Circuit Documentation

Summary

This circuit is designed to interface an Arduino Mega 2560 with an ILI9341 TFT display and multiple pushbuttons. The primary function of this circuit appears to be a voting system, where the Arduino Mega 2560 collects inputs from the pushbuttons and displays the voting results on the TFT display. The pushbuttons are likely used for voters to select their choices, and the system is capable of displaying the vote counts in real-time.

Component List

Arduino Mega 2560

• Microcontroller board based on the ATmega2560
• It has 54 digital input/output pins (of which 15 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button.

ILI9341 TFT Display

• A 2.8 inch color TFT LCD display with a 320x240 pixel resolution.
• It uses the ILI9341 driver and communicates with the microcontroller via SPI.

Pushbuttons (14 instances)

• Simple tactile pushbuttons used for user input.
• Each button has four pins: two for the button contacts and two for an optional internal pull-up or pull-down resistor.

Wiring Details

Arduino Mega 2560

• 3V3 connected to ILI9341 TFT Display LED
• 5V connected to ILI9341 TFT Display VCC
• GND connected to ILI9341 TFT Display GND and all Pushbutton Pin 1 (in)
• D7 PWM connected to Pushbutton Pin 2
• D8 PWM connected to ILI9341 TFT Display RESET
• D9 PWM connected to ILI9341 TFT Display DC/RS
• D10 PWM connected to ILI9341 TFT Display CS
• D52 connected to ILI9341 TFT Display SCK
• D51 connected to ILI9341 TFT Display SDI
• D22 - D33 connected to Pushbutton Pin 4 (out) (one button per pin)

ILI9341 TFT Display

• LED connected to Arduino Mega 2560 3V3
• VCC connected to Arduino Mega 2560 5V
• GND connected to Arduino Mega 2560 GND
• RESET connected to Arduino Mega 2560 D8 PWM
• DC/RS connected to Arduino Mega 2560 D9 PWM
• CS connected to Arduino Mega 2560 D10 PWM
• SCK connected to Arduino Mega 2560 D52
• SDI connected to Arduino Mega 2560 D51

Pushbuttons

• Pin 1 (in) connected to Arduino Mega 2560 GND
• Pin 2 connected to Arduino Mega 2560 D7 PWM (only for one specific pushbutton)
• Pin 3 (out) connected to Arduino Mega 2560 GND (common for all pushbuttons)
• Pin 4 (out) connected to Arduino Mega 2560 D22 - D33 (one button per pin)

Documented Code

#include <Adafruit_GFX.h>
#include <Adafruit_ILI9341.h>
#include <SPI.h>

// TFT display setup (connect appropriately to your setup)
#define TFT_CS     10
#define TFT_RST    9   // Or set to -1 and connect to Arduino RESET pin
#define TFT_DC     8
#define TFT_MOSI   11
#define TFT_CLK    13
#define TFT_MISO   12

Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC, TFT_RST);

const int masterButtonPin = 7;
const int voteButtons[12] = {22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33};

int voteCounts[12] = {0};  // Vote counts for each candidate
bool votingStarted = false;

const char* candidateNames[12] = {
  "Candidate A", "Candidate B", "Candidate C", "Candidate D",
  "Candidate E", "Candidate F", "Candidate G", "Candidate H",
  "Candidate I", "Candidate J", "Candidate K", "Candidate L"
};

void setup() {
  Serial.begin(9600);
  
  // Initialize TFT display
  tft.begin();
  tft.setRotation(3); // Set rotation (adjust for your layout)
  tft.fillScreen(ILI9341_BLACK);
  tft.setTextSize(2);
  tft.setTextColor(ILI9341_WHITE);
  
  // Master button and voting buttons
  pinMode(masterButtonPin, INPUT_PULLUP);
  for (int i = 0; i < 12; i++) {
    pinMode(voteButtons[i], INPUT_PULLUP);
  }

  // Initial display message
  tft.setCursor(0, 0);
  tft.println("Ready for voting");
}

void loop() {
  if (digitalRead(masterButtonPin) == LOW && !votingStarted) {
    votingStarted = true;
    tft.fillScreen(ILI9341_BLACK);
    tft.setCursor(0, 0);
    tft.println("Voting Started");
    delay(500);  // Debounce delay
  }

  if (votingStarted) {
    for (int i = 0; i < 12; i++) {
      if (digitalRead(voteButtons[i]) == LOW) {
        voteCounts[i]++;
        displayVotes();  // Update the display with vote counts
        delay(500);  // Debounce delay to prevent double counts
      }
    }
  }
}

void displayVotes() {
  tft.fillScreen(ILI9341_BLACK);  // Clear screen
  tft.setCursor(0, 0);  // Reset cursor position
  for (int i = 0; i < 12; i++) {
    tft.setCursor(0, i * 20);  // Adjust line spacing
    tft.print(candidateNames[i]);
    tft.print(": ");
    tft.println(voteCounts[i]);  // Print the vote count for each candidate
  }
}

This code is designed to run on the Arduino Mega 2560 and interfaces with the ILI9341 TFT display to show the voting results. The masterButtonPin is used to start the voting process, and the voteButtons array contains the pins connected to the voting buttons. When a button is pressed, the corresponding vote count is incremented and displayed on the screen. The displayVotes function updates the TFT display with the current vote counts for each candidate.