Kid's Eye Safe Smart TV - Part 1

Outside of home COVID-19. Inside at home COVID-16. Whole world is fighting against COVID-19. But for COVID-16, I am all alone. I am tired of saying "please stay away from the screen". So thought of this concept project to avoid brain infection at home.

By the way, I call two of my kids (age 1 and 6) as COVID-16 as they are equally out of control.

Project Concept

Circuit built using microcontroller (ESP32) and ultrasonic distance censor (HC-SR04) will detect the distance of the nearest obstacle. If the measured distance is less than the preconfigured threshold (say 1 meter), microcontroller will call smart TV API (e.g. in my case Roku TV API to toggle Play/Pause  http://$ROKU_DEV_TARGET:8060/keypress/play) to perform the desired activity.

Note:  For my  Roku TV, API is there to trigger different remote button functions.

Tools,Technologies and Components used in this article

• Thonny, Python IDE for beginners
• MicroPython Firmware on the ESP32
• Roku TV External Control Protocol (ECP)
• MicroPython Libraries:
  • Ultrasonic sensor HC-SR04 driver
  • SSD1306 128x64 OLED display driver
  • WiFi Manager
• Hardware Components:
  • ESP-WROOM-32 Dev Kit
  • HC-SR04 Ultrasonic Sensor
  • Oled display 128x64 - Optional
  • Breadboard
  • 3.3v & 5v Breadboard Power Supply
  • Breadboard Jumper Wires
  • 1kΩ & 470Ω Resistors
  • Less Smart TV (Roku)

Build the Circuit

Connect all the components as shown in the diagram below.

Schematic Diagram:

Circuit Design:

Code

1. Connect ESP32 development board to your computer.
2. Open Thonny Python IDE.
3. Select Run --> Select interpreter...
4. Choose MicroPython (ESP32) as device and corresponding port.

   

5. Upload following python libraries
   • HC-SR04 driver - hcsr04.py
   • SSD1306 OLED driver - ssd1306.py
   • WiFi Manager - wifimgr.py
6. Upload the below "main.py" (vanilla version). Feel free to update as per your requirement. For my Roku TV Rest endpoint to simulate "Play/Pause" remote button is http://192.168.0.11:8060/keypress/play
   Roku keypress commands: 'home', 'rev', 'fwd', 'play', 'select', 'left', 'right', 'down', 'up', 'back', 'replay', 'info', 'backspace', 'enter', 'volumeDown', 'volumeUp', 'volumeMute', 'inputTuner', 'inputHDMI1', 'inputHDMI2', 'inputHDMI3', 'inputHDMI4', 'inputAV1', 'channelUp', 'channelDown'

import wifimgr
from hcsr04 import HCSR04
from machine import Pin,I2C
import ssd1306,time
import urequests

def init():
    i2c = I2C(scl=Pin(19), sda=Pin(18))
    oled = ssd1306.SSD1306_I2C(128, 64, i2c, 0x3c)
    sensor = HCSR04(trigger_pin=32, echo_pin=35, echo_timeout_us=1000000)

    return oled, sensor

def log(msg, x, y):
    oled.text(msg, x, y)
    oled.show()

def clearDisplay():
    oled.fill(0)

def toggleTvPlayPause():
    try:
        response = urequests.post("http://192.168.0.11:8060/keypress/play")
        print("API Response %s" % response.status_code)
        return response.status_code == 200
    except:
        print("Error !!!")
        log("Error !!!", 0, 40)
        return False



# Get OLED display & Distance sensor
oled, sensor = init()

# Connect to WIfi
log("Connecting...", 0, 0)
wlan = wifimgr.get_connection()
if wlan is None:
    log("No wifi !!!", 0, 20)
    print("Unable to connect to Wifi")
else:
    log("Connected :-)", 0, 20)
    wifimgr.deactivate_ap()
    print("Deactivated AP mode.")

time.sleep_ms(1000)

prevDistance = -1
isPaused = False

while True:
    currDistance = int(sensor.distance_cm())
    time.sleep_ms(250)

    if currDistance != prevDistance:
        print("Distance: %s cm, isPaused: %s" %(currDistance, isPaused))
        clearDisplay()
        log("Dist: %s cm" % currDistance,0, 0)

        prevDistance = currDistance

        if currDistance < 100:
            if not isPaused and toggleTvPlayPause():
                isPaused = True
        else:
            if isPaused and toggleTvPlayPause():
                isPaused = False

        print("TV -> %s" % ("Pause" if isPaused else "Play"))
        log("TV -> %s" % ("Pause" if isPaused else "Play"), 0, 40)

7. Don't update "boot.py" unless want to do anything specific interesting.

   

Note: I have used web based connection manager (WiFi Manager) to setup Wifi Connectivity in ESP32. This will save wifi usernamee & password in "profile.dat" (for me NETWORK_PROFILES='profile.dat' in wifimgr.py).

Demo

Due to home isolation, screen time got increased manifolds.  I was really worried. But initial version seems working for them.

Circuit In Action

Once they will figure out the trick (if they manually flip the play/pause using remote, it may work in their favour as Roku API http://192.168.0.11:8060/keypress/play only toggles the button), I may need to think about next version.

Video Demo:

Possible Extension

Following four may be good addition to enhance this project.

1. Buzzer to make noise along with "Pause" as an additional cue.
2. ESP32-CAM for face detection / recognition / emotion / gesture based action.
3. PIR motion sensor to pause or switch off TV, if nobody is watching. (Kid's Eye and Energy Safe Smart and Green TV - Part 2)
4. Post analytics in cloud and visualize kid's behaviour.

Download SrcCodes

All codes used in this post are available on Github: srccodes/smart-tv-distance-sensor.

References

• ESP32 DevKit V1 Pinout
• Ultrasonic sensor HC-SR04 datasheet
• Getting started with MicroPython on the ESP32