Building a Sophisticated Clock from VW Golf

Overview

The project was designed around the ATmega8 microcontroller, to be made as a digital clock wherein 13mm high characters will be displayed in a 16x1 LCD screen for more comfortable readout.

Details

A DS1305 real-time clock independent of the microprocessor is used to update the date and time continuously. It can also be used for different temperature. One good feature on this device is that even if the engine is already turned OFF, the date and time is always visible on the display simultaneously. The computer will keep on operating if it already turned OFF since the contact is always ON.

To handle the system in power-safe mode when necessary, the contact on the display should be disabled. Even when the vehicle is not used for long time, the power consumption is kept as low as possible in order to prevent the battery discharge or keep it minimal. A MAX667 5V regulator is used to get a stable 5V power since it has its own power consumption of only 20uA. The backlight of all measurements is put to stop and the power to the external ADC is turned OFF in power-save mode.