Circuit Documentation

Summary

This circuit is designed to read the battery voltage connected to pin D34 of an ESP32 microcontroller and display the value on a 0.96" OLED display connected via I2C. The circuit also includes a battery indicator. The power is supplied by a 2000mAh battery, and the voltage is regulated using a TP4056 and MT3608 modules. A touch sensor is also included in the circuit.

Component List

1. Resistor

   • Description: 100k Ohm resistor
   • Pins: pin1, pin2
   • Properties: Resistance: 100k Ohms

2. 2000mAh Battery

   • Description: Rechargeable battery
   • Pins: VCC, GND

3. TP4056

   • Description: Lithium battery charger module
   • Pins: OUT-, B-, B+, OUT+, IN-, IN+

4. MT3608

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

5. Touch Sensor TTP233

   • Description: Capacitive touch sensor
   • Pins: GND, I/O, VCC

6. ESP 32 DEVKIT V1 (30 pins)

   • Description: Microcontroller with WiFi and Bluetooth
   • Pins: EN, VP, VN, D34, D35, D32, D33, D25, D26, D27, D14, D12, D13, GND, VIN, 3V3, D15, D2, D4, RX2, TX2, D5, D18, D19, D21, RX0, TX0, D22, D23

7. 0.96" OLED

   • Description: OLED display module
   • Pins: GND, VDD, SCK, SDA

Wiring Details

Resistor 1

• Pin1 is connected to Pin2 of Resistor 2 and D34 of ESP32.
• Pin2 is connected to GND of the 2000mAh Battery and B- of TP4056.

Resistor 2

• Pin1 is connected to VCC of the 2000mAh Battery and B+ of TP4056.
• Pin2 is connected to Pin1 of Resistor 1 and D34 of ESP32.

2000mAh Battery

• VCC is connected to Pin1 of Resistor 2 and B+ of TP4056.
• GND is connected to Pin2 of Resistor 1 and B- of TP4056.

TP4056

• B+ is connected to VCC of the 2000mAh Battery and Pin1 of Resistor 2.
• B- is connected to GND of the 2000mAh Battery and Pin2 of Resistor 1.
• OUT+ is connected to VIN+ of MT3608.
• OUT- is connected to VIN- of MT3608.

MT3608

• VIN+ is connected to OUT+ of TP4056.
• VIN- is connected to OUT- of TP4056.
• VOUT+ is connected to VCC of Touch Sensor TTP233.
• VOUT- is connected to GND of Touch Sensor TTP233 and GND of ESP32.

Touch Sensor TTP233

• GND is connected to VOUT- of MT3608 and GND of ESP32.
• I/O is connected to VIN of ESP32.
• VCC is connected to VOUT+ of MT3608.

ESP 32 DEVKIT V1 (30 pins)

• D34 is connected to Pin1 of Resistor 1 and Pin2 of Resistor 2.
• GND is connected to VOUT- of MT3608 and GND of Touch Sensor TTP233.
• VIN is connected to I/O of Touch Sensor TTP233.
• 3V3 is connected to VDD of 0.96" OLED.
• D21 is connected to SDA of 0.96" OLED.
• D22 is connected to SCK of 0.96" OLED.

0.96" OLED

• VDD is connected to 3V3 of ESP32.
• GND is connected to GND of ESP32.
• SDA is connected to D21 of ESP32.
• SCK is connected to D22 of ESP32.

Code Documentation

/*
 * This Arduino Sketch reads the battery voltage connected to pin D34 of the ESP32
 * and displays the value on a 0.96" OLED display connected via I2C (SCK: D22, SDA: D21).
 * It also includes a battery indicator.
 */

#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);

void setup() {
  // Initialize serial communication at 115200 baud rate
  Serial.begin(115200);
  // Initialize the OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.display();
  delay(2000);
  display.clearDisplay();
}

void loop() {
  // Read the analog value from pin D34
  int analogValue = analogRead(34);
  // Convert the analog value to voltage (assuming 3.3V reference)
  float voltage = analogValue * (3.3 / 4095.0);
  // Print the voltage to the serial monitor
  Serial.print("Battery Voltage: ");
  Serial.print(voltage);
  Serial.println(" V");
  // Display the voltage on the OLED
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 10);
  display.print("Battery Voltage: ");
  display.print(voltage);
  display.println(" V");
  // Draw battery indicator
  int batteryLevel = map(voltage, 3.0, 4.2, 0, 100);
  display.drawRect(0, 30, 100, 10, SSD1306_WHITE);
  display.fillRect(0, 30, batteryLevel, 10, SSD1306_WHITE);
  display.display();
  // Wait for a second before the next reading
  delay(1000);
}

This code initializes the OLED display and reads the battery voltage from pin D34 of the ESP32. The voltage is then displayed on the OLED along with a battery level indicator. The voltage is also printed to the serial monitor for debugging purposes.