213 lines
7.4 KiB
C
213 lines
7.4 KiB
C
/*
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* Copyright (c) 2019, 2022 Erich Styger
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* All rights reserved.
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*
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* Driver for the Sensirion SHT40 Temperature/Humidity sensor
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include "McuSHT40config.h"
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#include "McuSHT40.h"
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#include "McuGenericI2C.h"
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#include "McuUtility.h"
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#include <stddef.h> /* for NULL */
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#define SHT40_MEAS_HIGHREP 0xFD
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#define SHT40_MEAS_MEDREP 0xF6
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#define SHT40_MEAS_LOWREP 0xE0
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#define SHT40_READSERIALNUM 0x89
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#define SHT40_SOFTRESET 0x94
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#define SHT40_HEATER_200MW_1000MS_PRECISION_HIGH 0x39 /* activate heater with 200mW for 1s, including a high precision measurement just before deactivation */
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#define SHT40_HEATER_200MW_100MS_PRECISION_HIGH 0x32 /* activate heater with 200mW for 0.1s, including a high precision measurement just before deactivation */
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#define SHT40_HEATER_110MW_1000MS_PRECISION_HIGH 0x2F /* activate heater with 110mW for 1s, including a high precision measurement just before deactivation */
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#define SHT40_HEATER_110MW_100MS_PRECISION_HIGH 0x24 /* activate heater with 110mW for 0.1s, including a high precision measurement just before deactivation */
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#define SHT40_HEATER_20MW_1000MS_PRECISION_HIGH 0x1E /* activate heater with 20mW for 1s, including a high precision measurement just before deactivation */
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#define SHT40_HEATER_20MW_100MS_PRECISION_HIGH 0x15 /* activate heater with 20mW for 0.1s, including a high precision measurement just before deactivation */
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/* status bits of the Status register (0xF32D) */
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#define SHT40_STATUS_ALERT_PENDING (1<<15) /* 0: no pending alert, 1: at least one pending alert */
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#define SHT40_STATUS_HEATER_ON (1<<13) /* 0: heater OFF, 1: heater ON */
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#define SHT40_STATUS_RH_TRACKING_ALERT (1<<11) /* 0: no RH tracking alert, 1: alert */
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#define SHT40_STATUS_T_TRACKING_ALERT (1<<10) /* 0: no T tracking alert, 1: alert */
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#define SHT40_STATUS_SYSTEM_RESET (1<<4) /* 0: no reset detected since last clear status register command, 1: reset detected (hard reset, soft reset or supply fail */
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#define SHT40_STATUS_CMD_STATUS (1<<1) /* 0: last command executed successfully; 1: last command not processed, it was either invalid, failed the internal command checksum */
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#define SHT40_STATUS_WRITE_CRC_STATUS (1<<0) /* 0: checksum of last write transfer was correct, 1: checksum of last write transfer failed */
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#define SHT40_CRC8_POLYNOMIAL 0x31 /* Seed for CRC polynomial */
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#define SHT40_CRC8_INIT 0xFF /* Init value for CRC */
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static uint8_t SHT40_GenerateCRC(uint8_t *data, uint8_t datalen) {
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/* calculates 8-Bit checksum with given polynomial */
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uint8_t crc = SHT40_CRC8_INIT;
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uint8_t b;
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uint8_t i;
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for (i=0; i<datalen; i++) {
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crc ^= data[i];
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for (b=0; b<8; b++) {
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if (crc & 0x80) {
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crc = (crc<<1)^SHT40_CRC8_POLYNOMIAL;
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} else {
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crc <<= 1;
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}
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}
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}
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return crc;
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}
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static uint8_t SHT40_WriteCommand(uint16_t cmd) {
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uint8_t buf[2];
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buf[0] = cmd>>8;
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buf[1] = cmd&0xff;
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return McuGenericI2C_WriteAddress(McuSHT40_CONFIG_I2C_ADDR, buf, sizeof(buf), NULL, 0);
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}
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uint8_t SHT40_ReadSerialNumber(uint32_t *serial) {
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uint8_t res;
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uint8_t cmd[1];
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uint8_t readbuffer[6];
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cmd[0] = SHT40_READSERIALNUM;
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res = McuGenericI2C_ReadAddressWait(McuSHT40_CONFIG_I2C_ADDR, cmd, sizeof(cmd), 20, readbuffer, sizeof(readbuffer));
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if (res!=ERR_OK) {
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*serial = 0;
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return res;
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}
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*serial = (readbuffer[0]<<24)|(readbuffer[1]<<16);
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if (readbuffer[2] != SHT40_GenerateCRC(readbuffer, 2)) {
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return ERR_CRC;
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}
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*serial |= (readbuffer[3]<<8)|readbuffer[4];
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if (readbuffer[5] != SHT40_GenerateCRC(readbuffer+3, 2)) {
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return ERR_CRC;
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}
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return res;
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}
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uint8_t McuSHT40_Reset(void) {
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return SHT40_WriteCommand(SHT40_SOFTRESET);
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}
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uint8_t McuSHT40_ReadTempHum(float *temperature, float *humidity) {
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float stemp, shum;
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uint16_t ST, SRH;
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uint8_t readbuffer[6];
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uint8_t res;
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uint8_t cmd[1];
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cmd[0] = SHT40_MEAS_HIGHREP;
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res = McuGenericI2C_ReadAddressWait(McuSHT40_CONFIG_I2C_ADDR, cmd, sizeof(cmd), 20, readbuffer, sizeof(readbuffer));
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if (res!=ERR_OK) {
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return res;
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}
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ST = (readbuffer[0]<<8)|readbuffer[1];
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if (readbuffer[2] != SHT40_GenerateCRC(readbuffer, 2)) {
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return ERR_CRC;
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}
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SRH = (readbuffer[3]<<8)|readbuffer[4];
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if (readbuffer[5] != SHT40_GenerateCRC(readbuffer+3, 2)) {
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return ERR_CRC;
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}
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stemp = ST;
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stemp *= 175;
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stemp /= 0xffff;
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stemp = -45 + stemp;
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*temperature = stemp;
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shum = SRH;
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shum *= 125;
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shum /= 0xFFFF;
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shum = -6 + shum;
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if (shum>100.0f) {
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shum = 100.0f;
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} else if (shum<0.0f) {
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shum = 0.0f;
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}
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*humidity = shum;
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return ERR_OK;
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}
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#if MCUSHT40_CONFIG_PARSE_COMMAND_ENABLED
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static uint8_t PrintStatus(const McuShell_StdIOType *io) {
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uint8_t buf[32];
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uint32_t serial;
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float temperature, humidity;
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uint8_t res;
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McuShell_SendStatusStr((unsigned char*)"SHT40", (unsigned char*)"Sensirion SHT40 sensor status\r\n", io->stdOut);
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McuUtility_strcpy(buf, sizeof(buf), (unsigned char*)"0x");
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McuUtility_strcatNum8Hex(buf, sizeof(buf), McuSHT40_CONFIG_I2C_ADDR);
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McuUtility_strcat(buf, sizeof(buf), (unsigned char*)"\r\n");
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McuShell_SendStatusStr((unsigned char*)" addr", buf, io->stdOut);
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res = SHT40_ReadSerialNumber(&serial);
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if (res==ERR_OK) {
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McuUtility_strcpy(buf, sizeof(buf), (unsigned char*)"0x");
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McuUtility_strcatNum32Hex(buf, sizeof(buf), serial);
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McuUtility_strcat(buf, sizeof(buf), (unsigned char*)"\r\n");
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} else {
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McuUtility_strcpy(buf, sizeof(buf), (unsigned char*)"ERROR\r\n");
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}
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McuShell_SendStatusStr((unsigned char*)" serial", buf, io->stdOut);
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if(McuSHT40_ReadTempHum(&temperature, &humidity)==ERR_OK) {
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McuUtility_NumFloatToStr(buf, sizeof(buf), temperature, 2);
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McuUtility_chcat(buf, sizeof(buf), '\xB0'); /* add '°' (ASCII 0xB0) it as single char, as with UTF-8 it might end up in two bytes inside a string */
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McuUtility_strcat(buf, sizeof(buf), (unsigned char*)"C\r\n");
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McuShell_SendStatusStr((unsigned char*)" temp", buf, io->stdOut);
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McuUtility_NumFloatToStr(buf, sizeof(buf), humidity, 2);
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McuUtility_strcat(buf, sizeof(buf), (unsigned char*)" RH\r\n");
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McuShell_SendStatusStr((unsigned char*)" humidity", buf, io->stdOut);
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} else {
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McuShell_SendStatusStr((unsigned char*)" ERROR:", (unsigned char*)" *** ERROR reading sensor values\r\n", io->stdOut);
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}
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return ERR_OK;
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}
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static uint8_t PrintHelp(const McuShell_StdIOType *io) {
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McuShell_SendHelpStr((unsigned char*)"SHT40", (unsigned char*)"Group of SHT40 commands\r\n", io->stdOut);
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McuShell_SendHelpStr((unsigned char*)" help|status", (unsigned char*)"Print help or status information\r\n", io->stdOut);
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return ERR_OK;
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}
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#endif /* MCUSHT40_CONFIG_PARSE_COMMAND_ENABLED */
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#if MCUSHT40_CONFIG_PARSE_COMMAND_ENABLED
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uint8_t McuSHT40_ParseCommand(const unsigned char* cmd, bool *handled, const McuShell_StdIOType *io) {
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uint8_t res = ERR_OK;
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if (McuUtility_strcmp((char*)cmd, McuShell_CMD_HELP) == 0
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|| McuUtility_strcmp((char*)cmd, "SHT40 help") == 0)
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{
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*handled = TRUE;
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return PrintHelp(io);
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} else if ( (McuUtility_strcmp((char*)cmd, McuShell_CMD_STATUS)==0)
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|| (McuUtility_strcmp((char*)cmd, "SHT40 status")==0)
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)
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{
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*handled = TRUE;
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res = PrintStatus(io);
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}
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return res;
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}
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#endif /* SHT40_CONFIG_PARSE_COMMAND_ENABLED */
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void McuSHT40_Init(void) {
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/* noting to do */
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}
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void McuSHT40_Deinit(void) {
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/* nothing to do */
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}
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