Hi, I wonder if the rate of reading is overwhelming the capacitor charging in the circuit. The DS2438 humidity sensor design creates Vdd from the data line, if I remember correctly.
Do the problems resolve if you delay readings by, say, 60 seconds intervals? I doubt your humidity really changes that fast. Paul On Fri, Jun 12, 2015 at 6:28 AM, Michele Marcon <m.mar...@riello-ups.com> wrote: > Hello Mr. Alfille, > I'm using owfs for monitoring the DS2438 device over 1-wire with I2C bus. > > I've noticed some errors in reading the humidity value; here is an extract > of my log: > > Fri Jun 12 11:15:39 CEST 2015: hum 41 1.92 4.66 t_ist 311.562 t_avg 311 > t_max 312 312 > Fri Jun 12 11:15:41 CEST 2015: hum 41 1.92 4.66 t_ist 311.562 t_avg 311 > t_max 312 312 > Fri Jun 12 11:15:43 CEST 2015: hum 41 1.92 4.66 t_ist 311.562 t_avg 311 > t_max 312 312 > Fri Jun 12 11:15:45 CEST 2015: hum 41 1.92 4.66 t_ist 311.562 t_avg 311 > t_max 312 312 > Fri Jun 12 11:15:48 CEST 2015: hum 41 1.92 1.92 t_ist 312.812 t_avg 311 > t_max 312 312 > Fri Jun 12 11:15:50 CEST 2015: hum -119 1.92 1.92 t_ist 312.812 t_avg > 311 t_max 312 312 > Fri Jun 12 11:15:52 CEST 2015: hum -119 1.92 1.92 t_ist 312.812 t_avg > 312 t_max 312 312 > Fri Jun 12 11:15:54 CEST 2015: hum -119 1.92 1.92 t_ist 312.812 t_avg > 312 t_max 312 312 > Fri Jun 12 11:15:56 CEST 2015: hum -119 1.92 1.92 t_ist 312.812 t_avg > 312 t_max 312 312 > Fri Jun 12 11:15:59 CEST 2015: hum -119 1.92 1.91 t_ist 311.562 t_avg > 312 t_max 312 312 > Fri Jun 12 11:16:01 CEST 2015: hum -118 1.92 1.91 t_ist 311.562 t_avg > 312 t_max 312 312 > Fri Jun 12 11:16:03 CEST 2015: hum -118 1.92 1.91 t_ist 311.562 t_avg > 311 t_max 312 312 > Fri Jun 12 11:16:05 CEST 2015: hum -118 1.92 1.91 t_ist 311.562 t_avg > 311 t_max 312 312 > Fri Jun 12 11:16:07 CEST 2015: hum -118 1.92 1.91 t_ist 311.562 t_avg > 311 t_max 312 312 > Fri Jun 12 11:16:40 CEST 2015: hum 40 1.91 4.66 t_ist 310.938 t_avg 311 > t_max 312 312 > Fri Jun 12 11:16:42 CEST 2015: hum 40 1.91 4.66 t_ist 310.938 t_avg 311 > t_max 312 312 > Fri Jun 12 11:16:44 CEST 2015: hum 40 1.91 4.66 t_ist 310.938 t_avg 311 > t_max 312 312 > Fri Jun 12 11:16:46 CEST 2015: hum 40 1.91 4.66 t_ist 310.938 t_avg 311 > t_max 312 312 > Fri Jun 12 11:16:48 CEST 2015: hum 40 1.91 4.66 t_ist 310.938 t_avg 311 > t_max 312 312 > Fri Jun 12 11:16:51 CEST 2015: hum 41 1.92 4.66 t_ist 312.188 t_avg 311 > t_max 312 312 > > > In particular, I'd like to show you that the reading of VDD sometimes > return "1.92" or similar values when it should be around "4.66". Do you > have any explanation? > > Thanks for your help, > > > Michele Marcon > > Centro Ricerche > RPS SpA > Viale Europa, 7 > 37045 Legnago VR > Tel. +39 0442 635811 Fax. +39 0442 635934 > Skype Id: - Voip: > E-mail: m.mar...@riello-ups.com > Web: www.riello-ups.com > -------------------------------------------------------------------------- > Per favore non stampare questo messaggio se proprio non รจ > necessario > Please consider the environment before printing this e-mail > -------------------------------------------------------------------------- > > > > >
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