I have a question about connecting a potentiometer to a FPGA.
I am connecting a potentiometer to an external 8 bit ADC chip that is outside the FPGA. I want the pot to represent a speed setpoint ranging from a min to max value, for example say 0 rpm to 100 rpm of a motor.
Now since I have no ALU on my FPGA, I am creating my own ALU which is no problem. However I was planning on working out the RPM setpoint based on the following equation below: $$Setpoint~RPM = ADC_{Pot} \cdot \frac{Range_{RPM}}{2^N-1}$$
For example pot is set to ~50% and motor speed range is 100rpm: 128 ( 100 / 255 ) = 50.1 RPM.
Now the problem I run into is I require floating point numbers for my calculations. Am I overcomplicating this process of converting the pot value into an RPM setpoint by using the ALU? Could this simply be done in some code in VHDL?
I would appreciate any help, thanks.
EDIT
Ok it might be useful if I provide some information about what I am doing.
So I am making my own processing core on an FPGA. I wish to display this rpm setpoint on a LCD display. So I am working in binary with registers completely. So my pot value is inputted with 8 bit digital resolution. And say I want to represent on my LCD display a value between 0 and 100 rpm. I was going to use the above calculation with my designed ALU.
So for the calculation I was going to store the (RPM Range / Bit Size) value in memory to avoid needing to divide in my ALU and ca just multiply it with the inputted pot value but this will require a decimal point which is confusing me.