HealthyPi 5 NEXT — Arduino Firmware

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v2.0.0 is a complete rewrite — the production NEXT dual-core architecture, packaged as an Arduino library. The previous 2023 sketches are preserved on the v1-legacy tag. The ESP32-C3 (BLE / Wi-Fi) firmware has moved to healthybridge-esp32. See CHANGELOG.md.

Arduino-framework firmware for the ProtoCentral HealthyPi 5 biosignal monitoring board (RP2040 main MCU). It is the maker- and educator-friendly member of the HealthyPi 5 NEXT firmware family: from single-sensor sketches you can read top to bottom, up to a full dual-core firmware that is byte-compatible with OpenView 2 and the production NEXT firmware.

HealthyPi 5 is an open-source development board for exploring biosignals — electrocardiogram (ECG), respiration, photoplethysmography (PPG), oxygen saturation (SpO₂), and body temperature.

This repository is the Arduino firmware for the RP2040 Main MCU. Wireless (BLE / Wi-Fi) is not handled here — it is done by the companion ESP32-C3 "HealthyBridge" co-processor firmware in Protocentral/healthybridge-esp32, which speaks the same UART HealthyBridge wire protocol. See Wireless.

Important

You must also update the ESP32-C3 firmware. The v2 NEXT firmware in this repository talks to the co-processor over the HealthyBridge Lite binary protocol, which the pre-v2 ESP32-C3 firmware does not speak. Flash the matching release of healthybridge-esp32 onto the ESP32-C3 as well — otherwise the RP2040 side runs fine, but BLE and Wi-Fi will not work. Everything over USB (OpenView 2, the command plane) and SD recording is unaffected.

Why "NEXT"?

The earlier HealthyPi 5 Arduino sketches were single-core and streamed on a best-effort basis — under load they could drop samples, and several public examples were mis-pinned for current board revisions. NEXT is the ground-up rebuild of the HealthyPi 5 firmware around a dual-core, lossless-by-design data path: one RP2040 core does nothing but acquire sensor samples, while the other runs every consumer (DSP, USB/OpenView, SD, wireless bridge) as a scheduled task. The two cores communicate through a single lock-free ring, which makes guaranteed-lossless 128 SPS sampling a property the architecture enforces rather than one you tune for.

This repository brings that same NEXT architecture to the Arduino framework (the arduino-pico core), so makers and educators get the robust production design in an Arduino IDE workflow — while staying byte-compatible with the NEXT firmware and OpenView 2 so it interoperates with the rest of the ecosystem.

Hardware features

• RP2040 dual-core ARM Cortex-M0+ Main MCU, 16 MB onboard flash
• ESP32-C3 RISC-V co-processor with BLE and Wi-Fi (separate firmware)
• MAX30001 analog front end — ECG and respiration
• AFE4400 analog front end — PPG (SpO₂)
• MAX30205 I²C body-temperature sensor
• MicroSD card slot for onboard recording
• On-board Li-Ion battery management with USB charging
• 40-pin Raspberry Pi HAT connector (also drives the Display Add-On Module)

Revisions 5.2 through 5.7 are electrically identical, so one pin map serves all of them — see docs/PIN_MAP.md.

The firmware family

Repo	MCU	Framework	Role
healthypi5_next_rp2040	RP2040	Pico SDK + FreeRTOS	production main MCU (lossless, dual-core)
healthybridge-esp32	ESP32-C3	ESP-IDF + NimBLE	production wireless co-processor
healthypi5_next_arduino (this)	RP2040 (+ESP32-C3)	Arduino	teaching / maker reference, OpenView-compatible

What's in this repo

Folder	What it is
libraries/HealthyPi5/	The runtime library: the canonical board.h pin map and the dual-core NEXT spine (acquisition, broker, OpenView, HealthyBridge, SD, watchdog).
examples/Tutorials/	11 standalone sketches (01–11), one signal/idea at a time, for the Serial Plotter/Monitor, OpenView 2, wireless, and SD logging. Start here to learn the board.
examples/Applications/	The full dual-core NEXT firmware (headless).
scripts/	install-core.sh, build.sh, upload.sh — one-command setup, compile, and flash (see Command-line workflow).
extras/docs/	Pin map and the two-chip wireless model. See Documentation.

Getting started (Arduino IDE)

1. Install the board core. In Boards Manager, install arduino-pico (Earle Philhower). Select board "Raspberry Pi Pico".
2. Install the sensor libraries (Library Manager):
   • ProtoCentral MAX30001 — v2.0.0 or newer (ECG / BioZ / heart rate)
   • ProtoCentral AFE4490 PPG and SpO2 boards library — provides the AFE4400 driver and the SpO₂ algorithm (the board's PPG AFE is an AFE4400, not a MAX3010x)
3. Install the HealthyPi5 library. Copy libraries/HealthyPi5/ into your Arduino libraries folder (e.g. ~/Documents/Arduino/libraries/). It provides the canonical board.h every sketch uses.
4. Open a sketch from examples/ — e.g. examples/Tutorials/01_ECG_Plotter — and click Upload.
   • For the Applications (examples/Applications/…), also set Tools → os: "FreeRTOS SMP" before uploading.
5. View the output: open Tools → Serial Plotter (or Serial Monitor) at 115200 baud for the teaching sketches; use OpenView 2 for the multi-channel binary stream.

Prefer the command line? See Command-line workflow at the end — it also flashes over the Raspberry Pi Debug Probe.

The HealthyPi5 library

libraries/HealthyPi5/ plays two roles:

• board.h — the single source of truth for pins (rev 5.2–5.7). Every sketch includes it via the HPI_PIN_* macros, so no GPIO is ever hardcoded. The 9 basic teaching sketches use only this.
• The dual-core runtime — the whole NEXT spine (core1 lossless acquisition into a lock-free ring; core0 broker + per-sink queues + OpenView + HealthyBridge
  • SD + telemetry + hardware watchdog). The Applications are thin sketches over it. Requires the arduino-pico FreeRTOS-SMP variant (#include <FreeRTOS.h>).

On-panel display (LCD) is not supported in this release. The board's HAT connector can drive the Display Add-On Module, but the LVGL vitals-screen driver is still in bring-up and has been held back. It will return in a later version.

Tutorials (examples/Tutorials/)

Single-purpose, read-top-to-bottom sketches. 01–07 bring up one sensor each; 08–11 are the more advanced ones (OpenView, your-own-DSP, wireless, SD).

#	Sketch	Sensor	How to view it
01	01_ECG_Plotter	MAX30001 (ECG)	Serial Plotter @ 115200
02	02_Respiration_Plotter	MAX30001 (BioZ)	Serial Plotter
03	03_PPG_Plotter	AFE4400	Serial Plotter (IR + RED)
04	04_SpO2	AFE4400	Serial Monitor (SpO₂ %, no-finger safe)
05	05_HeartRate	MAX30001 (RtoR)	Serial Monitor (bpm + R-R)
06	06_Temperature	MAX30205 (I²C)	Serial Monitor (°C, absent-safe)
07	07_Vitals_Serial	all three	Serial Monitor (combined line)
08	08_OpenView_Stream	all sensors	OpenView 2 (29-byte binary frame)
09	09_RawProcessing	all sensors	your own DSP in loop() over the dual-core spine
10	10_Wireless_Bridge	all sensors	ESP32-C3 → BLE / Wi-Fi (HealthyBridge)
11	11_SD_Datalog	all sensors	record raw waveforms to a microSD card (/REC*.BIN)

See examples/Tutorials/README.md for setup, pins, and tips.

Two visualisation paths

• Arduino Serial Plotter / Monitor — the right tool for single- or few-channel numeric output (sketches 01–07), at 115200 baud.
• OpenView 2 — for the full multi-channel binary stream (08 and the Applications). The Serial Plotter can't parse that packet; that's the one thing it doesn't do.

Application firmware (examples/Applications/)

The complete headless firmware, a thin sketch over the HealthyPi5 library. Needs os: FreeRTOS SMP.

Sketch	What it does
HealthyPi5_NEXT	The full headless firmware: lossless dual-core acquisition, OpenView 2 over USB-CDC, host command plane, config persistence, SD recording, I²C temp/battery, and the HealthyBridge link to the ESP32-C3. 1 Hz HPI_INSTR telemetry + hardware watchdog.

Wireless (BLE / Wi-Fi)

Important

The ESP32-C3 firmware must be updated for this firmware to fully work. The RP2040 ↔ ESP32-C3 link uses the HealthyBridge Lite binary framing (0xAA55 | type | flags | len | seq | payload | crc16), which is new in v2 and is not understood by the ESP32-C3 firmware that shipped with the v1 sketches. Until you flash the matching healthybridge-esp32 release, the RP2040 will stream frames the co-processor silently ignores: no BLE, no Wi-Fi. (It never stalls acquisition — the bridge is a drop-newest sink, so USB/OpenView and SD keep working regardless.)

Read the two counters in the 1 Hz HPI_INSTR telemetry line on UART0 to tell the two failure modes apart: a climbing hbdrop= means the ESP32-C3 is absent or not draining the UART at all, whereas hbtx= climbing with hbdrop=0 means the link is up and the co-processor is reading frames — if BLE is still dead in that state, it is running mismatched firmware.

The RP2040 has no radio — it's a plain RP2040, not a Pico W. All wireless is done by the on-board ESP32-C3, which runs its own firmware, healthybridge-esp32, and owns both radios. The RP2040 streams to it over the HealthyBridge UART link; BLE and Wi-Fi share the same RP2040-side code — the radio is chosen on the ESP32. Learn the wire format in 10_Wireless_Bridge; see docs/WIRELESS.md for the two-chip model and bring-up.

The ESP32-C3 firmware previously lived in an esp32/ folder in this repository; it moved to healthybridge-esp32 in v2.0.0, and the v1 sketch is preserved on the v1-legacy tag.

Command-line workflow (scripts/)

For CI, batch builds, or flashing over the Raspberry Pi Debug Probe, the repo ships three scripts (need arduino-cli):

Script	Purpose
./scripts/install-core.sh	Register + install the arduino-pico core and the ProtoCentral sensor libraries. Idempotent.
./scripts/build.sh <target>	Compile one target (or all / tutorials) against the in-repo library.
./scripts/upload.sh <target>	Build + flash. Default programmer is the Raspberry Pi Debug Probe (SWD); --serial falls back to USB/UF2, --monitor opens the UART console.

./scripts/install-core.sh                 # one-time setup
./scripts/upload.sh ecg --monitor         # teaching: ECG on the Serial Plotter/Monitor
./scripts/upload.sh next                  # HealthyPi5_NEXT (OpenView 2 + wireless + SD)

Targets: next · openview · raw · datalog · ecg resp ppg spo2 hr temp vitals wireless · tutorials (all standalone tutorial sketches) · all.

Documentation

• extras/docs/PIN_MAP.md — authoritative pin map + what the old sketch got wrong.
• extras/docs/WIRELESS.md — the RP2040 ↔ ESP32-C3 two-chip wireless model.

License

MIT (first-party firmware). Third-party libraries retain their own licenses.