How to send Digital Value To Arduino

About

It is about how to send digital values to arduino. I was searching the way how to utilize arduino uno as a example of computer vision. And I could find several examples, such like face tracker and lane follower with wheels and etc.

Among many of those, I thought cvzone library and its use-case example was useful to practice computer vision handling, there is even a youtube tutorial. So, I tryied to follow how to implement and how to use it.

In that tutorial, I could learn and know the way of how computer vision technique could be used. but computer-vision logic was just operatable in separate normal PC not in arduino uno, because of lack of resources and absence of operation system on it probably. So the idea was just transimit relevant digital signals to arduino when a specific event happens which is triggered by computer vision processing.

For exampls, if the human face is detectted on camera image, I can make a logic to send positive signal(1) to arudino and it recieves the signal and use it to light up a LED lamp accourdingly. This is all the idea and concept that arduino can do.

Concept Diagram

concept of data exchange between Processing PC and the arduiono

Computer Vision Processing and Sending the signal from external PC

import cv2
from cvzone.FaceDetectionModule import FaceDetector
from cvzone.SerialModule import SerialObject

arduino = SerialObject('COM3')

cap = cv2.VideoCapture(0)
detector = FaceDetector()

while True:
    success, img = cap.read()
    img, bboxs = detector.findFaces(img)

    if bboxs:
        arduino.sendData([1,0])
    else:
        arduino.sendData([0,1])
    
    cv2.imshow("Image", img)
    kVal = cv2.waitKey(1)

    if kVal==27:
        break

FaceDetector

• FaceDetector use light weight model of mediapipe to detect real time face object.
• Capsulated in FaceDetectionModule.py file

SerialObject

• Basically it works by serial module, and it can be install by enterng pip install pyserial.
• 2 methods are provided,
  • sendData(self, data) to the serial device.
  • getData(data) from the serial device.

Recieving digital signal as input from Arduino.

// ino file
#include <cvzone.h>

SerialData serialData(2, 1); //(numOfValsRec,digitsPerValRec)
int valsRec[2]; // array of int with size numOfValsRec 

void setup() {
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);
  serialData.begin();
}

void loop() {

  serialData.Get(valsRec);
  Serial.print("1st :  ");
  Serial.println(valsRec[0]);
  Serial.print("2nd :  ");
  Serial.println(valsRec[1]);

  digitalWrite(13, valsRec[0]);
  digitalWrite(12, valsRec[1]);
  
  delay(300);
}

SerialData

• It also has 2 methods to communicate with external PC
  • void Send(int sendVals[]) : send the data to external PC
  • void Get(int* valsRec) : get the data from the PC

I’ve got noticed that there are each paired methods between the device and the PC, to enable serial communication.

Working like this 🚀

Once a face is detected, It turns green LED on. Else, Red LED on.

face detection with arduino

Reference

Computer Vision With Arduino | 2 Hour Course | OpenCV Python