1*4882a593SmuzhiyunKernel driver sht15 2*4882a593Smuzhiyun=================== 3*4882a593Smuzhiyun 4*4882a593SmuzhiyunAuthors: 5*4882a593Smuzhiyun 6*4882a593Smuzhiyun * Wouter Horre 7*4882a593Smuzhiyun * Jonathan Cameron 8*4882a593Smuzhiyun * Vivien Didelot <vivien.didelot@savoirfairelinux.com> 9*4882a593Smuzhiyun * Jerome Oufella <jerome.oufella@savoirfairelinux.com> 10*4882a593Smuzhiyun 11*4882a593SmuzhiyunSupported chips: 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun * Sensirion SHT10 14*4882a593Smuzhiyun 15*4882a593Smuzhiyun Prefix: 'sht10' 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun * Sensirion SHT11 18*4882a593Smuzhiyun 19*4882a593Smuzhiyun Prefix: 'sht11' 20*4882a593Smuzhiyun 21*4882a593Smuzhiyun * Sensirion SHT15 22*4882a593Smuzhiyun 23*4882a593Smuzhiyun Prefix: 'sht15' 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun * Sensirion SHT71 26*4882a593Smuzhiyun 27*4882a593Smuzhiyun Prefix: 'sht71' 28*4882a593Smuzhiyun 29*4882a593Smuzhiyun * Sensirion SHT75 30*4882a593Smuzhiyun 31*4882a593Smuzhiyun Prefix: 'sht75' 32*4882a593Smuzhiyun 33*4882a593SmuzhiyunDatasheet: Publicly available at the Sensirion website 34*4882a593Smuzhiyun 35*4882a593Smuzhiyun http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf 36*4882a593Smuzhiyun 37*4882a593SmuzhiyunDescription 38*4882a593Smuzhiyun----------- 39*4882a593Smuzhiyun 40*4882a593SmuzhiyunThe SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature 41*4882a593Smuzhiyunsensors. 42*4882a593Smuzhiyun 43*4882a593SmuzhiyunThe devices communicate using two GPIO lines. 44*4882a593Smuzhiyun 45*4882a593SmuzhiyunSupported resolutions for the measurements are 14 bits for temperature and 12 46*4882a593Smuzhiyunbits for humidity, or 12 bits for temperature and 8 bits for humidity. 47*4882a593Smuzhiyun 48*4882a593SmuzhiyunThe humidity calibration coefficients are programmed into an OTP memory on the 49*4882a593Smuzhiyunchip. These coefficients are used to internally calibrate the signals from the 50*4882a593Smuzhiyunsensors. Disabling the reload of those coefficients allows saving 10ms for each 51*4882a593Smuzhiyunmeasurement and decrease power consumption, while losing on precision. 52*4882a593Smuzhiyun 53*4882a593SmuzhiyunSome options may be set via sysfs attributes. 54*4882a593Smuzhiyun 55*4882a593SmuzhiyunNotes: 56*4882a593Smuzhiyun * The regulator supply name is set to "vcc". 57*4882a593Smuzhiyun * If a CRC validation fails, a soft reset command is sent, which resets 58*4882a593Smuzhiyun status register to its hardware default value, but the driver will try to 59*4882a593Smuzhiyun restore the previous device configuration. 60*4882a593Smuzhiyun 61*4882a593SmuzhiyunPlatform data 62*4882a593Smuzhiyun------------- 63*4882a593Smuzhiyun 64*4882a593Smuzhiyun* checksum: 65*4882a593Smuzhiyun set it to true to enable CRC validation of the readings (default to false). 66*4882a593Smuzhiyun* no_otp_reload: 67*4882a593Smuzhiyun flag to indicate not to reload from OTP (default to false). 68*4882a593Smuzhiyun* low_resolution: 69*4882a593Smuzhiyun flag to indicate the temp/humidity resolution to use (default to false). 70*4882a593Smuzhiyun 71*4882a593SmuzhiyunSysfs interface 72*4882a593Smuzhiyun--------------- 73*4882a593Smuzhiyun 74*4882a593Smuzhiyun================== ========================================================== 75*4882a593Smuzhiyuntemp1_input temperature input 76*4882a593Smuzhiyunhumidity1_input humidity input 77*4882a593Smuzhiyunheater_enable write 1 in this attribute to enable the on-chip heater, 78*4882a593Smuzhiyun 0 to disable it. Be careful not to enable the heater 79*4882a593Smuzhiyun for too long. 80*4882a593Smuzhiyuntemp1_fault if 1, this means that the voltage is low (below 2.47V) and 81*4882a593Smuzhiyun measurement may be invalid. 82*4882a593Smuzhiyunhumidity1_fault same as temp1_fault. 83*4882a593Smuzhiyun================== ========================================================== 84