MODULE IHSC

MODULE-IHSC

A thermal imaging module consisting of XIAO RP2040 & MLX90640 for thermal camera and XIAO for the onboard processing which supports usb type c streaming and usb screen sharing extension via an 4 pin I2C extension

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Purpose

The goal of this project was to design a low profile thermal camera module capable of streaming live footage over to the screen via type c and I2C pins

things considerd in mind to make it happen

• PCB design
• CAD
• Components
• Firmware modularization and easy modification

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Features

Core Hardware

• XIAO RP2040
• MLX90640
• 4 Pin I2C horizontal pins
• buzzer for beeping
• tactile switch
• transistor

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Transport & Connectivity

• 4 Pin I2C horizontal pins
• USB-C connection

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Hardware

The PCB is designed using KiCad (open-source) and the case using Fusion 360.

Specifications

• 2-layer PCB
• XIAO RP2040 Proccessing
• MLX90640 heat Camera
• I²C 4 pin connector

All PCB source files are available in /hardware/kicad.

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Firmware

• Thermal Sensing camera

Raw MLX90640 32×24 thermal array with 768 pixels, connected directly via I2C with 110° wide field of view built into the camera and have the abillity to measure −40 °C to +300 °C measurement range Dual I2C bus architecture — sensor on I2C1 (GP6/GP7), display on I2C0 (GP4/GP5) to prevent bus conflicts

• Rainbow Heatmap

Full 7-stop rainbow colour mapping (violet → blue → cyan → green → yellow → orange → red) Bicubic interpolation upscaling from 32×24 to full display resolution which will convert it into Real-time hotspot and coldspot crosshair overlays with temperature labels Live temperature scale bar rendered on-screen

• Dual Output System

USB-CDC mode — binary frame stream over via a Type-C cable to a PC host viewer I2C display mode — frames rendered directly onto an external OLED via the 4-pin PCB connector (SSD1306 128×64 or SH1107 128×128) BOTH mode — simultaneous USB stream and I2C display output Smart startup auto-detection: defaults to BOTH if display and USB host are both detected, I2C is used only if no PC is connected or USB if no display is found

• Output Switching

Short-press mode button cycles USB → I2C → BOTH → USB in real time Long-press mode button saves current mode to flash (persists across reboots) PC-side display_switch.py utility to switch modes remotely over USB without touching the device Soft-reset trigger from PC so new mode activates immediately without unplugging (made for future integration)

• PC Host Viewer (host_display.py)

Live OpenCV window with rainbow heatmap whit support up to 30 fps Bicubic interpolation for smooth upscaled display Adjustable window scale factor and it Cycle's through 5 colour maps: Rainbow, Inferno, Plasma, Bone, Jet and the Temperature range lock/unlock (freeze min–max for consistent colour mapping) and shows Hotspot and coldspot crosshairs with live °C labels and it has a Full-screen toggle Live FPS counter and frame index overlay

• PC Switch Utility (display_switch.py)

Query current output mode from the device which Switchs to the output mode (USB / I2C / BOTH) via command line and Scan the 4-pin I2C connector bus to detect connected display hardware and then the Live frame monitor — prints per-frame FPS, Tmin, Tmax, and checksum status and it also Auto-detects RP2040 serial port (no --port flag needed in most cases)

• Performance

~30 fps live thermal stream at 32 Hz sensor refresh rate in the MLX90640 camera -USB-CDC frame size: 1562 bytes per frame (~47 KB/s, well within USB bandwidth) and uses Binary framing protocol with magic header and checksum validation for data integrity and Frame index tracking for dropped frame detection

• Hardware Controls

Power button (GP28): short press pauses/resumes streaming; long press enters light-sleep Mode button (GP29): short press cycles output mode; long press saves mode to flash Buzzer (GP27): distinct beep patterns for each event — power-on, mode switch (unique per mode), mode saved, sleep, and error

• Buzzer Feedback

Single long beep on power-on 1 beep = USB mode selected 2 beeps = I2C display mode selected 3 beeps = BOTH mode / mode saved to flash Double beep = entering sleep 5 rapid beeps = sensor not found (wiring error)

• Persistent Configuration

Output mode saved to output_mode.json on the RP2040's onboard flash Automatically restored on every reboot with no user intervention

Firmware files are located in /firmware.

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Images

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BOM

The complete bill of materials (BOM), including purchase links, is available in
/hardware/bom.csv.

Manufacturing & sourcing:

• PCB fabrication: JLCPCB

• Components (India): Robu.in

• Enclosure: Online 3D printing services (if needed)

  

Bill of Materials

please note that most of the parts are from indian suppliers !

*note there's also a transistor in the project (2N2219) but it's not available anywhere online for me that's why it's not included in the BOM with price and link

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License

This project is open-source hardware and software and is released under the MIT License.