“Alice opened the door and found that it led into a small passage, not much larger than a rat-hole: she knelt down and looked along the passage into the loveliest garden you ever saw”
Alice in Wonderland
Sometimes you need to know what is going on outside your door. Of course you can install a PIR sensor or HCSR04 distance sensor with cables and all but, wouldn't be cool to use an indoor Milimiter Wave Radar sensor instead? With a MM Wave Radar, you can detect persons up to 9 meters away, behind doors, walls, behind the bed also and you can even detect a stationary humans, like sleeping persons.
DFRobot has an interesting MM Wave Radar with part #SEN0395 at $29.00, what can be done with it? What about an alarm with silent Telegram Notification?
First of all, what is a milimiter Wave Radar Sensor? Is it the same as a microwave? No it is not. It has better resolution. “24GHz mm wave sensor first emits FMCW and CW radio waves to the sensing area. Next, the radio waves, reflected by all targets which are in moving, micro-moving, or extremely weak moving state in the area, are converted into electrical signals by the millimeter-wave MMIC circuit in the sensor system. After that, these signals will be sent to the processor and processed through the related signal and data algorithms. Then, the target information can be solved out. The millimeter-wave radar can sense the human presence, stationary and moving people within the detection area. Moreover, it can even detect static or stationary human presence such as a sleeping person. The sensor has a strong anti-interference ability, not to be affected by snow, haze, temperature, humidity, dust, light, noise, etc.”
How is this integrated with ESP32 and Arduino?
From electronic point of view VCC, GND and TX/RX From software side, a simple library #include
HardwareSerial mySerial(1);
DFRobot_mmWave_Radar sensor(&mySerial);
mySerial.begin(115200, SERIAL_8N1, 5, 7); //RX,TX
sensor.factoryReset();
sensor.DetRangeCfg(0, howManyMeters);
To read the sensor just use
int val = sensor.readPresenceDetection();
The returned value will be 0-false or 1-true
There are some settings you can touch in regards to latency. Instead of using the default sensor.OutputLatency(0, 0), you can use for example 200, 800: “The target is detected, the delay time is 5 seconds. The target disappears, the delay time is 20 seconds”
Code settings
int LED_BLINK = 10; // onboard led pin for Firebeetle ESP32C
int howManyMeters=2; // until 9 meters
int loopDelay=1000; // delay for looping
int alarmDelay=10000; // delay after the notification is sent to Telegram
int lastStateWasClear=1; // not a settting, but a flag
Parts
ESP32C3 https://www.dfrobot.com/product-2566.html?tracking=61357a929f73e
MM Wave Radar https://www.dfrobot.com/product-2282.html?tracking=61357a929f73e
Female to female jumper cables
USB C Power Bank
Circuit
Source code
Download mmWave Alarm source code from this link
3d printed case
Download and print these 2 parts with PLA and Support.
Arduino IDE Setup
Open Arduino IDE and click File→Preferences
Add to additional boards manager https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
Add ESP32, Install
Click Tools->Board: select ESP32C3 Dev Module (usually the first in the list)
Select USB CDC on boot enabled
Then install these 2 libraries
#include
#include
Now load the .ino fie, change your WiFi and Telegram credentials and upload to the ESP32C3
Telegram integration
In order to get those credentials for Telegram bot you need to:
Go to Telegram App, search botfather, send /start send /newbot
Go to t.me/sandoombot and get your token
Search idBot in Telegram App
Send /getId
Send a message to the bot created searching by link
Create a Group and add the bot
Load
https://api.telegram.org/botXXXXXXX:YYYYYYY/getUpdates
Extract the ID, like id: -1234567890
Test sending a message to the group with https://api.telegram.org/botXXXXXXXXX/sendMessage?chat_id=-123456789&text=WashingFinished
Where to go from here
There is an interesting sensing area feature that could be added to the code. The module configures that sensing area as 128 equal parts by default, each equal part is about 15cm. The configuration parameters are selected from 0~127, as the index of the distance value in the sensing area.
Contact
If you need a modification to this project to fit your needs, or a specific project for your electronic parts you are welcome to contact me for a quote @RoniBandini
