CE433 2022 Spring
Week 8
John Hitti
jdhitti@fortlewis.edu

Week 8

Introduction
In this week's project we will be exploring the softCore capabilities of the FPGA. We will be using PicoBlaze, a softprocessor from Xilinx, and programming simple instructions using assembly.
Task 1
In this task we will start by initializing the FPGA to run the softprocessor and use a simple program to turn on an led when a switch is flipped. We start by copying over the proper code from Xilinx and placing it in our project folder. Then we can connect the processor to the proper i/o on our FPGA.


Then we can create our assembly code.


We can then run the program to generate a ROM file from the assembly code. Once this is done, we can load it into Vivado and upload it to the FPGA bard as usual to verify the functionality.



Task 2
In this task we will now create a simple assembly program to output 13 to the leds of the FPGA. Using the same main code and process as the previous task we can upload our new assembly code to the FPGA!





Task 3
In this task we will use the MASK fuction in assembly. This function can force bits to wither zero or one. In this case we will force the bottom two bits to be one and light up the leds regardless of the input switch position.






Task 4
In this task we we will reuse the code from task one but we will shift the input to the right by one bit.





Task 5
In this task we will create a program to demonstrate the jump, load, and return instructions. When the switch is zero the output will show 5. When a switch is pressed the output will show 6. This is done by jumping between two different sections that change the output of the code.






Task 6
In this task we will create a program that will work with multiple subroutines. When the counter reduces by one the LED will increment by one.






Task 7
In this task we will revise the above code using the compare statements to achieve the same outcome.




Task 8
In this task we will create our own assembly program that will take the input (in the form of switches flipped) and sum the amount of bits in the input and return a binary value as the output (in the form of led output).






Discussion
This project was an excellent introduction into softprocessors and more specifically their implementation with FPGA devices. Xilinx's PicoBlaze processor is very useful and unlocks a lot more potential for FPGA devices.