The blog of 'The Arduino Guy' aka Mike McRoberts, author of Beginning Arduino.

29 October 2014

Pin Powered Sensor

In an attempt to increase battery life further I've now got the HTU21D humidity and temperature sensor powered by a digital pin from the ATMega328p. In code the sensor is powered up and then back down again in-between reads in an effort to squeeze some more juice out of the battery. I've left the transmits/reads at every 2 seconds again so I can compare the voltage loss with what I've been having over the last few days to see if there is an improvement.

A test of 24 hours should be enough to ascertain if the voltage loss is the same or less than it was previously. Before I made this change the circuit was losing about 0.27 volts per day which would give the battery a life of about a week with 2 second reads/transmits. Ultimately the sensor will be set to only wake up every 60 seconds, which will give a much greater battery life. 


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