DC motor with encoder simulation

Hi. I am trying to simulate DC motor with encoder using microcontroller or FPGA - whatever is more suitable. I have managed to do it using AVR microcontroller using three parameters: speed, friction and power (**broken link removed**). Code is based on DC motor simulation written in Verilog (link). The main purpose of the project is to replace DC motor with encoder in printer - the code I have works most of the time - except when it doesn't - obviously my simulation isn't good enough. I need guidance to implement better simulation.

I have datasheet of the motor I'm trying to simulate (**broken link removed**). I was thinking of simulating the motor in Multisim or MATlab and then exporting the simulation in HDL, since both tools support it. Problem is, I'm not familiar with any of those tools.

How would you suggest that I model the motor in question, considering that I have the datasheet with motor parameters?

You might have to move this to the microcontroller forum to get much help.

How is it not working whenever it is not working (when using the FPGA).