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Open PID controller based on Arduino

There are many situation in real world where you need to set up an automatic control. This can be a simple heater, cooler where you would set a desired temperature and let the device sustain this level. Usually such controller has a sensor input and actuator. In this particular case temperature is measured using DS18B20 sensor while heater is controlled through Solid State Relay (SSR). Hardware part is pretty obvious. What about software? You could simply program if – then based logic in to microcontroller and have it working. Well this is partially true, but in real world things have inertia. What means that things cannot started and stopped immediately. Simple compare algorithms in many cases lead to overshoots and rough characteristics that sometimes can be damaging. So there is… Continue reading

Open source PID controller at your service

Sometimes you need a more precise control of things rather than switching on and off with some hysteresis. This is why PID control was developed. PID control is known as Proportional, Integral and Derivative control where each part brings a portion of fine tune to end control signal. So instead of having rough characteristics you get pretty fine and optimal curve, say of oven temperature. osPID have published their initial version of open hardware PID controller which is based on Arduino compatible Atmega328P microcontroller. The design of osPID is modular that consists of three plug-able boards: Main board with microcontroller, buttons and LCD, Input card where sensor input information is captured an output card which controls actual device. Depending on controlled device input and output cards can be swapped to… Continue reading