PulseSensor on CYD (Cheap Yellow Display)

Turn a $15 display into a standalone heartbeat monitor — no coding required.

⚡ Flash Now

Click here to flash your CYD — works in Chrome, Edge, or Opera.

No Arduino IDE needed. Just plug in your CYD and click.

What's a CYD?

The Cheap Yellow Display (ESP32-2432S028R) is a ~$15 development board with a built-in 2.8" color touchscreen. The name was coined by Irish maker Brian Lough, who built a thriving community around it. His ESP32-Cheap-Yellow-Display repo is the go-to resource for CYD projects.

Hardware

You need:

• CYD — ESP32-2432S028R (Amazon or AliExpress, ~$15)
• PulseSensor — pulsesensor.com
• USB cable — micro-USB, data-capable (not charge-only)

Wiring

PulseSensor Wire	CYD Connection
🔴 RED (+V)	3.3V on CN1 connector
⚫ BLACK (GND)	GND on P3 or CN1
🟣 PURPLE (Signal)	GPIO 35 on P3 connector

What You'll See

Once flashed and wired, the display shows:

• BPM — Large heart rate reading
• Waveform — Smooth scrolling pulse wave
• IBI — Inter-beat interval (ms)
• Heart indicator — Flashes red with each beat

When no finger is detected for 3 seconds, the display resets.

Building from Source

If you want to modify the code:

Requirements

• Arduino IDE 2.x
• ESP32 board package (Arduino Core 3.x)
• Libraries:
  • TFT_eSPI by Bodmer
  • PulseSensor Playground

TFT_eSPI Setup

The CYD requires specific TFT_eSPI configuration. Copy User_Setup.h from this repo to your TFT_eSPI library folder, or see Brian Lough's guide.

Compile

1. Open PulseSensor_CYD.ino in Arduino IDE
2. Select board: ESP32 Dev Module
3. Upload speed: 115200 (if 921600 fails)
4. Upload

Export .bin for WebSerial

To update the WebSerial flasher:

Arduino IDE → Sketch → Export Compiled Binary

Copy the .bin file to the firmware/ folder.

File Structure

PulseSensor_CYD/
├── PulseSensor_CYD.ino    # Main Arduino sketch
├── User_Setup.h           # TFT_eSPI config for CYD
├── index.html             # WebSerial flash page
├── manifest.json          # ESP Web Tools config
├── firmware/
│   └── PulseSensor_CYD.bin
├── images/
│   ├── demo.gif
│   └── wiring.png
└── README.md

Customization

Colors and layout are defined at the top of the sketch:

#define COLOR_BG          0x18C3    // Background
#define COLOR_WAVEFORM    0xE1E9    // Waveform line
#define COLOR_BPM         0x4F10    // BPM text
#define COLOR_HEART       0xEA29    // Heart indicator

Troubleshooting

No serial port in flasher?
Try a different USB cable — many are charge-only.

Flat line on waveform?
Check that purple wire connects to GPIO 35.

Erratic readings?
Apply gentle, steady pressure. Insulate the back of your PulseSensor with the velcro dot from your kit.

License

MIT — hack away.

Links

• PulseSensor.com/cyd — Tutorial page
• PulseSensor Playground — Arduino library
• Brian Lough's CYD repo — Community hub

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Made with ♥ by World Famous Electronics