PulseSensor on the Waveshare ESP32-S3-RLCD-4.2 — LiveCyberDeck

A standalone PulseSensor heart-rate dashboard for the Waveshare ESP32-S3-RLCD-4.2, the maker board with a 4.2″ ST7305 400 × 300 monochrome reflective LCD. Flash it from your browser, wire three pins, and watch your live pulse on a daylight-readable screen — no app, no WiFi, no IDE.

This is the reflective-LCD sibling of the color-touchscreen PulseSensor CYD. The firmware is called LiveCyberDeck.

Educational biofeedback demo. Not a medical device and not intended for medical use.

Flash it from your browser

The easiest path — no toolchain required:

1. Tutorial + one-click installer: pulsesensor.com/pages/waveshare-rlcd
2. Web installer (this repo, via GitHub Pages): worldfamouselectronics.github.io/esp32-s3-RLCD-4.2

Use Chrome, Edge, or Brave on a desktop or laptop (WebSerial is required; mobile browsers don't support it yet).

Putting the board in flashing mode: the ESP32-S3 native USB does not auto-reset into the bootloader. Before clicking Install, hold BOOT, tap RST while holding BOOT, then release BOOT. Then pick the board's USB serial port.

Wiring

The board exposes a rear 2 × 8 female header. Match the PulseSensor's three wires to the printed labels:

PulseSensor wire	Waveshare rear header
Red — +V	3V3
Black — GND	GND
Purple — Signal	GP1 / GPIO1 / ADC1_CH0

Use 3V3, not VBUS. The firmware reads the sensor on GPIO1, so the purple signal wire goes to the lower-row GP1 socket (4th lower pin from the left in the line art below). Powering from VBUS can clip or flatten the waveform.

• Rear-header line art (GP1)
• Three-wire schematic
• Block diagram

What you'll see

LiveCyberDeck opens with a boot splash, then a live dashboard:

• Live pulse window — a solid scrolling waveform with open/filled beat circles and a dashed TRIGGER line at the detection threshold.
• Signal status & strength — SIGNAL SEARCH → QUALIFIED BEAT, paired with a strength meter that fills as the signal locks.
• Big BPM & IBI panels — each with a large readout plus an edge-to-edge sparkline of recent qualified beats and low / normal / high reference lines.
• Header telemetry — a heart that pulses on each qualified beat, battery % + voltage, onboard SHTC3 temperature & humidity, firmware version, and a live UP h:mm:ss uptime.
• Light / dark toggle — tap KEY (GPIO18).

Hardware & pinout

Waveshare ESP32-S3-RLCD-4.2 — ESP32-S3, 16 MB flash, 8 MB PSRAM, ST7305 400 × 300 reflective LCD.

Function	Pin
PulseSensor signal	GPIO1 (ADC1_CH0, rear-header GP1)
Display SCK / MOSI	GPIO11 / GPIO12
Display DC / CS / RST	GPIO5 / GPIO40 / GPIO41
KEY button (light/dark)	GPIO18
BOOT button	GPIO0
I²C SDA / SCL (SHTC3 @ 0x70)	GPIO13 / GPIO14
Battery sense	ADC1_CH3 (GPIO4)

PulseSensor Playground expects 10-bit samples, so the firmware calls analogReadResolution(10) at startup; the beat threshold (TRIGGER line) starts at setThreshold(550). Battery and SHTC3 readouts are optional — the dashboard runs without them.

Build from source

This is a PlatformIO Arduino/C++ project (env waveshare_rlcd42).

# build
platformio run -e waveshare_rlcd42

# build + flash (put the board in flashing mode first: hold BOOT, tap RST, release BOOT)
platformio run -e waveshare_rlcd42 -t upload

# serial monitor
platformio device monitor -b 115200

Firmware name/version/date come from the APP_NAME / APP_VERSION / APP_DATE build flags in platformio.ini.

The pre-built binaries in firmware/ and manifest.json are what the browser installer flashes (ESP Web Tools).

Built on PulseSensor Playground

Every reading comes from the PulseSensor Playground library — getLatestSample(), sawStartOfBeat(), isInsideBeat(), getBeatsPerMinute(), getInterBeatIntervalMs(), getPulseAmplitude() — with the "snappy-lock" beat-detection behavior carried over from the CYD build.

License

MIT — see LICENSE. Made by World Famous Electronics. Heartbeats in your project, lickety-split. ♥