I want to design a voltmeter with minimum no of components so the pcb becomes as small as possible.For this purpose i wish to direct drive the seven segment display.
Considering the fact Typically for a standard red coloured 7-segment display, each LED segment can draw about 15 mA to illuminated correctly, so on a 5 volt digital logic circuit, the value of the current limiting resistor would be about 200Ω (5v – 2v)/15mA, or 220Ω to the nearest higher preferred value.
if I am going to use PIC16f676 ,The data sheet says PORTA & PORTC Can Source & Sink 200mA combined ,with maximum source /sink per pin 25mA
How will i calculate source/sinking current for a seven segment display working in a multiplexed environment( say 4 seven segments ) ??