Battery Level

i saw a kit that uses atmega 8 and HEF4094 shift register to display battery level that id got from ADC and uses only one pin pf mega8 also another 4094 displays Load bar graph and also uses only one pin of uc how dose it work

This checks the voltage with a voltage reference so the difference is represented on the Load bar

voltage check is performed by atmega 8 and how dose atmega 8 controls 4094 shoft register with one pin

interested in reading this?

Shift1 system for 1-wire shift registers - Shift and latch using 1 pin of controller