Greetings, total and complete newbie here.
I'd like to build an audio level meter: series of LEDs that light up depending on the detected sound volume.
However, it's totally boring to use a ready-made chip like an LM3915.
I'm wondering if I can do something similar using an 8051.
Since an input to the 8051 is binary, I'm not sure how I could detect differences in volume. I guess a microphone is just a resistor, so depending on the volume, the voltage will change. So one idea is to put increasingly strong resistors on the input pins of the 8051, such that each pin detects a certain voltage range. I could maybe use five pins to detect five ranges of voltage, and then use another five pins as output to drive the LEDs, with code on the 8051 that says "if this pin input pin is hi, then set that output pin hi, too" or something.
Or is there a way I can detect varying voltage (volume) using only one input pin on the 8051?

Like I said, total newbie. I've got plenty of experience programming high-level (Java, etc.) but no assembly, and as you can tell my electronics understanding is less than my grasp of assembly!
Maybe this is too hard for me as a first project, but it must be doable.

Thanks,
r e n