Digital to Analog Converter.

the process of taking a digital value and converting it to an analog signal of some variety.

We'll use an 8-bit DAC using a 5.00V reference as an example. The DAC outputs a voltage (which can be measured with a DVM) ranging from (usually) zero output to the reference output, and is directly proportional to the input.

0x0 = 0V output. 0xff (full scale in our example) = 5.00V output.

General form: Vout = Vref * count / 2^n. Where 2^n is the number of bits in the converter. For our example we used an 8-bit converter, so 2^8 = 256 possible combinations. Zero is a valid value, consuming one of our combinations, so the total span is 0 - 255 counts. So redoing our general equation:

Vout = 5.00V * count / 255 = 0.0196 * count.

So this means that you can output any DC value to an accuracy of roughly 20mv. Pretty useful! Higher resolution DACs give more steps which allow better resolution. For example a 12-bit DAC would give 1.22mv steps, 16 times better then the 8-bit part.