Pong Game - Introduction to ESP32
A fun pong game for the TTGO T-Display with sound effects. Choose your sound module:
- DFPlayer Mini — full MP3 playback from SD card, one track per event
- ISD1820 — simple record-and-play chip, one recorded sound triggered on paddle hit or score lost
The board
What You'll Learn
- How to upload code to an ESP32
- How to wire a sound module (DFPlayer Mini or ISD1820) and trigger it from code
- How software controls hardware through GPIO pins
- Serial communication between devices (DFPlayer)
- How edge-triggered signals work (ISD1820)
What You Need
Hardware
- TTGO T-Display (ESP32 with built-in screen)
- USB-C cable to connect to your computer
- Small speaker (3W 8ohm recommended)
- Jumper wires to connect things
Choose one sound module:
| Module | Pros | Cons |
|---|---|---|
| DFPlayer Mini | Different sound per event, SD card holds many tracks | Needs SD card and MP3 files |
| ISD1820 | No SD card needed, record your own voice/sound | Only one sound, no volume control |
Software
How to Play
Onboard Buttons
External Buttons (Optional)
You can add your own buttons for a better gaming experience!
- GPIO 25 - External button to move paddle LEFT
- GPIO 13 - External button to move paddle RIGHT
Wiring external buttons:
Button leg 1 -----> GPIO pin (25 or 13)
Button leg 2 -----> GND
No resistor needed - the ESP32 has internal pull-up resistors!
Gameplay
- Hit the ball with your paddle to score points!
- The ball appears to roll as it moves - watch it spin!
- If you miss, you lose a point
Getting Started
Step 1: Upload the Code
- Connect your T-Display to your computer with a USB cable
- Open this folder in VS Code
- Click the PlatformIO: Upload button (→ arrow at the bottom)
- Wait for it to finish - the game will start automatically!
Step 2: Play the Game First!
Before wiring anything, play the game to understand when events happen:
- Ball bounces off walls
- Ball hits your paddle
- You score a point
- You miss the ball
Wiring Up Sound!
Pick one sound module and follow its wiring guide below. Then set the matching option in config.h.
Option A: DFPlayer Mini
The DFPlayer Mini plays MP3 files from a micro SD card. You can assign a different sound to each game event.
Wiring
T-Display DFPlayer Mini
--------- -------------
GPIO 17 (TX) ----> RX (through 1K resistor recommended)
GPIO 21 (RX) <---- TX
GPIO 22 <---- BUSY (optional — detects when playing)
GND ----> GND
5V ----> VCC
SPK1 ----> Speaker (+)
SPK2 ----> Speaker (-)
Note: Use 5V for louder output. The 1K resistor on TX protects the DFPlayer's RX pin.
Setting Up Sound Files
- Format a micro SD card as FAT32
- Create a folder named
mp3in the root - Name your sound files:
0001.mp3,0002.mp3,0003.mp3, etc. - Insert the SD card into the DFPlayer
Recommended sound files:
| File | Event |
|---|---|
0001.mp3 |
Score milestone award (every 5 points by default) |
0002.mp3 |
Paddle hit (regular) |
0003.mp3 |
Score lost |
Enable in config.h
#define DFPLAYER_ENABLED 1 // Enable DFPlayer #define ISD1820_ENABLED 0 // Disable ISD1820
Option B: ISD1820 Voice Record Playback Module
The ISD1820 is the simplest way to add sound. It stores one recorded sound directly on the chip — no SD card, no MP3 files. Just record your voice or a sound effect by holding the REC button, and the ESP32 will trigger it during the game.
Recording Your Sound
- Power the ISD1820 (3.3V or 5V)
- Hold the REC button on the module and speak or make a sound into the microphone
- Release REC when done — the sound is saved permanently, even without power
- Press the PLAY button on the module to hear it back before wiring to the ESP32
Wiring
T-Display ISD1820
--------- -------
GPIO 15 ----> P-E (Play Edge-triggered)
GND ----> GND
3.3V or 5V ----> VCC
SP+ ----> Speaker (+)
SP- ----> Speaker (-)
Important: Connect to the P-E pin (Play Edge), NOT the P-L pin. P-E plays the sound once when the pin goes HIGH, which is what we want.
Enable in config.h
#define DFPLAYER_ENABLED 0 // Disable DFPlayer #define ISD1820_ENABLED 1 // Enable ISD1820 #define ISD1820_TRIGGER_PADDLE_HIT 1 // Play on paddle hit (1=yes, 0=no) #define ISD1820_TRIGGER_SCORE_LOST 1 // Play on score lost (1=yes, 0=no)
No Sound Module?
That's fine too — just disable both in config.h:
#define DFPLAYER_ENABLED 0 #define ISD1820_ENABLED 0
The game runs perfectly without any sound hardware attached.
Game Events
| Event | When Does It Trigger? | DFPlayer | ISD1820 |
|---|---|---|---|
| Wall Bounce | Ball bounces off any wall | ❌ | ❌ |
| Paddle Hit | Ball hits your paddle | ✅ regular sound | ✅ (configurable) |
| Score Milestone | Score reaches a multiple of 5 | ✅ award sound | ❌ |
| Score Lost | You miss the ball | ✅ | ✅ (configurable) |
Customizing the Game
Open src/config.h to change settings:
// ---- DFPlayer ---- #define DFPLAYER_ENABLED 1 // 1 = enable, 0 = disable #define DFPLAYER_TX_PIN 17 #define DFPLAYER_RX_PIN 21 #define DFPLAYER_VOLUME 10 // 0-30 #define TRACK_AWARD 1 // 0001.mp3 - plays at score milestones #define TRACK_PADDLE_HIT 2 // 0002.mp3 - plays on regular paddle hit #define TRACK_SCORE_LOST 3 // 0003.mp3 - plays on score lost #define SCORE_MILESTONE_INTERVAL 5 // Award sound fires at 5, 10, 15, 20... // ---- ISD1820 ---- #define ISD1820_ENABLED 0 // 1 = enable, 0 = disable #define ISD1820_PLAY_PIN 15 // GPIO connected to P-E pin #define ISD1820_TRIGGER_PADDLE_HIT 1 // 1 = trigger on paddle hit #define ISD1820_TRIGGER_SCORE_LOST 1 // 1 = trigger on score lost
Other Fun Settings to Try
#define PADDLE_WIDTH 15 // Make paddle bigger = easier game #define BALL_SPEED_START 3 // Higher number = slower ball #define PADDLE_SPEED 2 // How fast paddle moves // External button pins (set to -1 to disable) #define EXT_BUTTON_DOWN 25 // External button - paddle left #define EXT_BUTTON_UP 13 // External button - paddle right
Adding Your Own Event Code! 🛠️
Want to customize what happens when game events occur? You can add your own custom code!
Where to Put Your Code
Open src/events.cpp - this is where all the event magic happens!
The file has 4 event functions you can modify:
void onWallBounce() {
// This runs when the ball hits a wall
}
void onPaddleHit() {
// This runs when you hit the ball
}
void onScoreGained() {
// This runs when you score a point
}
void onScoreLost() {
// This runs when you miss the ball
}
Project Files Overview
| File | What's Inside |
|---|---|
src/main.cpp |
The game code (paddle, ball, score) |
src/config.h |
Settings you can change (pins, speeds, sizes) |
src/events.h |
List of event functions (don't change this) |
src/events.cpp |
Your code goes here! Event implementations |
T-Display Pinout
Here are the GPIO pins used in this project:
| Pin | Usage | Notes |
|---|---|---|
| 0 | Left button | Onboard button |
| 13 | External button | Default: External LEFT button |
| 15 | ISD1820 P-E | Trigger pin (when ISD1820 enabled) |
| 17 | DFPlayer TX | Serial TX to DFPlayer RX (when DFPlayer enabled) |
| 21 | DFPlayer RX | Serial RX from DFPlayer TX (when DFPlayer enabled) |
| 22 | DFPlayer BUSY | Optional: detect when DFPlayer is playing |
| 25 | External button | Default: External RIGHT button |
| 26 | Event pin | Ball wall bounce |
| 27 | Event pin | Ball paddle hit |
| 32 | Event pin | Score gained |
| 33 | Event pin | Score lost |
| 35 | Right button | Onboard button (input only) |
Troubleshooting
No sound from DFPlayer
- Check wiring: TX to RX, RX to TX (they cross over!)
- Make sure the SD card is formatted as FAT32
- Verify sound files are in an
mp3folder and named0001.mp3,0002.mp3, etc. - Try a different speaker
- Check the DFPlayer is getting power (5V recommended for reliable operation)
- Open the Serial Monitor — the game prints
[DFPlayer] OK!or a wiring error on startup
No sound from ISD1820
- Make sure you have recorded a sound first (hold REC button, speak, release)
- Check you are connected to the P-E pin, not P-L
- Test the sound by pressing the PLAY button on the module itself
- Check
ISD1820_ENABLED 1is set inconfig.h - Verify the GPIO pin number matches
ISD1820_PLAY_PINinconfig.h
Code won't upload
- Try pressing the RESET button on the T-Display
- Make sure the USB cable supports data (some only charge)
- Try a different USB port
Game runs but no sound
- Open the Serial Monitor — startup messages show which module is active and whether it initialised successfully
Want to Learn More?
- Change the ball to a different image! (Look at
kim-jong-un.h) - Add your own background image! (Look at
background.h) - Create new events for different game situations
- Adjust the ball rotation speed in
main.cpp(BALL_ROTATION_SPEED)
Features
- 🎨 Custom ball sprite with rolling animation
- 🖼️ Background image support
- 🎮 Onboard + external button control
- 🔊 DFPlayer Mini sound effects (multiple tracks, SD card)
- 🔊 ISD1820 voice module support (record your own sound, no SD card needed)
- 📈 Increasing difficulty as you score
Have fun learning electronics! 🚀