{
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sht2x_print("SHT20 soft reset failed.\r\n");
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goto OUT;
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}
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sht2x_print("Start to measurement temperature...\r\n");
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if( sht2x_measure_value(TRIG_T_MEASUREMENT_POLL, &sT) < 0 )
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{
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sht2x_print("I2C measurement failed\r\n");
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goto OUT;
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}
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T=(uint32_t)(100*(float)((175.72*sT)/65536-46.85));
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sht2x_print("Measure temperature: %lu.%lu\r\n", T/100, T%100);
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if( temperature )
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*temperature=T;
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TRH = ((T/100)<<8|(T%100))<<16 | 0xFFFF;
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sht2x_print("Start to measurement relative humidity...\r\n");
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if( sht2x_measure_value(TRIG_RH_MEASUREMENT_POLL, &sRH) < 0 )
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{
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goto OUT;
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}
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RH=(uint32_t)(100*(float)((125*sRH)/65535-6.0));
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sht2x_print("Measure relative humidity: %lu.%lu%%\r\n", RH/100, RH%100);
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if( humdity )
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*humdity=RH;
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TRH &= 0xFFFF0000 | ((uint16_t)RH/100)<<8 | ((uint16_t)RH%100) ;
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OUT:
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i2c_term(SHT2X_I2CBUS);
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return TRH;
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}
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int sht2x_softreset(void)
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{
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uint8_t command = SOFT_RESET;
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int rv = 0;
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sht2x_print("Start soft reset sht2x\r\n");
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rv=i2c_write(SHT2X_I2CBUS, &command, 1);
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if( rv )
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{
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sht2x_print("SHT2X send soft reset command 0x%0x failure: rv=0x%02x\r\n", command, rv);
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return -rv;
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}
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delay_ms(15);
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return 0;
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}
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static int sht2x_checkcrc(uint8_t *data, uint8_t bytes, uint8_t checksum)
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{
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uint8_t crc = 0;
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uint8_t i;
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uint8_t bit;
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//calculates 8-Bit checksum with given polynomial
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for (i=0; i<bytes; ++i)
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{
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crc ^= (data[i]);
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for (bit=8; bit>0; --bit)
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{
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if (crc & 0x80)
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crc = (crc << 1) ^ 0x0131; //POLYNOMIAL;
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else
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crc = (crc << 1);
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}
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}
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if (crc != checksum)
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{
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return -1;
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}
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else
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{
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return 0;
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}
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}
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static int sht2x_measure_value(uint8_t command, uint16_t *val)
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{
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uint8_t buf[3]; /* I2C������buffer */
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int count=4; /* �ܹ����Ĵ��� */
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if( !val )
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{
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sht2x_print("SHT2X invalid input arguments\r\n");
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return -1;
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}
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if(TRIG_T_MEASUREMENT_POLL!=command && TRIG_RH_MEASUREMENT_POLL !=command )
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{
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sht2x_print("SHT2X unsupport command: 0x%0x\r\n", command);
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return -2;
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}
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if( NO_ERROR != i2c_write(SHT2X_I2CBUS, &command, 1) )
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{
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sht2x_print("SHT2X send measure command 0x%0x failure\r\n", command);
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return -3;
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}
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if(TRIG_T_MEASUREMENT_POLL == command)
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delay_ms(85);
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else
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delay_ms(29);
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while(count--)
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{
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memset(buf, 0, 3);
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if( !i2c_read(SHT2X_I2CBUS, buf, 3) )
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{
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break;
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}
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delay_ms(5);
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}
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if( sht2x_checkcrc(buf, 2, buf[2])< 0 )
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{
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#ifdef CONFIG_SHT2X_DEBUG
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sht2x_print("Measurement data checksum failure:\r\n");
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dump_buf(buf, 3);
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#endif
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return -4;
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}
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if(TRIG_T_MEASUREMENT_POLL == command)
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*val = buf[0]<<8|(buf[1]&0xFC); //14bits(1111 1100)
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else
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*val = buf[0]<<8|(buf[1]&0xFF); //12bits(1100 0000)
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sht2x_print("Measurement temperature value: 0x%04x\r\n", *val);
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return 0;
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}
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