Circuit Documentation

Summary

This circuit is designed to provide haptic feedback and audio alerts for the blind using various sensors. The system uses an ultrasonic sensor for obstacle detection, a radar sensor for detecting fast-moving objects, an MPU6050 for detecting stairs or gutters, and a rain sensor for water detection. Different feedback mechanisms are used to alert the user. Additionally, the circuit includes a SIM900A module to make phone calls when a pushbutton is pressed.

Component List

1. PWM Vibration Motor Sensor Module Switch

   • Pins: Signal, Vcc, Ground
   • Description: Provides haptic feedback through vibration.

2. RCWL-0516 Microwave Radar Motion Sensor Module

   • Pins: CDS, VIN, OUT, GND, 3V3
   • Description: Detects motion using microwave radar.

3. HC-SR04 Ultrasonic Sensor

   • Pins: VCC, TRIG, ECHO, GND
   • Description: Measures distance using ultrasonic waves.

4. RAIN SENSOR

   • Pins: AO, DO, GRD, VCC
   • Description: Detects the presence of water.

5. MPU6050 Accelerometer + Gyroscope (Wokwi Compatible)

   • Pins: INT, AD0, XCL, XDA, SDA, SCL, GND, VCC
   • Description: Measures acceleration and gyroscopic data.

6. Loudspeaker

   • Pins: pin1, pin2
   • Description: Provides audio alerts.

7. Arduino NANO

   • Pins: D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, GND, D13, 3V3, AREF, A0, A1, A2, A3, A4 sda, A5 scl, A6, A7, 5V, RST, VIN, RX0, TX1, 13, 11, 12
   • Description: Microcontroller used to control the circuit.

8. Pushbutton

   • Pins: Pin 3 (out), Pin 4 (out), Pin 1 (in), Pin 2 (in)
   • Description: Used to trigger actions in the circuit.

9. SIM900A

   • Pins: GND, DB9-3 (RXD), DB9-2 (TXD), 5V, 3VR, 5VR, 3VT, 5VT, VCC, Ring, RESTART, RESET, STATUS
   • Description: GSM module used to make phone calls.

10. Resistor

    • Pins: pin1, pin2
    • Description: 10k Ohm resistor used for pull-up/pull-down.
    • Properties: Resistance: 10k Ohms

11. Piezo Sensor

    • Pins: +, -
    • Description: Detects vibrations.

12. BRIDGE - 1N4007

    • Pins: 1 INPUT, 2 INPUT, + PIN, - PIN
    • Description: Bridge rectifier.

13. 3.7v LiPo

    • Pins: +Ve, GND
    • Description: Power source.

14. Electrolytic Capacitor

    • Pins: -, +
    • Description: 0.001 Farads capacitor.
    • Properties: Capacitance: 0.001 Farads

15. MT3608

    • Pins: VOUT+, VIN+, VOUT-, VIN-
    • Description: DC-DC step-up converter.

Wiring Details

PWM Vibration Motor Sensor Module Switch

• Signal: Connected to Arduino NANO D3 and D4
• Vcc: Connected to Arduino NANO 5V
• Ground: Connected to Arduino NANO GND

RCWL-0516 Microwave Radar Motion Sensor Module

• OUT: Connected to Arduino NANO D5
• VIN: Connected to Arduino NANO 5V
• GND: Connected to Arduino NANO GND

HC-SR04 Ultrasonic Sensor

• TRIG: Connected to Arduino NANO D6
• ECHO: Connected to Arduino NANO D7
• VCC: Connected to Arduino NANO 5V
• GND: Connected to Arduino NANO GND

RAIN SENSOR

• DO: Connected to Arduino NANO D8
• AO: Connected to Arduino NANO A0
• GRD: Connected to Arduino NANO GND
• VCC: Connected to Arduino NANO 5V

MPU6050 Accelerometer + Gyroscope (Wokwi Compatible)

• SDA: Connected to Arduino NANO A4 sda
• SCL: Connected to Arduino NANO A5 scl
• VCC: Connected to Arduino NANO 5V
• GND: Connected to Arduino NANO GND

Loudspeaker

• pin1: Connected to Arduino NANO GND
• pin2: Connected to Arduino NANO D9

Pushbutton

• Pin 1 (in): Connected to Resistor pin2 and Arduino NANO D2
• Pin 3 (out): Connected to Arduino NANO GND

SIM900A

• 5V: Connected to Resistor pin1 and Arduino NANO 5V
• GND: Connected to Arduino NANO GND
• DB9-2 (TXD): Connected to Arduino NANO RX0
• DB9-3 (RXD): Connected to Arduino NANO TX1

Resistor

• pin1: Connected to SIM900A 5V and Arduino NANO 5V
• pin2: Connected to Pushbutton Pin 1 (in) and Arduino NANO D2

Piezo Sensor

• +: Connected to BRIDGE - 1N4007 1 INPUT
• -: Connected to BRIDGE - 1N4007 2 INPUT

BRIDGE - 1N4007

• 1 INPUT: Connected to Piezo Sensor +
• 2 INPUT: Connected to Piezo Sensor -
• + PIN: Connected to Electrolytic Capacitor + and MT3608 VIN+
• - PIN: Connected to Electrolytic Capacitor - and MT3608 VIN-

3.7v LiPo

• +Ve: Connected to MT3608 VOUT+
• GND: Connected to MT3608 VOUT-

Electrolytic Capacitor

• +: Connected to BRIDGE - 1N4007 + PIN and MT3608 VIN+
• -: Connected to BRIDGE - 1N4007 - PIN and MT3608 VIN-

MT3608

• VIN+: Connected to BRIDGE - 1N4007 + PIN and Electrolytic Capacitor +
• VIN-: Connected to BRIDGE - 1N4007 - PIN and Electrolytic Capacitor -
• VOUT+: Connected to 3.7v LiPo +Ve
• VOUT-: Connected to 3.7v LiPo GND

Code Documentation

Arduino NANO (Microcontroller 1)

/*
 * This Arduino sketch is designed to interface with a SIM900A module and a pushbutton.
 * When the pushbutton is pressed, the Arduino will send a command to the SIM900A
 * module to initiate a call to the phone number +91 8330899670.
 */

#define BUTTON_PIN 2
#define SIM900A_RX 0
#define SIM900A_TX 1

void setup() {
  // Initialize the button pin as an input with an internal pull-up resistor
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  // Initialize serial communication with the SIM900A module
  Serial.begin(9600);
}

void loop() {
  // Check if the button is pressed
  if (digitalRead(BUTTON_PIN) == LOW) {
    // Send the command to the SIM900A to make a call
    Serial.println("ATD+918330899670;");
    // Wait for a while to avoid multiple triggers
    delay(1000);
  }
}

Arduino NANO (Microcontroller 2)

/*
 * Haptic Navigation Shoes for the Blind
 * This Arduino sketch is designed to provide haptic feedback and audio alerts
 * for the blind using various sensors. The system uses an ultrasonic sensor
 * for obstacle detection, a radar sensor for detecting fast-moving objects,
 * an MPU6050 for detecting stairs or gutters, and a rain sensor for water
 * detection. Different feedback mechanisms are used to alert the user.
 */

#include <Wire.h>
#include <MPU6050.h>

#define ULTRASONIC_TRIG_PIN 6
#define ULTRASONIC_ECHO_PIN 7
#define RADAR_PIN 5
#define VIBRATION_MOTOR_1_PIN 3
#define VIBRATION_MOTOR_2_PIN 4
#define SPEAKER_PIN 9
#define RAIN_SENSOR_PIN A0
#define RAIN_THRESHOLD 500

MPU6050 m