Digital Voltmeter with 7 segment display on Atmel AVR- attiny13

Digital voltmeter on attiny13 with 4 digit seven segment display. 4 digit 7 segment led display connection using only 2 pin is avaliable here: http://developrog.com/index.php/categories-of-articles/temporary-unnamed-categories/item/74-attiny13-and-4-digit-7-segment-display-2-wire-connection-using-74hc595 8 digit connection led display and led_display library is here : http://developrog.com/index.php/categories-of-articles/temporary-unnamed-categories/item/75-8-digit-7-segment-led-display-only-2-wire