Circuit Documentation

Summary

This circuit is a multiwatt charger that utilizes an Arduino Nano to control and monitor the charging process. The system includes a 0.96" OLED display for visual feedback, a 4x4 membrane matrix keypad for user input, an Adafruit DS3502 digital potentiometer for voltage adjustment, and various resistors for voltage and current sensing. The circuit is powered by a 12V battery, regulated by an XL6009 voltage regulator.

Component List

1. Arduino Nano

   • Description: Microcontroller board based on the ATmega328P.
   • Pins: D1/TX, D0/RX, RESET, GND, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11/MOSI, D12/MISO, VIN, 5V, A7, A6, A5, A4, A3, A2, A1, A0, AREF, 3V3, D13/SCK

2. 0.96" OLED

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

3. XL6009 Voltage Regulator

   • Description: DC-DC step-up (boost) converter.
   • Pins: OUT +, OUT -, IN +, IN -

4. Battery 12V

   • Description: 12V power source.
   • Pins: +, -

5. Adafruit DS3502

   • Description: I2C digital potentiometer.
   • Pins: RL, RW, RH, V+, VCC, GND, SCL, SDA, A0, A1

6. 4X4 Membrane Matrix Keypad

   • Description: Keypad for user input.
   • Pins: R1, R2, R3, R4, C1, C2, C3, C4

7. Resistors

   • Description: Various resistors used for voltage and current sensing.
   • Instances:
     • 5000 Ohms
     • 7000 Ohms
     • 0.05 Ohms
     • 10000 Ohms
     • 330 Ohms
     • 470 Ohms

8. USB Power

   • Description: USB power source.
   • Pins: +, -

9. IRFZ44N

   • Description: N-channel MOSFET.
   • Pins: Gate, Drain, Source

Wiring Details

Arduino Nano

• GND: Connected to GND of 0.96" OLED, XL6009 Voltage Regulator, Adafruit DS3502, and battery 12V.
• D2: Connected to C4 of 4X4 Membrane Matrix Keypad.
• D3: Connected to C3 of 4X4 Membrane Matrix Keypad.
• D4: Connected to C2 of 4X4 Membrane Matrix Keypad.
• D5: Connected to C1 of 4X4 Membrane Matrix Keypad.
• D6: Connected to R4 of 4X4 Membrane Matrix Keypad.
• D7: Connected to R3 of 4X4 Membrane Matrix Keypad.
• D8: Connected to R2 of 4X4 Membrane Matrix Keypad.
• D9: Connected to R1 of 4X4 Membrane Matrix Keypad.
• VIN: Connected to IN + of XL6009 Voltage Regulator and + of battery 12V.
• 5V: Connected to VDD of 0.96" OLED and VCC of Adafruit DS3502.
• A5: Connected to SCK of 0.96" OLED and SCL of Adafruit DS3502.
• A4: Connected to SDA of 0.96" OLED and SDA of Adafruit DS3502.
• A3: Connected to pin1 of 5000 Ohms resistor.
• A1: Connected to pin2 of 0.05 Ohms resistor and + of USB power.
• A0: Connected to pin1 of 0.05 Ohms resistor and pin1 of 7000 Ohms resistor.
• AREF: Not connected.
• 3V3: Not connected.
• D13/SCK: Not connected.

0.96" OLED

• GND: Connected to GND of Arduino Nano, XL6009 Voltage Regulator, Adafruit DS3502, and battery 12V.
• VDD: Connected to 5V of Arduino Nano and VCC of Adafruit DS3502.
• SCK: Connected to A5 of Arduino Nano and SCL of Adafruit DS3502.
• SDA: Connected to A4 of Arduino Nano and SDA of Adafruit DS3502.

XL6009 Voltage Regulator

• OUT +: Connected to pin1 of 0.05 Ohms resistor.
• OUT -: Connected to - of USB power.
• IN +: Connected to VIN of Arduino Nano and + of battery 12V.
• IN -: Connected to GND of Arduino Nano, 0.96" OLED, Adafruit DS3502, and battery 12V.

Battery 12V

• +: Connected to IN + of XL6009 Voltage Regulator and VIN of Arduino Nano.
• -: Connected to GND of Arduino Nano, 0.96" OLED, XL6009 Voltage Regulator, and Adafruit DS3502.

Adafruit DS3502

• GND: Connected to GND of Arduino Nano, 0.96" OLED, XL6009 Voltage Regulator, and battery 12V.
• VCC: Connected to 5V of Arduino Nano and VDD of 0.96" OLED.
• SCL: Connected to A5 of Arduino Nano and SCK of 0.96" OLED.
• SDA: Connected to A4 of Arduino Nano and SDA of 0.96" OLED.

4X4 Membrane Matrix Keypad

• C4: Connected to D2 of Arduino Nano.
• C3: Connected to D3 of Arduino Nano.
• C2: Connected to D4 of Arduino Nano.
• C1: Connected to D5 of Arduino Nano.
• R4: Connected to D6 of Arduino Nano.
• R3: Connected to D7 of Arduino Nano.
• R2: Connected to D8 of Arduino Nano.
• R1: Connected to D9 of Arduino Nano.

Resistors

• 5000 Ohms: pin1 connected to A3 of Arduino Nano, pin2 connected to GND of Arduino Nano.
• 7000 Ohms: pin1 connected to A0 of Arduino Nano and pin1 of 0.05 Ohms resistor, pin2 connected to pin1 of 5000 Ohms resistor.
• 0.05 Ohms: pin1 connected to A0 of Arduino Nano and pin1 of 7000 Ohms resistor, pin2 connected to A1 of Arduino Nano and + of USB power.
• 10000 Ohms: Not connected.
• 330 Ohms: Not connected.
• 470 Ohms: Not connected.

USB Power

• +: Connected to pin2 of 0.05 Ohms resistor and A1 of Arduino Nano.
• -: Connected to OUT - of XL6009 Voltage Regulator.

IRFZ44N

• Gate: Not connected.
• Drain: Not connected.
• Source: Not connected.

Code Documentation

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Keypad.h>
#include <Adafruit_DS3502.h>

// Pin definitions
#define VOLTAGE_SENSOR_PIN A0
#define CURRENT_SENSOR_PIN A1
#define OLED_RESET -1

// OLED display dimensions
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

// Define the I2C address for the OLED display
#define SSD1306_I2C_ADDRESS 0x3C

// Keypad setup
const byte ROWS = 4; // 4 rows
const byte COLS = 4; // 4 columns
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6};
byte colPins[COLS] = {5, 4, 3, 2};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// DS3502 potentiometer
Adafruit_DS3502 pot = Adafruit_DS3502();

// OLED display
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Constants
const float VOLTAGE_DIVIDER