[time-nuts] Temperature (environmental) sensors
dmendesf at gmail.com
Tue Jan 3 13:48:13 EST 2017
Yesterday hackaday had a link to a humidy sensor comparison:
Em 03/01/2017 16:03, Mark Sims escreveu:
> I did a LOT of testing environmental sensors when I built my ultrasonic anemometer weather station that is part of a rocket launch control system. The best humidity sensor I found was the DHT21/SHT11/AM2301/SHT15. They run around $3 and can also provide temperature to 0.1C res / 0.5C accuracy. I tested lots of MUCH more expensive humidity sensors and that one agreed the best to my lab grade Vasilia. That said, all humidity sensors are rather sucky.
> For pressure the MS5611 sensor was, by far, the best. It can measure the pressure change equivalent to less than a foot of altitude. It can also provide a high-res temperature reading (of the sensor, not the environment). It uses 24 bit A/D converters. I use a 10 DOF IMU board from Ebay ($10) or you can get the sensor only on a board for around $7.
> The weather station board uses a ATMEGA32 to read all the sensors and outputs an RS-232 stream that looks like NMEA data. It uses four $1 SR04 ultrasonic sensors to measure wind velocity/direction/air temperature. It also supports a UV intensity sensor. It uses the magnetometer/accelerometers on the IMU board as a digital compass so you don't have to orient the anemometer to north. I've used the board without the ultrasonics as an environmental sensor.
> I use sensor noise from the IMUs and Atmel ADCs to implement a true random number generator that feeds the crypto systems that protect the launch controllers from neer-do-wells. The TRNG output passes all tests of randomness with flying colors.
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