See my write-up on IoT with Mongoose OS. Here you can find a brief write-up about my projects based on Mongoose OS and my general experience with this IoT platform.
This is a Mongoose OS project containing a configuration template and code written in the so-called minimal JavaScript or mJS.
This project makes use of the ESP32 GPIO interrupt mode to act as a basic counter. When using the LDR Sensor Module, the photo-diode can be placed on the LED indicator of a prepaid electricity meter to tally metered kWh units fairly precisely. The model is useful because it allows the photo-diode sensitivity to be appropriate for the LED on the device. In some early testing, I got an appreciation for how quickly the interrupt handling is when I was incorrectly counting the 50Hz ripple in the LED brightness and it was necessary to filter it out. As an added level of resilience, I would also "debounce" the input according to the maximum theoretical current draw of the household through the meter.
At startup, the counter can start in one of two modes. The default mode is GPIO-interrupt where the interrupts are responsible for incrementing the counter and a separate timer is responsible for doing the accounting on the register value. The other mode uses a polling approach and the analog-to-digital converter (ADC). I left both implementations in the code because it is useful, tested boilerplate for other projects.
Depending on whether the counter is set to incrementing or decrementing, the counted values update a register_reading as part of a few other useful fields in an MQTT publish message. The meter also subscribes to a topic meter/electricity/control/# to enable remote resetting of the register. A tempting addition is to automatically read the real register value using some kind of non-invasive image recognition but that is outside the scope of this project.
Technologies that help make this project useful:
Here is some detail about the intended use of this project.
Your development environment needs to have the mos tool available to build firmware binaries and for first-time configuration of the device. Mongoose OS has a good getting started guide with installation instructions.
The Mongoose OS documentation provides a detailed but concise instruction on how to use the mos tool to build the binaries that can then either be flashed directly to a USB-connected IoT device or that can be uploaded to the mDash site and delivered as an OTA update.
Distributed under the MIT License. See LICENSE for more information.
