Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

YATC 2 – General Appliance Temperature Controller using an ATMega48

Motivated by the amount of energy to be saved and because of the perils of a broken refrigerator – our friends from www.screwdecaf.cx came up with brilliant way of converting almost any and I say any cooling or heating appliance in to a configurable cooling and heating system. What it basically does is get the temperature input from the user – if its above 65F then it assumes that the appliance being driven is a heater and below 65F its a cooler! The brain of the system is an ATMEGA48 microcontroller which converts temperature data from a temp sensor through one of its ADC channels. When data is captured from the temperature sensor and was found out to be less than 65F the ATMega48 will fire up a relay to switch on the heating process – a similar thing happens in cooling, the only difference is that a cooler is powered on not a heater . The YATC 2 does not do regulation through PID [Product – Integral – Derivative] it just compares the current temperature data with a target… Continue reading

Reading Temperature from DS1820 using 1-Wire Protocol

Temperature sensors come in various shapes and sizes, they also come in different colors and number of pins but above all these differences one difference must not be taken for granted- how to read the temperature data from it. Maybe the simplest form of a temperature sensor is the thermistor, it has two wires, and the resistances between these two wires vary depending on the temperature. This type of sensor requires an ADC to convert the analog signal into digital. However modern temperature sensors now come with their built in ADC and their outputs can be accessed serially. There are three commonly used serial protocols SPI, I2C and 1 Wire, these vary on the number of wires and on the way data is accessed. In this project the DS1820 is used to demonstrate how to read temperature data from a temperature sensor which communicates using the 1-Wire protocol. The DS1820 is a three pinned temperature sensor, it actually looks more like a transistor – but it’s not! PIC16F628A was used to read the temperature data from the sensor, after data… Continue reading