BlazePod C3 is a DIY reaction light training system inspired by commercial products like BlazePod. It uses an ESP32-C3 microcontroller to create a wireless, Bluetooth-controlled LED pod that measures reaction time with millisecond accuracy.

Key Features

✅ Wireless BLE 5.0 control
✅ Millisecond-accurate reaction timing
✅ Customizable RGB colors via mobile app
✅ Multiple trigger options: Piezo (slap), Button (press), Accelerometer (shake)
✅ Smooth breathing animations
✅ Modular design - enable/disable sensors as needed
✅ Low power consumption

🔧 Hardware Requirements

Required Components

Component	Quantity	Notes
ESP32-C3 Super Mini	1	Main controller
WS2812B NeoPixel Ring (12 LEDs)	1	5V, 12-LED ring
Piezo Disc	1	Optional - for slap detection
Momentary Push Button	1	Optional - for press detection
ADXL335 Accelerometer	1	Optional - for shake detection
1M Ω Resistor	1	For piezo sensor
3.7V LiPo Battery	1	500-1000mAh recommended
TP4056 Charging Module	1	Battery charging
Slide Switch	1	On/Off power switch

Tools Needed

Soldering iron & solder
USB-C cable (data-capable)
Wire cutters/strippers
Hot glue gun
3D printer (optional, for case)

🔌 Wiring Diagram

ESP32-C3 Super Mini Pinout

Component	ESP32-C3 Pin	Notes
NeoPixel Data	GPIO 3	DIN pin on ring
NeoPixel VCC	5V (VIN)	Use 5V for brightness
NeoPixel GND	GND	Common ground
Piezo (+)	GPIO 4	With 1M Ω resistor to GND
Piezo (-)	GND
Button (Leg 1)	GPIO 5
Button (Leg 2)	GND	No resistor needed (internal pullup)
Accel X	GPIO 6	ADXL335 X-Out
Accel Y	GPIO 7	ADXL335 Y-Out
Accel Z	GPIO 0	ADXL335 Z-Out
Accel VCC	3.3V	⚠️ 3.3V ONLY!
Accel GND	GND

Wiring Schematic

ESP32-C3 Super Mini
┌─────────────────┐
│   GPIO 3  ──────┼──> NeoPixel DIN
│   5V      ──────┼──> NeoPixel VCC
│   GND     ──────┼──> NeoPixel GND, Piezo (-), Button (Leg 2)
│   GPIO 4  ──────┼──> Piezo (+) [with 1MΩ to GND]
│   GPIO 5  ──────┼──> Button (Leg 1)
│   GPIO 6  ────────> ADXL335 X
│   GPIO 7  ──────┼──> ADXL335 Y
│   GPIO 0  ──────┼──> ADXL335 Z
│   3.3V    ──────┼──> ADXL335 VCC
└─────────────────┘

💻 Software Setup

Step 1: Install Arduino IDE

Download from: https://www.arduino.cc/en/software

Step 2: Add ESP32 Board Support

Open Arduino IDE
Go to File > Preferences

Add this URL to "Additional Board Manager URLs":

https://espressif.github.io/arduino-esp32/package_esp32_index.json

Go to Tools > Board > Boards Manager
Search for "esp32"
Install "esp32 by Espressif Systems" (version 2.0.9 or higher)

Step 3: Install Required Libraries

Go to Sketch > Include Library > Manage Libraries
Search and install:
- Adafruit NeoPixel by Adafruit

Step 4: Select Board Settings

Tools > Board: Select "ESP32C3 Dev Module"
Tools > USB CDC On Boot: "Enabled"
Tools > Partition Scheme: "Default 4MB with spiffs"
Tools > Port: Select your ESP32-C3 port

Step 5: Upload Code

Copy the full code into Arduino IDE
Click Verify (✓) to compile
Hold BOOT button on ESP32-C3
Press RESET (or plug in USB while holding BOOT)
Click Upload (→)
Release BOOT button when you see "Connecting..."
Press RESET once after upload completes

⚙️ Configuration

Enable/Disable Sensors

At the top of the code, you'll find:

// --- Feature Toggles (Comment to disable) ---
#define FEATURE_PIEZO
#define FEATURE_BUTTON
#define FEATURE_ACCEL

To enable a feature: Leave the line as is (uncommented)
To disable a feature: Add // at the beginning

Example Configurations

Button Only (Quiet Mode)

//#define FEATURE_PIEZO
#define FEATURE_BUTTON
//#define FEATURE_ACCEL

Slap Only (Classic Mode)

#define FEATURE_PIEZO
//#define FEATURE_BUTTON
//#define FEATURE_ACCEL

Full Features (All Triggers)

#define FEATURE_PIEZO
#define FEATURE_BUTTON
#define FEATURE_ACCEL

Adjust Sensitivity

#ifdef FEATURE_PIEZO
  #define PIEZO_THRESHOLD   1500    // Higher = less sensitive
#endif

#ifdef FEATURE_BUTTON
  #define BUTTON_THRESHOLD  100     // Not used (digital read)
#endif

#ifdef FEATURE_ACCEL
  #define ACCEL_THRESHOLD   150     // Higher = less sensitive
#endif

Change Device Name

#define DEVICE_NAME         "BlazeC3_Pod_01"

Change to any name (max 15 characters).

Adjust LED Brightness

#define BRIGHTNESS          50      // 0-255 (0=off, 255=brightest)
#define BREATHE_MAX         40      // Max brightness for breathing effect

📱 BLE Commands Reference

Connection Details

Parameter	Value
Device Name	`BlazeC3_Pod_01` (or your custom name)
Service UUID	`4fafc201-1fb5-459e-8fcc-c5c9c331914b`
Characteristic UUID	`beb5483e-36e1-4688-b7f5-ea07361b26a8`

Game Control Commands

Command	Description	Response
`START`	Start reaction test	`OK:STARTED`
`RESET`	Stop game, return to connected state	`OK:RESET`

Color Configuration Commands

Format: COLOR_NAME:R,G,B where R,G,B are 0-255

Command	Example	Description
`COLOR_WAIT:0,0,255`	Blue breathing when waiting for connection
`COLOR_CONN:0,255,255`	Cyan when connected, ready
`COLOR_ACTIVE:255,0,0`	Red when game active (wait for trigger)
`COLOR_SUCCESS:0,255,0`	Green when triggered (success)

Responses: OK:COLOR_NAME:R,G,B

Utility Commands

Command	Description	Response Example
`GET_COLORS`	Get all current colors	`COLORS\|WAIT:0,0,255\|CONN:0,255,255\|ACTIVE:255,0,0\|SUCCESS:0,255,0`
`RESET_COLORS`	Reset to default colors	`OK:COLORS_RESET`

Automatic Notifications

Notification	When Sent
`RESULT:245ms`	When trigger detected (reaction time)
`OK:STARTED`	When game starts
`OK:RESET`	When game resets

🎮 Using the Device

Basic Workflow

Power On
- Turn on the slide switch
- LEDs perform rainbow spin (2 seconds)
- LEDs enter breathing blue mode (waiting for connection)
Connect via Bluetooth
- Open nRF Connect or your mobile app
- Scan for BlazeC3_Pod_01
- Tap CONNECT
- LEDs turn solid cyan (connected)
Customize Colors (Optional)
- Send COLOR_ACTIVE:255,0,255 for purple active color
- Send GET_COLORS to verify
Start Reaction Test
- Send START
- LEDs turn red (or your custom active color)
- Wait for the light...
Trigger the Pod
- Slap it (if piezo enabled)
- Press the button (if button enabled)
- Shake it (if accelerometer enabled)
- LEDs turn green (success)
View Result
- Check notification: RESULT:245ms
- Lower = faster reaction time!
Repeat
- Send START again for another round
- Or send RESET to stop

State Indicators

LED Behavior	State	Meaning
🌈 Rainbow spin	Boot	Starting up
💙 Breathing blue	Waiting	No Bluetooth connection
💚 Solid cyan	Connected	Ready to train
🔴 Solid red	Active	Game started - wait for trigger
🟢 Solid green	Success	Triggered! Showing result

📲 Mobile App Testing

Using nRF Connect (Android/iOS)

Download:

Android
iOS

Step-by-Step Testing

Open nRF Connect
Scan for devices
Find BlazeC3_Pod_01
Tap CONNECT
Expand "Unknown Service" (4fafc201...)
Enable Notifications:
- Tap the up arrow (↗️) on the characteristic
- Select "Indicate" or "Notify"
Send Commands:
- Tap the down arrow (↙️) or pencil icon (✏️)
- Type command (e.g., START)
- Select "UTF-8" or "TEXT" format
- Tap SEND
View Results:
- Notifications appear below the characteristic
- Look for RESULT:XXXms

Quick Test Sequence

1. GET_COLORS          → Verify current colors
2. COLOR_ACTIVE:255,0,255  → Set purple active color
3. START               → Begin test
4. [Press button]      → Trigger
5. [See RESULT:XXXms]  → Check time
6. RESET               → Stop

🐛 Troubleshooting

LED Issues

Problem: LEDs don't turn on
Solution:

Check 5V power connection
Verify BRIGHTNESS is not set to 0
Ensure NeoPixel DIN is on GPIO 3

Problem: LEDs flicker or show wrong colors
Solution:

Add 1000μF capacitor across NeoPixel VCC/GND
Add 330Ω resistor on data line (GPIO 3)
Check power supply (use 5V, not 3.3V)

Button Issues

Problem: Button triggers immediately after START
Solution:

Check wiring: Button leg 1 to GPIO 5, leg 2 to GND
Verify FEATURE_BUTTON is enabled
Open Serial Monitor, check button value when NOT pressed (should be HIGH/1)
If reading LOW/0 when not pressed, check for loose wires

Problem: Button doesn't trigger
Solution:

Test with multimeter: Should read 0V when pressed, 3.3V when released
Try increasing BUTTON_THRESHOLD (though digital read shouldn't need this)
Check if FEATURE_BUTTON is commented out

Piezo Issues

Problem: Piezo too sensitive (triggers on its own)
Solution:

Increase PIEZO_THRESHOLD (try 2000-3000)
Ensure 1M Ω resistor is connected between GPIO 4 and GND
Check for loose wires picking up noise

Problem: Piezo not sensitive enough
Solution:

Decrease PIEZO_THRESHOLD (try 800-1200)
Open Serial Monitor, slap piezo, note the value
Set threshold between idle value and slap value

Accelerometer Issues

Problem: Triggers without movement
Solution:

Increase ACCEL_THRESHOLD (try 200-300)
Ensure ADXL335 is powered by 3.3V (not 5V!)
Check wiring is secure

Problem: Doesn't trigger on shake
Solution:

Decrease ACCEL_THRESHOLD (try 80-120)
Verify ADXL335 is working (check X/Y/Z values in Serial Monitor)
Shake harder!

Bluetooth Issues

Problem: Can't find device
Solution:

Ensure device is powered (LEDs breathing blue)
Move closer to phone (within 5 meters)
Restart ESP32-C3 (press RESET)
Check if already connected to another device

Problem: Can't send commands
Solution:

Enable Notifications on the characteristic
Use UTF-8 or TEXT format (not HEX)
Don't include quotes: START not "START"
Check if device is connected (LEDs solid cyan)

Problem: Commands not working
Solution:

Check Serial Monitor for "Received: [COMMAND]"
Verify command spelling (case-sensitive: START not start)
Enable notifications to see responses

Serial Monitor Debugging

Open Serial Monitor:

Baud rate: 115200
Line ending: Newline or Both NL & CR

What to look for:

================================
  BlazePod C3 - Production Ready
================================
Piezo:   OFF
Button:  ON
Accel:   OFF
================================
System Ready - Waiting for connection...
Device Connected
Received: [START]
Game Started
Trigger: Button
Reaction Time: 245ms

🚀 Advanced Features

Building a Mobile App

For a production app, you can use:

Flutter (cross-platform)
React Native (cross-platform)
Swift (iOS only)
Kotlin (Android only)

Key BLE Libraries:

Flutter: flutter_blue_plus
React Native: react-native-ble-plx

Multiple Pods Setup

To build 6 pods for group training:

Change device names:

#define DEVICE_NAME "BlazeC3_Pod_01"  // Pod 1
#define DEVICE_NAME "BlazeC3_Pod_02"  // Pod 2
// etc.

Connect to all pods in your app
Send START to all simultaneously
Collect results from each pod

Power Optimization

Extend battery life:

Reduce BRIGHTNESS to 30-40
Reduce BREATHE_MAX to 20
Add deep sleep after 10 minutes of inactivity
Use smaller battery (300mAh) for lighter weight

3D Printed Case

Design considerations:

Diameter: 100-120mm (to fit 12-LED ring)
Height: 20-30mm (for ESP32-C3 + battery)
Diffuser: 1-2mm thick milky white PLA over LEDs
Mounting: Magnets or velcro on bottom
Button access: Hole or membrane over button
Charging port: USB-C access hole

Recommended settings:

Infill: 20%
Layer height: 0.2mm
Material: PLA or PETG

📊 Performance Specifications

Metric	Value
Reaction Time Accuracy	±1ms
BLE Range	10-40 meters (open space)
Battery Life	4-8 hours (typical use)
Charging Time	2-3 hours
LED Refresh Rate	100 Hz
Touch Response Time	<5ms
BLE Latency	10-20ms (not included in reaction time)

📞 Support & Resources

Code Repository

GitHub: [Your Repo Link]

Community

Arduino Forum: https://forum.arduino.cc/
ESP32 Discord: https://discord.gg/esp32

Tutorials

ESP32-C3 Getting Started: https://docs.espressif.com/
NeoPixel Guide: https://learn.adafruit.com/adafruit-neopixel-uberguide
BLE GATT Tutorial: https://www.bluetooth.com/specifications/gatt/

📄 License

This project is open-source. Feel free to modify, distribute, and use for personal or commercial projects.

✅ Quick Start Checklist

Solder all components
Install Arduino IDE & ESP32 board support
Install Adafruit NeoPixel library
Configure features (comment/uncomment defines)
Upload code to ESP32-C3
Open Serial Monitor, verify boot message
Download nRF Connect app
Connect to BlazeC3_Pod_01
Enable notifications
Send START
Trigger the pod
See RESULT:XXXms
You're ready to train! 🎉

Happy Training! 💪🔥