Extend IOP16 minimal example

Overview

This is a guide to extending the minimal IOP example by adding IOP16 Peripherals to the minimal design

• This is not the same as Embedding the IOP16 into another design
• This guide requires general familiarity with IOP16 16-bit I/O CPU Design
• This example does not cover porting to a different FPGA card
  • Will need to adjust I/O pin assignments if a different FPGA is used

Steps

• Start with baseline (minimal) design
• Copy/clone baseline (minimal) design
• Build baseline (minimal) design
• Copy design to new folder
• Select/add peripherals
• Create new peripherals
• Write assembly code
• Build/test

Baseline Design

Starts from IOP example

• Similar to Arduino "Blink Sketch" and uses the following resources
  • Timer Unit - 1 second timer
    • The Timer unit can be removed if not needed
    • Timer makes Blink easier
  • On-board LED

Copy/Clone Sources

• Clone the two repositories to the same directory level since relative paths are used for source files
  • IOP16 GitHub repository
  • Design a CPU GitHub repository
• Example copies files to TestBuild folder
• There are a lot of extra files in the two unzipped folders (380MB)

Alternately download ZIP files

• Alternately you can download the two ZIP files from GitHub

• Unzip these two folders into the same folder

• Rename the folders to remove the -main from the folder path

• Result

Build Minimal Design

Start by building the minimal example in Quartus II

• Open the Project file (TestIOP16B.qpf) in Quartus II
• Relative path: ..\TestBuild\IOP16\Higher_Level_Examples\TestIOP16_Minimal

• Entities in Quartus should look like

• Build FPGA (click the blue "Start Compilation arrow)

Fix ROM File Path

• Quartus does not verify the ROM file was correct
  • Could be buried in the status messages
  • Likely need to re-point to the ROM .MIF file since Quartus II sometimes "forgets"
  • Double click on the IOP_ROM file

• Hit finish
  • Check for error message

• Re-point to the ROM file
• Make sure to select .MIF file extension

Build Again / Download

• Build again
• Should be no error messages
• Result

• Download to FPGA

• User LED should be blinking

Copy Design to new folder

• Copy from folder ..\TestBuild\IOP16\Higher_Level_Examples\TestIOP16_Minimal

• Copy to folder ..\TestBuild\IOP16\Higher_Level_Examples\TestIOP16_UART_Loopback

Select Peripherals

• Pick from Supported peripherals list
• Add UART peripheral
  • Will set up UART in loopback

• Update Memory map in comments at start of TestIOP16B.vhd to add UART addresses

-- IOP16 MEMORY Map
-- 0X00      - KEY1 Pushbutton (R)
-- 0X00      - User LED (W)
-- 0x04-0x07 - Timer Unit
-- 0X08      - UART (Cmd/Stat) (r/w)
-- 0X09      - UART (Data) (r/w)

• Add UART pins to top level entity pins list

entity TestIOP16B is
  port
  (
    -- Clock and Reset
    i_clk     : in std_logic := '1';		-- Clock (50 MHz)
    i_n_reset : in std_logic := '1';		-- SW2 on FPGA the card
    -- The key and LED on the FPGA card 
    i_key1    : in std_logic := '1';		-- SW1 on the FPGA card
    o_UsrLed  : out std_logic := '1';		-- USR LED on the FPGA card
		
    rxd1      : in std_logic := '1';		-- Hardware Handshake needed
    txd1      : out std_logic;
    cts1      : in std_logic := '1';
    rts1      : out std_logic;
    ...

Create new peripherals
Write Assembly code
Test the build