This is my first post here so first of all I would like to introduce myself, My name is Ryan, i am reasonable with basic electronics, & a complete noob when it comes to programming.
I am in the process of building an arduino based cloud sensor / weather station. So far i have managed to get most of the sensors set up, I am using the MLX90614 IR thermometer, a BMP085 barometric pressure sensor, a SHT15 humidity/temp sensor & an LDR. A wetness sensor to detect rain drops & wind speed sensor are also going to be needed, but i don't have those yet. Also i plan to add a wind direction sensor & a rain fall amount sensor, but that depends on how much code space i have left on the arduino.
this allows me to compare the sky temperature with the ambient temperature and work out if the sky is clear or cloudy, but if any moisture were to collect on the IR sensor i would get a false reading of the sky temperature, so i need to add some form of heater to prevent dew collecting or evaporate any surface moisture after rain.
in order to detect rain i will use either a wet leaf sensor or an optical sensor like those used in cars to control windscreen wipers, it will simply indicate either a wet or dry condition.
the ambient temperature & dew point measured using the SHT15 should be monitored and regulate the heater to keep the body of the MLX90614 & rain sensor above freezing / dew point (whichever is detected first) the MLX90614 has an internal temp sensor that will be used to measure the temp of the rain/IR sensors. Also in the event that the rain sensor detects a wet condition the heater should heat the rain & IR sensors to 60-70c to evaporate the moisture away when the rain has stopped.
whilst i appreciate that the arduino cannot technically do two processes simultaneously will it be possible to manage the heater control & take sensor readings (& Serial.print them) once every 1-2 seconds?
If this is possible to do can anyone offer me any advice on creating the code for such a task? if it helps i can also provide details of the relevant variables used for the outputs from the different sensors
Also i could do with some assistance on the design of the actual heater element & any electronics needed to provide the heater with sufficient current as i am pretty sure that the PWM on board the arduino will not be up to the job on its own. it would also be good to keep the potentially "noisy" heater circuit isolated from the rest of the more delicate electronics.
For the heater element its self i am thinking of using either a bunch of resistors or nichrome wire, but i have no idea of any of the details, so any pointers here would also be useful, the whole project will probably live in a box with a lid approx 100mm x 100mm and the whole surface of the lid will need to be heated.
Thanks in advance. Ryan.