2 layers65 × 50 mm HIVIS2, the printed circuit board in 3D

HIVIS2

Self-hosted indoor air quality and acoustic monitoring system built on ESP32. Designed for schools, offices, and research environments where privacy and data ownership matter.

Full screen GitHub .kicad_pcb

Size: 65 × 50 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 15
Nets: 34
Pads: 75
Tracks, vias: 88, 5
Pours: 1
Routed: Yes
KiCad: KiCad 9.0 (file 20241229)
Created: 27 Apr 2026
Updated: 4 May 2026

Overview

HIVIS2 is an open-source printed circuit board by ranieriv, from the ranieriv/HIVIS2 repository on GitHub. It is a 2-layer board of 65 × 50 mm with 15 parts on 34 nets, routed with 88 tracks and 5 vias.

It is built around the INMP441. Its parts include 5 resistors, 5 connectors, 2 capacitors, 1 IC and 1 switch.

Main components

INMP441
SMD-960Hz~15kHz SMD-9 MEMS Microphones ROHSTDK InvenSenseMEMS Microphones

README

README.md

HIVIS Monitor 2.0

Self-hosted indoor air quality and acoustic monitoring system built on ESP32. Designed for schools, offices, and research environments where privacy and data ownership matter.

Live dashboard: https://hvht.net

What it measures

Metric	Sensor	Notes
IAQ (Air Quality Index)	BME688 + BSEC2	0–500 scale, accuracy 0–3
CO₂ equivalent	BME688 + BSEC2	ppm
VOC (breath VOC)	BME688 + BSEC2	ppm
Temperature	BME688	°C
Humidity	BME688	% RH
Noise level	INMP441	dB SPL
Battery voltage	ADC (GPIO 36)	% + volts

Architecture

text

┌─────────────────────────────────────────────────────┐
│  ESP32 Device (battery-powered)                     │
│  BME688 · INMP441 · OLED · Button · Buzzer          │
└──────────────────┬──────────────────────────────────┘
                   │ MQTT TLS :8883 · HTTP :8090 (OTA)
                   ▼
┌─────────────────────────────────────────────────────┐
│  Server (Docker)                                    │
│  Mosquitto → Node-RED → InfluxDB → Grafana          │
│  Nginx (https://hvht.net) · OTA server (:8090)      │
└─────────────────────────────────────────────────────┘

Hardware

Component	Part
MCU	ESP32 DOIT DevKit V1
Air quality	Bosch BME688 breakout
Microphone	INMP441 I2S breakout
Display	0.96" OLED SSD1306 (I2C)
Button	Tactile switch (GPIO 4)
Buzzer	Passive piezo (GPIO 25)
Power	1S LiPo + USB-C charging module

KiCad schematic, PCB layout, Gerber files, and BOM are in hardware/.

GPIO Map

GPIO	Function
21	I2C SDA (BME688 + OLED)
22	I2C SCL (BME688 + OLED)
12	I2S WS — microphone
13	I2S LR — microphone channel select
14	I2S SCK — microphone
26	I2S SD — microphone data
4	Button (INPUT_PULLUP, active LOW)
25	Buzzer (LEDC PWM)
36	Battery ADC (voltage divider ×2.2)

Firmware

Built with PlatformIO (Arduino framework).

Dependencies (auto-installed via platformio.ini):

boschsensortec/bsec2 — IAQ/CO₂/VOC
olikraus/U8g2 — OLED display
bblanchon/ArduinoJson
knolleary/PubSubClient — MQTT
tzapu/WiFiManager — captive portal provisioning

Build and flash:

bash

# Install PlatformIO CLI or use the VS Code extension
pio run --target upload

# Upload LittleFS (config.json, bsec_state.bin)
pio run --target uploadfs

First boot: the device launches a captive portal (HIVIS-Setup-XXXX). Connect and enter your WiFi credentials and MQTT server address.

Device configuration lives in data/config.json. All pin assignments and thresholds are overridable there without reflashing.

Server

The full server stack runs on Docker. A single Linux machine is enough (tested on a Lenovo ThinkPad X200 with Ubuntu).

Services:

Container	Purpose	Port
`hivis-mosquitto`	MQTT broker (TLS)	8883
`hivis-nodered`	Data routing + device provisioning	1880
`hivis-influxdb`	Time-series storage	8086
`hivis-grafana`	Dashboards	3000
`hivis-ota`	Firmware update server	8090
`hivis-nginx`	Public HTTPS dashboard	80, 443
`hivis-certbot`	Let's Encrypt auto-renewal	—

Deploy:

bash

cd server
cp mosquitto/config/passwd.example mosquitto/config/passwd  # create credentials
docker compose up -d

See docs/system-overview.md for the full setup and docs/operations-manual.md for day-to-day operations.

Button functions

Press	Duration	Action
Short	< 400 ms	Next display page
Double	2× within 400 ms	Stop alert buzzer
Long	2–5 s	Launch reconfigure portal
Factory reset	> 5 s	Wipe NVS credentials and reboot

Documentation

File	Contents
`docs/system-overview.md`	Architecture, pin map, boot sequence, MQTT topics, server stack
`docs/operations-manual.md`	Quick checks, troubleshooting, deploying firmware, adding devices
`spec/01_device_firmware.md`	Firmware module details
`spec/02_provisioning.md`	First-boot captive portal and MQTT registration flow
`spec/03_ota.md`	OTA update system
`spec/04_mqtt_data.md`	MQTT topics and JSON payload schema
`spec/05_server_infrastructure.md`	Docker stack and Mosquitto ACL
`spec/06_grafana_dashboards.md`	Dashboard definitions

Project structure

text

hivis2/
├── src/            # ESP32 firmware (C++/Arduino)
├── data/           # LittleFS filesystem (config.json)
├── hardware/       # KiCad schematic, PCB, Gerbers, BOM
├── server/         # Docker stack, Mosquitto, Node-RED, Grafana, Nginx
├── docs/           # Operations manual + system overview
├── spec/           # Detailed technical specifications
├── partitions.csv  # ESP32 flash partition table
└── platformio.ini  # Build configuration

Project files

Show this board on your page

https://pcbkit.io/boards/ranieriv/HIVIS2

The board's own page, for a message or a post.

Source

Repository: ranieriv/HIVIS2
Board file: hardware/hivis2.kicad_pcb
Commit: 536537c
Licence: Not stated

Parts

Qty	Value	Footprint	References
2	100K	Resistor_SMD:R_0402_1005Metric	R3, R4
2	100nF	Capacitor_SMD:C_0402_1005Metric	C1, C2
2	4.7K	Resistor_SMD:R_0402_1005Metric	R1, R2
1	220	Resistor_SMD:R_0402_1005Metric	R5
1	BATT JST	Connector_JST:JST_PH_B2B-PH-K_1x02_P2.00mm_Vertical	J5
1	BME_688_Module	Library:BME688_Breakout_7pin	J1
1	Buzzer	Buzzer_Beeper:Buzzer_TDK_PS1240P02BT_D12.2mm_H6.5mm	BZ1
1	INMP_441	Library:INMP441_Breakout_8mm	J2
1	J5019_Module	Library:J5019_Module	J4
1	OLED Display	Library:OLED_SSD1306_27x27	J3
1	SW_Push	Button_Switch_THT:SW_PUSH_6mm	SW1
1	~	ESP32_Footprints:ESP32_30pin	U1

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Questions

How big is the HIVIS2 PCB?

It measures 65 × 50 mm and has 2 copper layers, 1.6 mm thick.

What parts does the HIVIS2 use?

15 parts, built around the INMP441. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the HIVIS2 KiCad files?

From the ranieriv/HIVIS2 repository on GitHub, at the commit this page was made from: the board is hardware/hivis2.kicad_pcb and its schematic hardware/hivis2.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the HIVIS2 design in my own project?

Its repository states no licence, so its author keeps all rights: ask ranieriv before reusing the design.