Thermal Camera Streamer

In brief, ESP8266 streams the thermal data captured with GY-MCU90640 module to web clients. The project is inspired by The Easiest Thermal Camera Build You’ll Ever See.

Features

• The 32x24 thermal frames, taken with the MLX90640 sensor, are streamed by ESP8266 to HTML5 capable web clients, where the frames are interpolated and shown on web UI;
• The frame sequence, accumulated in web browser memory, can be saved as a file for later playing back and analyzing;
• Web UI allows setting of up to 10 points for monitoring the temperature of any of the existing 768 points of the thermal picture, those points are persisted in file along with the thermal frames;
• Wi-Fi connection (e.g. AP configuring, or connecting to the existing Wi-Fi network) can be configured through the Web interface;
• Everything needed for streaming thermal data and showing it on browser is hosted on ESP8266 HTTP server locally, so no Internet required;
• There is a built-in IDE for editing the software through Web interface (useful if there is a plenty of space left on ESP flash file system);
• Up to 3 simultanious web sessions are allowed to receive a stream of thermal frames. If fourth client connects, the server removes the oldest web client recepient. The maximum amount of simultanious client sessions may be later increased if the code is executed on more powerful NodeMCU hardware, e.g. ESP32 (not checked yet);
• Responsive Web UI (usable from smartphones);
• NodeMCU version agnostic (polyfills allow to work on on NodeMCU 1.5.4.1 - 3.0.0).

Web UI overview:

Thermal data player UI demo

Navigate the following link to play back pre-recorded thermal data.

UI overview:

Setup Wi-Fi access point:

Setup admin authentication:

BOM

• GY-MCU90640 module. The module consists of MLX90640 thermal sensor array, and STM32 microcontroller that allows communication through serial port. Please refer to GY-MCU90640 User Manual for details.
• ESP8266 module (any board shall fit ok here, but if you are going to hack the software using built-in IDE, the board with more than 512Kb of FLASH is preferable).

Schema

The schematic diagram can't be simpler:

• connect TX of the GY-MCU90640 to RX of the ESP8266;
• connect RX of the GY-MCU90640 to TX of the ESP8266;
• supply the power for both modules (note, that GY-MCU90640 accepts any voltage between 3V and 5V, while ESP module usually requires 3.3V). If you use a simpler ESP module (like ESP-01), rather than ESP Dev Board (NodeMCU module), you may have to wire more ESP pins (usually CH_PD and RST must be connected to +3.3v). Here is a prototype I used for debugging:

Setup

1. Flash the ESP8266 module with the NodeMCU firmware as described in Flashing the firmware with any tool you like (e.g. esptool.py, NodeMCU Flasher etc.). The custom NodeMCU firmware can be built online with the service: NodeMCU custom builds. If your ESP8266 EEPROM is only 512Kb, you have to take extra steps to be sure that firmware is as small as possible, and there is enough space for project files in EEPROM file system. So, build your custom firmware based on 1.5.4.1-final NodeMCU with the only 8 modules selected: cjson, encoder, file, net, node, tmr, uart, wifi, no TLS, no debug, and take the integer version of it (its size is 395300 bytes in my case). In the case if your ESP module goes with larger EEPROM installed, you can build even the most recent NodeMCU version (select the release option on online build tool) with more modules selected, just make sure that at least 70Kb of file system space is available when you run NodeMCU. Make sure the following 8 modules are selected when you are building the firmware:

• encoder;
• file;
• net;
• node;
• SJSON (for new NodeMCU; if you build older NodeMCU (1.5.4.1) select cJSON instead);
• timer;
• UART;
• WiFi.

2. Upload the project files (all the files from src/ directory) to the ESP module (read the Uploading code how to do it). If you prefer, you can use the tool for uploading NodeMCU files from https://github.com/dev-lab/esp-nodemcu-lua-uploader. Upload the software with either install.sh, or install.bat depending on your OS.
3. Restart the ESP8266 module (turn it off and turn back on). After restarting you will see a new Wi-Fi access point with the name: esp-devlab-setup. You will be able to connect to the module with the default password: We1c0me!. The default Wi-Fi AP name and password are specified in file: connect.lua.
4. On successful connection to the esp-devlab-setup Access Point you will be able to reach the Web UI through the browser by typing anything looking like domain name as an URL, e.g.: any.site.my. You can do that because the software starts a DNS liar server (it responds with the ESP8266 IP to any DNS request) in AP mode.
5. The thermal sensor module has to be initialized. For doing that, you have to navigate to Configure tab of Web UI, and press Setup button in Setup the thermal sensor section. After a couple of seconds, on successful initialization, you will see the message: Turn-off and then turn-on the power to complete setup.. That means that the thermal module was initialized and setting are stored in CY-MCU90640 EEPROM. After that, turn-off power supply for both modules, and then turn-on for normal use. That procedure shall be done only once, here is short video: Setup the thermal sensor.
6. Web UI shall be quite self-explaining to use. You only have to remember that the best way to brick the software is to use Web IDE without checking twice what you are uploading to the file system. The changes are taken into account immediately. A bricked NodeMCU can be cured only with connecting of ESP module to computer through UART, formatting of NodeMCU file system, and rewriting the Lua software. In some cases you even have to re-flash the NodeMCU (e.g. if you did the mistake and removed the delay in init.lua.

License

Copyright (c) 2020-2021 Taras Greben

Licensed under the Apache License.