Temperature logger out of building blocks

Husham wanted simple portable temperature logger that would work outside reliably. He’s built electronic part out of several building blocks where control is given to Arduino Nano. Precise time is kept on RTC module based on DS1307. Temperature is measured with LM35 sensor. Data then is logged in to SD card which also is interfaced by using SD card module. Current temperature and time is also displayed on LCD screen. Special care is taken on building enclosure and adding basic control. So instead of using regular buttons he decided to add couple Hall effect sensors that would act as switches when magnet is brought close to area. One Hall sensor is used to turn LCD backlight and another for resetting microcontroller. Device is powered with couple Li-Ion batteries. Since it only logs data to SD card, eventually you need to take SD card out in order to load data to computer. Probably wireless interface like Bluetooth could make things much easier. Continue reading

Arduino displays min and max temperatures

Arduino is a great way to do simple projects like this because it doesn’t require lots of messing with making PCBs and interfacing. Simple project can be done by attaching things directly and or by using protoboard. In this project Arduino reads temperature values from LM35DZ temperature sensor via analog input 0. To display min and max temperature values there are a LCD attached in 4 bit mode. Of course it also shows current temperature. So it may be convenient to set it for some certain time to see what the temperature change was during 24 hr. Continue reading