Electronics - Quartus II - Creating your first SoPC with Qsys and Nios II software

Qsys is the new Altera SOPC Builder tool. So if you are using Quartus 13.0.x, you should have it.

Then, don't be surprised not having, for example, the simple SOPC Builder tool in your Quartus version.

It's just normal because Qsys is the new name of the SOPC Builder and its improvement.

That said, let's get started with this tutorial and let's create your first System on Programmable Chip (SoPC) or System on Chip (SoC) with Qsys.


For this tutorial, we will realize a system which lights two LEDs from two switchers.

We will use the Altera DE1 board and Quartus II 13.0sp1.
If you had the DE2, you would have only few things to change. So keep reading.

It’s not so easy to all understand first time, but at the end you will be proud to achieve this really interesting tutorial.

This project is a mix between hardware and software.

We’re indeed going to choose which parts of hardware we want, realize the design and then create a software library from this design. Then we will be able to create a program in C language in order to upload this program into the DE1 board.

For that, the design hardware will be created with Qsys and a file will be generated, that’s de1_blinker.sopcinfo.

With this file we will be able to create the BSP (Board Support Package) that it will be compiled with our user application in C language.

The user application and the BSP will be created with SBT (Software Build Tools).

These tools are composed of:

  • GCC
  • A special Nios II GNU library C
  • A HAL (Hardware Abstraction Layer)

SBT is a tool based on Eclipse, a well known open source IDE.

You don’t need to have Eclipse already installed because the Indigo version will be launched for you when you will decide to create your BSP.

Indeed a hidden Eclipse was installed with your Quartus installation.

After the compilation and the linkage of the user application and the BSP, a new file will be added: de1_blinker.elf.

At this point, we will send it to the board in order to program it.

Finally we will see the result directly on the board with red LEDs lit from switchers.

Creating a project from Quartus

We have first of all to create a new Quartus project.

From Quartus > File > New Project Wizard…

  • Project name: chip1
  • Project directory: C:\dev\fpga\altera\sys-on-prog-chip
  • Project top-level entity: chip1

Next > Next >

  • Family: Cyclone II
  • Package: FBGA
  • Pin count: 484
  • Speed grade: 7
  • Available devices: EP2C20F484C7

Next > Next > Finish

Creating an interaction between components with Qsys

From Quartus > Tools > Qsys

Qsys opens.

Click File > Save > the Save windows should open direct from the sys-on-prog-chip directory > then enter the name de1_blinker in the input text > Save.

In your project directory you can now see a new file: de1_blinker.qsys.

Let’s back to Qsys.

On the right you could see the clk_0 clock in the System Contents tab.

Let’s rename it by clock_main.

You can check all tabs to see what they contain. Everything is by default correct, so don’t modify anything.

Let’s now add a new component.

Adding a processor

From Component Library (on the left), select: Library > Embedded Processors > Nios II Processor.

Double-click it or click the +Add… button in order to add on the System Contents.

The Nios II Processor’s module window opens.

On the Core Nios II tab > Select a Nios II Core > Nios II/e > Finish

The Nios II core is added on the System Contents with the name nios2_qsys_0, let’s rename it by nios2_proc.

You can see that the data_master and instruction_master are already linked to jtag_debug_module with a black line passing by a tiny black round.

At the bottom, in the Messages tab, there are 4 errors.

Don’t be afraid, we will fix it in a few moment.

Adding a memory

Let’s continue by adding a new module: a memory.

Click Library > Memories and Memory Controllers > On-Chip > On-Chip Memory (RAM or ROM) > +Add…

The On-Chip Memory (RAM or ROM)’s module window appears and in the Size area > Total memory size you could see 4096 bytes.

This size is a bit short for our first example, so let’s replace it by 16384.

Click Finish.

The onchip_memory2_0 is added to the System Contents.

Rename it by onchip_memory.

There are now 6 errors at the bottom and 1 warning.

Adding a first PIO (for switchers)

Let’s continue by adding the PIO (Parallel I/O) module inputs:

Click Library > Peripherals > Microcontroller Peripherals > PIO (Parallel I/O) > + Add…

The PIO (Parallel I/O)’s module window appears.

In the Basic Settings > Width (1-32 bits) > there is already 8 written. Even if we need only 2 switchers, let it like that. It will allows us to show how to assign location to the pins, later.

Still from the Basic Settings tab > Direction > select Input > Finish.

The PIO (Parallel I/O) module input has just been added to the System Contents.

Rename it from pio_0 to switcher.

Now there are 8 errors and 2 warnings.

Adding a second PIO (for LEDs)

Let’s continue by adding the second PIO (Parallel I/O) module outputs:

Click Library > Peripherals > Microcontroller Peripherals > PIO (Parallel I/O) > + Add…

The PIO (Parallel I/O)’s module window appears.

In the Basic Settings tab > Width (1-32 bits) > there is already 8 written. This time change it by 2.

Still from Basic Settings tab > Direction > select Output > Finish.

The PIO (Parallel I/O) module output has just been added to the System Contents.

Rename it from pio_0 to led.

Now there are 10 errors and 3 warnings.

Adding a system ID peripheral

It’s time to add the final module: the System ID Peripheral.

This module acts as a manager between hardware and the BSP.

Click Library > Peripherals > Debug and Performance > System ID Peripheral > + Add…

The System ID Peripheral’s module window appears.

In Parameters > 32 bit System ID > change 0x00000000 by 1337 (it will be automatically transformed into 0x00001337).

This number is arbitrary and must be unique.

Click Finish.

The System ID Peripheral’s module has just been added to the System Contents.

Rename it from sysid_qsys_0 to sysid_1337.

There are now 12 errors and 6 warnings.

Correcting errors, part 1

Let’s correct these errors and warnings.

First of all, let’s connect all the clocks together.

For that it’s necessary to click rounds in front of each clock, that’s:

  • nios2_proc > clk
  • onchip_memory > clk1
  • switcher > clk
  • led > clk
  • sysid_1337 > clk

Errors are reduced to 7 and warnings are still 6.

The clock_main.clk_reset output must also be assigned to other modules reset_n inputs.

For that, let’s connect them all.

Let’s connect clock_main.clk_reset to

  • nios2_proc > reset_n
  • onchip_memory > reset1
  • switcher > reset
  • led > reset
  • sysid_1337 > reset

Errors are decreased to 2 and warnings are still 6.

Correcting errors, part 2

Let’s now connect Avalon Memories together.

Let’s click the following rounds in order to connect nios2_proc.data_master  to:

  • nios2_proc > jtag_debug_module
  • onchip_memory > s1
  • switcher > s1
  • led > s1
  • sysid_1337 > control_slave

Then click the following rounds in order to connect nios2_proc.instruction_master to:

  • nios2_proc > jtag_debug_module
  • onchip_memory > s1

There are now 10 errors and 2 warnings.

Let’s assign base addresses.

From Qsys > System > Assign Base Addresses

Errors: 2.
Warnings: 2.

Let’s reopen the nios2_proc module window by double-clicking it.

In Reset Vector > Reset vector memory > select onchip_memory.s1.

In Exception Vector > Exception vector memory > select onchip_memory.s1.

Click Finish.

Then we must connect the clock_main.clk_in_reset to:

  • nios2_proc > reset_n

Correcting errors, part 3

To finish the system, we have to add connections to external connections.

As you can see the switcher.external_connection is in a not defined state.

To solve it let’s double-click in the Export column for the switcher > external_connection (Conduit).

The new Export becomes switcher_external_connection.

Do the same for the led > external_connection in the Export column.

The new Export becomes led_external_connection.

Errors: 0.
Warnings: 0.

We are done for the clicking black rounds part.

Generating HDL code

Let’s generate the Verilog HDL code.

From Qsys > select the Generation tab on the right, then click Generate at the bottom.

The Generate window appears with plenty of generating lines.

At the end of the generation, if you check your sys-on-prog-chip directory, you should see a new de1_blinker folder and 5 new files in addition to de1_blinker.sys:

  • de1_blinker.bsf
  • de1_blinker.cmp
  • de1_blinker.html
  • de1_blinker.sopcinfo
  • de1_blinker.generation.rpt

Inside the de1_blinker folder there is another folder called synthetis.

Inside the synthetis folder another called submodules with a lot of files.

Let’s back to Quartus.

Adding files, compilation and upload from Quartus

Adding files

From Quartus > Project > Add/Remove Files in Project… > the Settings window appears.

Click the ”” button at the right of the File name text input.

Select the file that you can find there:

Then click Add on the right.

The de1_blinker.v file is added.

Let’s continue by adding all other files.

Click the ”…” button at the right of the File name text input.

Select all 36 files in the following directory:

They are all added immediately (don’t need here to click Add).

Click OK.

In the Project Navigator click the Files tab.

In the list of files, select de1_blinker/synthesis/de1_blinker.v.

Right click > Set as Top-Level Entity.


Let’s start a first compilation.

From Quartus > Processing > Start Compilation.

Normally the compilation ends with no errors (only warnings).

This first compilation was to tell Quartus which pins we would like to use.

Let’s now assign correct pins with correct location.

From Quartus > Assignments > Pin Planner.

At the bottom, in the All Pins area, you should see Node Name but without their Location nor their I/O Bank and VREF Group.

To resolve this, we have to open the DE1_pin_assignments.csv, normally provided by Altera.

Notice that this assignments is only for the DE1 board. For the another board use the specific pin assignments CSV file.

Inside we can see that the CLOCK_50’s location is PIN_L1.

We have to add each location to each node.

So, in the Pin Planner, double-click the Location of clk_clk > select PIN_L1.

Automatically the I/O Bank and the VREF Group are added.

Notice: SW2 to SW7 are not used for this tutorial, so you don't have to assign them if you don't want to.

Let’s do the same for other nodes:

  • clk_clk                                                                       → PIN_L1
  • led_external_connection_export[1]             → PIN_R19
  • led_external_connection_export[0]            → PIN_R20
  • switcher_external_connection_export[7] → PIN_M2
  • switcher_external_connection_export[6] → PIN_U11
  • switcher_external_connection_export[5] → PIN_U12
  • switcher_external_connection_export[4] → PIN_W12
  • switcher_external_connection_export[3] → PIN_V12
  • switcher_external_connection_export[2] → PIN_M22
  • switcher_external_connection_export[1] → PIN_L21
  • switcher_external_connection_export[0] → PIN_L22

Once done, let's recompile the project.

From Quartus > Processing > Start Compilation.

This second compilation is really important, don't skip it.

Sending the design into the board

At this point, we have to send the file chip1.sof, generated by the second compilation, into the board.

This file can be found there:

For that, from Quartus > Tools > Programmer.

Normally you just have to click Start to upload the program into the board.

But if the output_files/chip1.sof is not visible on the right, click Add File… and choose it.

Creating a BSP library and a user application with the Nios II Software tools

The BSP library


It's necessary to have the board plugged and turned on.
Otherwise the BSP library won't find the corresponding ID nor the timestamp of the current program.
Indeed, when you create the BSP, the library will read the ID and timestamp of the board's program (in our case 0x1337 for the ID).

Once the design is sent to the board, we can create our BSP library.

From Quartus > Tools > Nios II Software Build Tools For Eclipse.

Eclipse Indigo launches then choose a workspace, for example:

From Eclipse > File > New > Nios II Application and BSP from Template.

The Nios II Application and BSP from Template window appears.

In SOPC Information File name go to choose:

Automatically in the CPU name part you can see nios2_proc appears in the drop-down menu.

Add a name in the Project name part, for example blinker-lib.

In the Project template, let Hello World as template.

Click Next, you should see blinker-lib_bsp as BSP Project name.

Click Finish.

The compilation of the BSP library starts and you can find two new projects there:

In the Project Explorer, there is then two new projects:

  • blinker-lib
  • blinker-lib_bsp

Let’s remove blinker-lib or just close it because we don’t need it at all.

A user application

It’s time now to create a user application.

From Eclipse > File > New > Nios II Application.

Let’s add a name in the Project name, for example app-to-board.

Then in the BSP location, choose blinker-lib_bsp.

Click Finish.

Let’s now create a C file.

From the Project Explorer > right-click app-to-board > New > Source File.

As Source file, type main.c.

As Template, choose Default C source template.

Click Finish.

In the new file created, write the following code that we are going to explain soon:

#include "io.h"
#include "system.h"

 * Gets led_pattern as parameter in order to write to the register.
void set_led(unsigned char led_pattern) {
    IOWR(LED_BASE, 0, led_pattern);               // writes register

 * Main, what else?
 * Gets LEDs pattern from switchers.
 * Sets LEDs register according to the pattern.
void main() {
    unsigned char led_pattern = 0x00;

    while (1) {                                   // infinite loop
        led_pattern = IORD(SWITCHER_BASE, 0);     // gets LEDs
        set_led(led_pattern);                     // sets LEDs

Then from the Project Explorer > right-click app-to-board > Run As > 3 Nios II Hardware.

The main program start compiling then it has linked.

It’s possible that the Run Configuration window opens.

Often there is a lack of information, so in the Target Connection tab, you have to click Refresh Connections on the right.

If you clik the System ID Properties… you should see expected ID base, system and timestamp.

Sometimes, there are errors because Eclipse or the board cannot retrieve correct informations (for example because the board wasn't turned on during the BSP creation).

In this case, check Ignore mismatched system ID and/or Ignore mismatched system timestamp in the Target Connection tab at the bottom.

Then click Apply and Run.

Even sometimes if you close and reopen Eclipse it works. Or if you relanch a compilation from your design from Quartus and reload the chip1.sof into the board. Or just try to recompile the project.

It’s not always easy to understand, I agree, but electronics is a delicate thing.

At the end of the process, you should see in the console, something like that:

Using cable "USB-Blaster [USB-0]", device 1, instance 0x00
Pausing target processor: not responding.
Resetting and trying again: OK
Reading System ID at address 0x00009020: verified
Initializing CPU cache (if present)

Downloading 00004000 ( 0%)
Downloading 00004F0C (61%)
Downloaded 4KB in 0.0s        

Verifying 00004000 ( 0%)
Verifying 00004F0C (61%)
Verified OK                         
Starting processor at address 0x00004020

If yes, then the program is into the board.

Try to push switchers SW0 and SW1 to high, you should see LEDR0 and LEDR1 light respectively.

Explaining the code

IORD() is a define that can be found in the io.h file.
The first argument is the base, that we already created with Qsys.
Indeed the SWITCHER_BASE is a define that can be found in the system.h file.
With this base, we know which switcher is low or high.

IOWR() is also a define that can be found in the io.h file.
We specify the LED_BASE as first parameter, it can be found in the system.h file as well.
The second parameter is the offset register number (let it at 0).
The third parameter is the LEDs that we want to light.

So if we type:

  • IOWR(LED_BASE, 0, 0) → no one will be lit
  • IOWR(LED_BASE, 0, 1) → one will be lit (the LEDR0)
  • IOWR(LED_BASE, 0, 2) → one will be lit (the LEDR1)
  • IOWR(LED_BASE, 0, 3) → both will be lit (the LEDR0 and LEDR1)


Because in binary:

  • 0 = 0000
  • 1 = 0001
  • 2 = 0010
  • 3 = 0011

Each time there is a 1, a LED is lit.

Hence with 11, both LEDs are lit.

And according to our switchers, if:

  • SW0 is high, led_pattern is equal to 1 in decimal and 0000 0001 in binary.
  • SW1 is high, led_pattern is equal to 2 in decimal and 0000 0010 in binary.
  • SW0 and SW1 are high, led_pattern is equal to 3 in decimal and 0000 0011 in binary.


A huge step has been made.

You have successfully realized a system on programmable chip.

That means you successively used Qsys to realize interaction of hardware components and generate the HDL design, used Quartus to compile the .SOF file in order to upload it into the board with the Programmer tool.

After that you have generated a BSP library to combine with a user application so that create an .ELF file and upload it into the board.

All that to light and turn off two LEDs with two switchers.

It can be a long way to achieve a tiny result, but it’s instead a giant step in your FPGA comprehension.

Great job, you’ve made it. laugh



AWESOME tutorial!! I have been looking for something like this for a long time! You're step-by-step instructions are just what I need!



Fantastic step by step tutorial thank you so much.

I got my first cheap FPGA chip a week ago.
Readed tons of PDFs data sheets, verilog versus VHDL and so.
I got my first blinking led very quickly but the NIOS II part was unclear.

But it's history now :-)



Added to my favorites.
Just a question: Did you used the QuartusII subscribed version, or the Web version ?



Hello andre,

I used the Quartus II Web Edition. smiley


it doesn't work , elf file can not be created, pleeeease help


I had the same error, and this fix worked for me:
Right-click on main.c in your app-to-board project, and select "Add to NIOSII build"
Then rebuild your bsp project, then try and run your app-to-board project again.


Downloading 00004000 ( 0%)
Downloading 00004F0C (61%)
Downloaded 4KB in 0.0s

Verifying 00004000 ( 0%)
Verifying 00004F0C (61%)
Verified OK
Starting processor at address 0x00004020

dont but the when i click on switchers nothing happen !!!


It does not work!!!! Project does not have an ELF file!!!!! I tried to do what corollary said and my project was already added to NIOSII build. I have heard that this problem has to do with the version of quartus, I am using quartus II version 13.0 web edition. I will appreciate some help please.
Thanks in advance


you must reconnect the programmer


Unbelievable! This is absolutely the most spetacular Nios tutorial I ever tried.

Here are some reasons:
1) It begins from scratch, i.e., no pre-filled files are used. Evertything has to be created;
2) The patience to write every step based on each event that is occurring produces me an incredible feeling of safety to execute each one of them;
3) I executed this tutorial in an old EP2S60F672C5ES Nios Stratix II Development Kit 2004'board and, besides the .csv pin re-assignments, it was only necessary to assign the PIN_J20 to receive a '1' constant level (which I did because the switcher inputs were leaved in the default number, 8, but only two of them were used).

Thank you very much. I was stucked because my development board didn´t run new pre-filled examples.

Excellent contribution.


Thank you for this comment Jaraqui. laugh


thanks for sharing this....its help me a lot


Amazing NIOS II tutorial! Thanks al lot!!!


Not only do I have a "Project does not have an ELF file" but when I try to compile the main.c as requested, I get an error that stops my compiling as "undefined reference to `main'" error


Save the main.c file before building the project. Does away with the "project cannot find the elf file" error.


Thanks, it helped me :)


Thanks, I was very usefull, can you explain me how to boot so it can run after power off


I did everything as instructed but when i get to compilation i got errors : Error (12006): Node instance "nios2_proc_instruction_master_translator" instantiates undefined entity "de2_blinker_nios2_proc_instruction_master_translator"
no idea how to fix it....


Hi, I'm really enjoying your tutorial; just one little thing that I can't seem to get over; when I compile I get the "top-level entity" not defined. I can't seem to find any module there (.v or .vhd) that contains "ENTITY chip1 IS" to verify. Is possible to have access to some of your source files so I can dig through? So much I'm trying to glean from your wisdom. Thanks!


Solved! On my version of Quartus 13.1, the "best" way to set the proper module as top-level entity:
Project ->set a top-level entity

No idea why my version is so different from yours, but it works! Thanks for slamming my little brain forward!


Works perfectly. But can you please tell me why we specifically used "1337" in system ID?


Hello Hafiz,

"This number is arbitrary and must be unique."

So you can write what you want to replace it. cool



Thanks for this tutorial that is very useful.

I have the same board (EP2C20F484C7) and is in this exact confiugration. Now, i would like to use SD Card to read a file but the onchip memory does not have enough memory while compiling in Eclipse (error get while including few librarys).
So I tried to change the onchip memory value in Qsys (16 384) and I didn't find how to set value to use the maximum memory available. After lot of tries, I get in Quartus :

Error (170040): Can't place all RAM cells in design
Info (170034): Selected device has 52 memory locations of type M4K. The current design requires 53 memory locations of type M4K to successfully fit.
Info (170033): Memory usage required for the design in the current device: 102% M4K memory block locations required

Could you please provide me more information about it ?
Do you confirm that the "on chip memory" is only to upload the main program file (coded in c) ?



Works perfectly, in a cheap development board based on Cyclone IV. Thanks a lot.

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