Preface

Vitis HLS, You can use it , use C and C++ Create and encapsulate a IP nucleus , from Vivado 2021 The version of started built-in , Used in substitution Vivado HLS, Because it's too new , There are few online tutorials （2020 Version or Vivado HLS）, So this series of articles , Used to record how to use Vitis HLS.

Use Vitis HLS When developing , It's best not to use C Language , It is C++, meanwhile , Use some of the things mentioned in the old tutorial "ap_cint.h" The header file will report an error , For this, please refer to the following “ error 1”. So all the code in this article will use C++.

New project

Building engineering

After opening the software , Build a new project .

Set the project directory and project name .

All the way next, It asks us to add two files , Let's skip here . To the select device column .

What I use here is xc7z020clg400-2.

Click on ok, And then click finish, It's the development interface .

Edit source

In limine , We focus on the window in the upper left corner .

stay Source One column , Let's create two new source files .

Create a new one in the project directory “src” Folder is used to store code files . I'm gonna make a new one here h Header file and a cpp file . Because of the use of C++, The file name suffix is cpp.

After the new building is completed , The window will show .

Here are the codes of two files .

• led_twinkle.h

#include <ap_int.h>
void led_twinkle(ap_int<1> *led);

• led_twinkle.cpp

#include "led_twinkle.h"

#define DELAY_TIME 50000000
#define DELAY_TIME_HALF 25000000 //optimize
//50000000

void led_twinkle(ap_int<1> *led){
    
	int i;
	for(i = 0;i < DELAY_TIME;i++){
    
		if(i < DELAY_TIME_HALF)
			*led=0;
		else
			*led=1;
	}
}

Be careful ： There are errors in the code in all the screenshots below , Please run the code listed above

Set port

stay led_twinkle.cpp Under the document , Focus on the window in the upper right corner .

Add an instruction to a function .

Follow the picture below to set . Be careful , If it is set to ap_ctrl_none, stay C/RTL An error will be reported during simulation , See error for details 4（ You can skip it, of course C/RTL Simulation ）.

Also add an instruction to the output port .

similarly , Set as shown in the figure below , Set to ap_none Will play a warning , See error for details 4（ You can also ignore , Set to ap_none）.

When it's set up , The relevant code will be automatically added to the source code , It is not recommended to add , It's best to use software to automatically generate .

Add tests

stay “Test Bench” in , Create a new source file , be called led_twinkle_test.cpp.

Source code is as follows .

• led_twinkle_test.cpp

#include "led_twinkle.h"

ap_int<1> led_1;

int main(){
    
	led_twinkle(&led_1);
	printf("Run successfully!");
	return 0;
}

Then you need to set the top-level function .

Select the function just set .

Verification test

To generate correctly IP nucleus , The following four tests must pass .

C Language simulation

function C Language simulation .

In addition to its own grammatical errors, it will report errors , If I use theta C Written language , Instead of C++, Errors will also be reported here , See the mistake 1.printf Code results , It will show here , and C The language console is the same , Output some test information written by yourself .

C Language synthesis

function C Language synthesis .

If the latest patch is not installed , An error may be reported here , See the mistake 2. And if the port setting is wrong , There will be errors 4. After the simulation, the interface information and other related information will be .

C/RTL Simulation

function C/RTL Simulation .

Follow the following settings .

After that, the result will appear . If you set the function to ap_ctrl_none, Will report a mistake , See error for details 4（ You can skip it, of course C/RTL Simulation ）.

export RTL

Run export RTL.

The default can be , You don't need to set the output directory .

You will be prompted that the export was successful .

IP The kernel is generated in the default directory .

final result

Generated IP Nuclear can be in Vivado Shows . Verification and testing will be put into the next article .

If the function and port are set separately "ap_ctrl_none" and "ap_none", It's like this . Verify in the next article IP The core article will use the IP nucleus .

Error collection

error 1

unexpected top argument type: type of the parameter is C language  Arbitray-precesion type

I've been looking for answers for a long time , Problems found , yes <ap_cint.h> Error in this header file . from Vitis 2021 Start （Vivado 2021）, The official clearly no longer supports this header file , It is also recommended to use C++ Development . This header file is still used in the code of many old tutorials , They use C Language .

Official instructions and solutions ：

Vitis HLS：C Language support

The solution is to reference <ap_cint.h> Change it to <ap_int.h>, At the same time, the relevant data types need to be modified .

error 2

clang compile failed: child process exited abnormally

In fact, it has been prompted here , The relevant header file could not be found , But the header file is clearly included in the project .

It's actually because of the use of include When , The difference between double quotation marks and angle brackets . In this error , Incorrect use of double quotation marks to refer to .

Change to double quotation marks .

error 3

Failed to generate IP

This report is wrong . No specific information is given in the console , In fact, just install the latest patch . Refer to the link below .

Export IP Invalid Argument / Revision Number Overflow Issue (Y2K22)

Unzip the downloaded patch into the software directory , Hold down Shift Key and then press the right mouse button , Open console .

Input README The code given in .

Running results . Patch installed successfully , Just restart the software .

error 4

A warning

WARNING: [RTGEN 206-101] Port 'led' with mode 'ap_none' may require an associated data valid signal to correctly communicate with other blocks or a test bench; automatic C/RTL co-simulation may not be able to verify such a port.

There is an error

ERROR: [COSIM 212-4] *** C/RTL co-simulation finished: FAIL ***  

A similar error occurred , It's all because of the port setting error . In many old tutorials , When it comes to setting the function to "ap_ctrl_none", And the port is set to "ap_none", But this brings uncertainty . The correct way is to set it to "ap_ctrl_hs" as well as "ap_hs", So that we don't make a mistake , The results are the same .

But set the function to "ap_ctrl_hs", That is, a two-way protocol , Will introduce a lot of IO mouth . Use "ap_ctrl_none" It's OK, too , Just need to skip C/RTL Simulation .