SETUP
Edge Impulse Project Setup
Data Collection
Impulse Design
Hardware and Software Setup
PROJECT EXECUTION
Download Tensorflow Lite file
Model & Label Conversion
Label Making
Modify, Build and Run the Project
NEXT STEPS

Published December 12, 2022 © GPL3+

Rock, Paper, Scissors with the Maaxboard RT

This project is a demo on how to deploy a vision project on the Maaxboard RT from Edge Impulse through MCUXpresso.

IntermediateFull instructions provided2 hours287

Rock, Paper, Scissors with the Maaxboard RT

Things used in this project

Hardware components

Avnet MaaXBoard RT

NXP MCU Link

Avnet 5V/3A USB Type-C Power Supply

Avnet MaaXBoard MIPI DSI Cap Touch 7-inch Display

Avnet MaaXBoard Camera Module

Software apps and online services

Edge Impulse Studio

TensorFlow

NXP MCUXpresso

Story

SETUP

Edge Impulse Project Setup

Click on the Link to Edge Impulse and login if you have an account or click the "Get Started" button to make one.
Start a new project.
Since this is an image classification project, select Images for the data type
Now that the project is set up, it's time to collect or upload image data!

1 / 4 • Login or Get Started with Edge Impulse

Data Collection

For more details on computer vision and image classification, visit Shawn Hymel's Computer Vision with Embedded Machine Learning course
There are multiple ways data can be collected in this project
Below are the two main steps

Device connection:

Select the Devices tab on the far left side of Edge Impulse
Connect to any available device, the smartphone was used in this example
Select the smartphone and scan the QR code to go to the URL
Give the smartphone permission to access the camera
Adjust the labels and category (training and testing data) settings for data collection of rock, paper, scissors, and background classes

1 / 8 • Go to the Devices tab under Dashboard

Image Augmentation:

This part of data collection involves taking existing images and augmenting them to create new data sets
The augmentation in this project just involves mirrored and rotated images
Install Atom or any software that allows you to look at and edit code in any languages (available instructions for installation on Windows, Mac, and Linux)
Install Python 3.9 and Tensorflow via terminal or command prompt

For Windows:

python -V

python -m pip install -U pip
python -m pip install -U setuptools

python -m pip install tensorflow==2.6
python -m pip install keras==2.6
python -m pip install tensorflow-estimator==2.6.0

python -m pip install onnxmltools mmdnn tensorflow-datasets tflite-model-maker
python -m pip install numpy scipy matplotlib ipython jupyter pandas sympy nose imageio
python -m pip install netron seaborn west pyserial sklearn opencv-python pillow

For Linux:

python3 -V

python3.9 -m pip install -U pip
python3.9 -m pip install -U setuptools

python3.9 -m pip install tensorflow==2.6
python3.9 -m pip install keras==2.6
python3.9 -m pip install tensorflow-estimator==2.6.0

python3.9 -m pip install onnxmltools mmdnn tensorflow-datasets tflite-model-maker
python3.9 -m pip install numpy scipy matplotlib ipython jupyter pandas sympy nose imageio
python3.9 -m pip install netron seaborn west pyserial sklearn opencv-python pillow

In the Data Acquisition tab on the far left, go to the Export data tab on the top right and click Export to download data that was collected in the previous step

1 / 2 • Go to Data Acquisition then Export data

There is a python code attached to this project in the Code section that takes already existing images in a folder and rotates/mirrors them
Download and adjust the code in Atom or any similar software (change the folder location in line 20 to the one where the exported data was downloaded from and keep the "/*.jpg" part to avoid errors when running the program)
After adjusting the program, open the terminal or command prompt on your operating system and run the python code from there

$ python3 rotateimage.py

With the new images the python script generated, go to the Data Acquisition tab on Edge Impulse, select Upload data, browse for the files, and upload them

Upload new images

Now you're ready for the Impulse Design part of the project

Impulse Design

When you click on the Impulse Design tab on the far left, select Image as the processing block and Classification(Keras) as the learning block
Click on Save Impulse and go to the Image section under Create Impulse
Without changing anything, click on Generate Features on the top left side of the Image section
Click on the green Generate Features button and the training set will get a Feature explorer 3D graph showing how the classes relate to each other
Then go to NN Classifier and click Start training to get an accuracy percentage and confusion matrix. (The overall accuracy is about 87%, which seems good enough to move on to the next step of the project)

1 / 4 • Create Impulse with Image as the processing block and Classification as the learning block

Hardware and Software Setup

To set up the Maaxboard RT and MCUXpresso software, follow Monica Houston and Jason Lambert's instructions on their Hackster project, Run Practically Any Tensorflow Model on Maaxboard RT and work from the Board Setup section, all the way through Test the example code section.

PROJECT EXECUTION

Download Tensorflow Lite file

On Edge Impulse go to the Dashboard section on the far left
Scroll down to the Download block output section and download the int8 quantized file of your NN Classifier model
Change the.lite to.tflite

1 / 3 • Dashboard

Model & Label Conversion

In this step you will use the the xxd utility in the terminal or command prompt to convert the.tflite file into a C array that will go into the MCUXpresso project

If using Windows or Linux:

xxd -i ei-embeddedcv-nn-classifier-tensorflow-lite-int8-quantized-model.tflite > model_data.h

If using Windows Powershell:

xxd -i ei-embeddedcv-nn-classifier-tensorflow-lite-int8-quantized-model.tflite | out-file -encoding ASCII ei-embeddedcv-nn-classifier-tensorflow-lite-int8-quantized-model.h

Open the model_data.h file and add the changes below to the top of the file:

#include <cmsis_compiler.h>

#define MODEL_NAME "ei_embeddedcv_nn_classifier_tensorflow_lite_int8_quantized_model"

#define MODEL_INPUT_MEAN 127.5f

#define MODEL_INPUT_STD 127.5f

const char model_data[] __ALIGNED(16) = {

The adjusted file should look like this:

model_data.h file

Label Making

Open a notepad, Atom, or any other code/text editor
This label is to make a file that works with C++
This file will have a list of the different classes that will be identified
Since it's rock, paper, scissors:

const char* labels[] = {
	"rock", 
	"paper", 
	"scissors", 
	"background"
};

Copy & paste the list above, make any necessary changes depending on what is being classified and save the file as labels.h

Modify, Build and Run the Project

Go back to Monica and Jason's Hackster project, Run Practically Any Tensorflow Model on Maaxboard RT and work only through the Import the model and labels files to MCUXpresso section. After that, refer to the eIQ™ Inference with Tensorflow Lite for Microcontrollers oni.MXRT1170 -With Camera instructions by NXP
Double click on the model.cpp file under the “source\model” folder in the Project Explorer tab to open it
On line 27 add the following #include for the ops resolver that supports all the operands usedby this retrained model:

#include "tensorflow/lite/micro/all_ops_resolver.h"

Find model.cpp then add the #include on line 28

On lines 30 and 31, make sure there's an #include "model.h" and #include "model_data.h". It should look like the following when finished:

On line 42, change the kTensorArenaSize variable to 800000 and On line 55, change the model name to the array name to model_data

On line 73 in model.cpp, comment out the original resolver line. Then add a new line:

tflite::AllOpsResolver micro_op_resolver;

It will look like this after:

Double click on the output_postproc.cpp file under the “source\model” folder in the Project Explorer tab to open it and make sure line 13 has an #include to the labels file

Go to Project->Build Configurations->Set Active->Release. This will enablehigh compile optimizations. This will significantly decrease the inference time of TFLM projects.
On MCUXpresso build the project by clicking Build in the Quickstart Panel to make sure there aren't any errors

Click on the Terminal tab, set up a Serial terminal with a 115200 baud rate, 1 stop bit, no parity

1 / 3 • Select the Terminal tab

Debug the project by clicking on “Debug” in the Quickstart Panel.

It will ask what interface to use. Select CMSIS-DAP.
The debugger will download the firmware and open up the debug view. It may take some timeto download the firmware. Click on the Resume button to start running

On the LCD screen, you should see what the camera is pointing at.

1 / 3 • Rock

NEXT STEPS

1 / 3 • Background reading from covering the camera with hand

As you can see, the classification has some issues with accuracy and you mainly get "background" and "paper" readings
Possible causes include the Edge Impulse project needing more images to work with, poor lighting for the camera, the training and testings sets clustering different image labels, etc.
An "Improving the accuracy of the Rock, Paper, Scissors model" project will be coming soon so you can see how the image classification was better adjusted!

rotateimage.py

from PIL import Image
import glob

image_list = []

rotated_image = []
rotated_image2 = []
rotated_image3 = []
mirror_image = []

rotated_mirror_image = []
rotated_mirror_image2 = []
rotated_mirror_image3 = []


rotate = 180
rotate2 = 90
rotate3 = 270

for filename in glob.glob('/home/frank/embeddedcv-export/training/*.jpg'):
    print(filename)
    img = Image.open(filename)
    image_list.append((img,filename))

for image,filename in image_list:
    image = image.rotate(rotate, expand=True)
    image2 = image.rotate(rotate2, expand=True)
    image3 = image.rotate(rotate3, expand=True)
    image4 = image.transpose(Image.FLIP_LEFT_RIGHT)

    image5 = image4.rotate(rotate, expand=True)
    image6 = image4.rotate(rotate2, expand=True)
    image7 = image4.rotate(rotate3, expand=True)


    rotated_image.append((image,filename))
    rotated_image2.append((image2,filename))
    rotated_image3.append((image3,filename))
    mirror_image.append((image4,filename))

    rotated_mirror_image.append((image5,filename))
    rotated_mirror_image2.append((image6,filename))
    rotated_mirror_image3.append((image7,filename))


for (new,filename) in rotated_image:
    new.save('{}'.format(filename+'.rotated.jpg'))

for (new,filename) in rotated_image2:
    new.save('{}'.format(filename+'.rotated2.jpg'))

for (new,filename) in rotated_image3:
    new.save('{}'.format(filename+'.rotated3.jpg'))

for (new,filename) in mirror_image:
    new.save('{}'.format(filename+'.mirror.jpg'))

for (new,filename) in rotated_mirror_image:
    new.save('{}'.format(filename+'.rm.jpg'))

for (new,filename) in rotated_mirror_image2:
    new.save('{}'.format(filename+'.rm2.jpg'))

for (new,filename) in rotated_mirror_image3:
    new.save('{}'.format(filename+'.rm3.jpg'))