Circuit Documentation

Summary

This circuit is designed to interface an ESP32 microcontroller with various input and output components, including momentary push buttons, a rocker switch, an LED, an OLED display, and a power management system. The ESP32 is programmed to handle Bluetooth communication, display information on the OLED screen, and read battery voltage levels.

Component List

1. Rocker Switch (4 Pin)

   • Pins: 1, 2, 3, 4
   • Description: A 4-pin rocker switch used to control power to the circuit.

2. LED (Blue, Two Pin)

   • Pins: Cathode, Anode
   • Description: A blue LED used for visual indication.

3. Momentary Push Button Switch

   • Pins: 1, 2, 3, 4
   • Description: A 4-pin momentary push button switch used for user input.

4. 18650 Battery in Holder

   • Pins: GND, VCC
   • Description: A 18650 battery holder providing power to the circuit.

5. USB Type C Power Delivery Dummy Breakout

   • Pins: SDA, SCL, V+, Vout, GND, Data -, Data +
   • Description: A USB Type C breakout board for power delivery and I2C communication.

6. Power Cell - LiPo Charger/Booster

   • Pins: JST -, JST +, VCC, GND, 5V, PS, EN
   • Description: A LiPo charger and booster module for managing battery power.

7. Pushbutton

   • Pins: Pin 1, Pin 2, Pin 3, Pin 4
   • Description: A 4-pin pushbutton used for user input.

8. ESP32-WROOM

   • Pins: 3V3, EN, SP, SN, 34, 35, 32, 33, 25, 26, 27, 14, 12, GND, 13, 23, 22, TX0, RX0, 21, 19, 18, 5, 17, 16, 4, 0, 2, 15, SD1, SD0, CLK, 5V, CMD, SD3, SD2, USB
   • Description: A versatile microcontroller with built-in Wi-Fi and Bluetooth capabilities.

9. OLED 128x64 I2C Monochrome Display

   • Pins: VDD, GND, SCK, SDA
   • Description: A monochrome OLED display for visual output.

10. Resistor (10k Ohms)

    • Pins: pin1, pin2
    • Description: A 10k Ohm resistor used in the voltage divider circuit.

11. Resistor (20k Ohms)

    • Pins: pin1, pin2
    • Description: A 20k Ohm resistor used in the voltage divider circuit.

Wiring Details

Rocker Switch (4 Pin)

• Pin 2: Connected to VCC of the Power Cell - LiPo Charger/Booster.
• Pin 4: Connected to 5V of the ESP32-WROOM and VDD of the OLED Display.

LED (Blue, Two Pin)

• Cathode: Connected to GND of the ESP32-WROOM.
• Anode: Connected to Pin 2 of the ESP32-WROOM.

Momentary Push Button Switch

• Instance 1

  • Pin 1: Connected to Pin 3 of another Momentary Push Button Switch.
  • Pin 4: Connected to Pin 32 of the ESP32-WROOM.

• Instance 2

  • Pin 1: Connected to Pin 3 of another Momentary Push Button Switch.
  • Pin 4: Connected to Pin 33 of the ESP32-WROOM.

• Instance 3

  • Pin 1: Connected to Pin 3 of another Momentary Push Button Switch.
  • Pin 4: Connected to Pin 25 of the ESP32-WROOM.

• Instance 4

  • Pin 1: Connected to Pin 3 of another Momentary Push Button Switch.
  • Pin 4: Connected to Pin 26 of the ESP32-WROOM.

18650 Battery in Holder

• GND: Connected to JST - of the Power Cell - LiPo Charger/Booster.
• VCC: Connected to JST + of the Power Cell - LiPo Charger/Booster.

USB Type C Power Delivery Dummy Breakout

• GND: Connected to GND of the Power Cell - LiPo Charger/Booster.
• V+: Connected to PS of the Power Cell - LiPo Charger/Booster.
• Vout: Connected to 5V of the Power Cell - LiPo Charger/Booster.

Power Cell - LiPo Charger/Booster

• GND: Connected to GND of the USB Type C Power Delivery Dummy Breakout.
• VCC: Connected to Pin 2 of the Rocker Switch.
• JST -: Connected to GND of the 18650 Battery in Holder.
• JST +: Connected to VCC of the 18650 Battery in Holder.
• PS: Connected to V+ of the USB Type C Power Delivery Dummy Breakout.
• 5V: Connected to Vout of the USB Type C Power Delivery Dummy Breakout.

Pushbutton

• Pin 2: Connected to GND of the ESP32-WROOM.
• Pin 3: Connected to Pin 16 of the ESP32-WROOM.

ESP32-WROOM

• Pin 2: Connected to Anode of the LED.
• Pin 16: Connected to Pin 3 of the Pushbutton.
• Pin 21: Connected to SDA of the OLED Display.
• Pin 22: Connected to SCK of the OLED Display.
• Pin 25: Connected to Pin 4 of a Momentary Push Button Switch.
• Pin 26: Connected to Pin 4 of a Momentary Push Button Switch.
• Pin 32: Connected to Pin 4 of a Momentary Push Button Switch.
• Pin 33: Connected to Pin 4 of a Momentary Push Button Switch.
• Pin 34: Connected to Pin 2 of a Resistor (10k Ohms).
• GND: Connected to GND of the Power Cell - LiPo Charger/Booster, GND of the USB Type C Power Delivery Dummy Breakout, and GND of the OLED Display.

OLED 128x64 I2C Monochrome Display

• VDD: Connected to Pin 4 of the Rocker Switch.
• GND: Connected to GND of the ESP32-WROOM.
• SCK: Connected to Pin 22 of the ESP32-WROOM.
• SDA: Connected to Pin 21 of the ESP32-WROOM.

Resistor (10k Ohms)

• Pin 1: Connected to Pin 1 of a Resistor (20k Ohms).
• Pin 2: Connected to Pin 34 of the ESP32-WROOM.

Resistor (20k Ohms)

• Pin 1: Connected to Pin 1 of a Resistor (10k Ohms).
• Pin 2: Connected to GND of the Power Cell - LiPo Charger/Booster.

Code Documentation

#include <BluetoothSerial.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

BluetoothSerial SerialBT;

const int buttonPins[] = {32, 33, 25, 26};
const int pairButtonPin = 16;
const int ledPin = 2;
const int voltagePin = 34; // Pin connected to the voltage divider
const float R1 = 10000.0; // Resistor R1 value in ohms
const float R2 = 20000.0; // Resistor R2 value in ohms
const float Vref = 3.3; // Reference voltage of the ESP32 ADC

unsigned long lastDebounceTime[4] = {0, 0, 0, 0};
const unsigned long debounceDelay = 200;
unsigned long lastBlinkTime = 0;
bool isBlinking = false;
unsigned long blinkStartTime = 0;

void setup() {
  Serial.begin(115200);
  SerialBT.begin("ESP32_BT"); // Bluetooth device name
  pinMode(ledPin, OUTPUT);
  for (int i = 0; i < 4; i++) {
    pinMode(buttonPins[i], INPUT_PULLUP);
  }
  pinMode(pairButtonPin, INPUT_PULLUP);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.display();
}

void loop() {
  unsigned long currentTime = millis();