On Wed, Jun 27, 2012 at 07:41:18AM +0000, Iain Paton wrote: > On 06/22/2012 03:34 PM, Guenter Roeck wrote: > > >> + * Response time for the sensor is measured in seconds, so we have > > > > in seconds ? > Hi Iain, How about "Response time for the sensor to react to changes in external conditions is several seconds, so we have ..." > So, how to word it then... In the datasheets words, "The measurement cycle > duration is typically 36.65 ms for temperature and humidity readings." > > However we also have > > Table 2. Humidity Performance Specifications > Characteristic Condition Min Typ Max Unit > Response time airflow minimum 20 l/min – 6 8 s > > > Table 3. Temperature Performance Specifications > Characteristic Condition Min Typ Max Unit > Response time 1/e slow moving air 5 - 30 s > > So although we can run a measurement in around 40ms it will take the sensor longer > to react to a change. > > I agree this needs to be clear, or there's no point to the comment. Just that > you're asking suggests it's not clear enough. Suggestions ? > > > How about this: > > While the measurement can be completed in ~40ms the sensor takes much longer to react > to a change in external conditions. How quickly it reacts depends on airflow and other > factors outwith our control. > The datasheet specifies maximum 'Response time' for humidity at 8s and temperature at > 30s under specified conditions. > We therefore choose to only read the sensor at most once per second. This trades off > pointless activity polling the sensor much faster than it can react against better > response times in conditions more favourable than specified in the datasheet. > Sounds like an excellent note to add to the Documentation file. Thanks, Guenter _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
