It is a household thermometer connected to the plasma TV (with a PC-VGA input). The system monitors the temperature in the living room, garage and outside on both sides of the house. LCD monitor used in this project provides good quality of the readings.
Sensors used are DS18B20, each of them is connected to a separate pin of uP port. They can be placed with wireless sensors.

The system is very simple and consists of the following elements:
  • 5V power supply (LM7805)
  • processor (Atmega16/32)
  • 4 temperature sensors DS18B20
  • real-time clock (PCF8583+ battery CR2032)
  • 3 microswitches
  • JTAG connector
  • 3,3V power supply (LM1117-3,3V)
  • TeleVGA card


The project was written in C (GCC/WinAVR) and the library of DS18B20 support in Assembler. The whole is divided into functional blocks of type MAIN, VGA, I2C, SPI, RTC, FONT, DS18B20 etc.
Temperature measurement is done every 10 second. In case of detecting no sensor or transmission errors, only the degree Celsius mark is displayed in the selected box.
Displayed colors can easily be changed by changing constant definitions MAIN_COLOR, TIME_COLOR2, etc.
Programming the clock is done by using three butons: ENER, PLUS and MINUS. After pressing ENTER button, the programming mode is triggered, then with the PLUS and MINUS you can change hours, minutes, day of month, month. Transition between the following parameters is done after pressing ENTER. After setting, correctness of date is checked, what means if you set 31. April, it will be corrected to 30. April. When setting the time, seconds are zeroed. The clock does not correct the date for leap years.

The system can be modified for example to change the display color depending on whether you have a positive or negative temperature.

The system was made on universal board. All the necessary sources can be found on the original thread.




Link to original thread (useful attachment) – Termometr 4-kanałowy i zegar, wyświetlanie TVplazma, AVR,DS18B20,PCF8583,teleVGA