Altera DE2 interfacing with analog sensor
If your Altera has LVDS inputs, you've got a fairly good comparator. It's possible to make a crude Sigma-Delta (or PWM) DAC and thus get a crude ADC. It's not going to be a very good ADC- noisy and the default reference is the crummy digital supply rails and range will be limited, but if all you need is a few bits it might work for you.