Vermes
Advanced Member level 4
It's an easy Atmega voltmeter.
The voltmeter was designed for trying li-ion 18650 cells (used for flashlights) . The voltmeter was closed in a 3-position LED housing.
The board was designed in Eagle and made by thermo-transfer method, using laminate. The board was secured with rosin.
Atmega works on an external clock with a 8MHz generator and an external reference voltage on a TL431. If the internal voltage reference will be used and the voltage of the power supply drops the measured result will be falsified. It's powered from a li-ion battery from an old phone.
The program is written in bascom to save the battery.
If the measured voltage is 0, on the LCD there will be seen only a dot. If the input voltage is below 10V, also the leading 0 isn't displayed.
If the powering voltage drops under 3V, the processors go to powerdown mode.
The program takes 40% of memory.
The two buttons are for switching the device on and off .
Link to original thread – Woltomierz na Atmega8