Carmelit, which is an underground funicular railway in Haifa, raised a need for a device that can monitor Indoor air quality (by CO_2 level) and the number of people at stations. The project goal is an implementation of an IOT device which is small, portable, inexpensive and meets the Carmelit requirements.
This project comprises design and building of an IOT device that is a small, low power, cheap and self-sustained system that measures level, temperature, humidity, number of people who leaves the station, and it allows data transmission to gateway.
The system consists of : microcontroller ,ESP32 ,which controls the system ,collects the sampled data from the sensors ,analyzes and processes it.
It also includes two sensors ,SCD30 – the air quality sensor ,VL53LOX – the distance sensor – used for detecting passing passengers, transmitter (LoRa RFM96) and a power management block which activates the system and provides the needed power to each part on the board .Moreover ,The power management block also charges a rechargeable battery while the system supplied by external Power Source. The system is self-sustained because of the design of the power management block, without external power the charged battery can activate the system independently.
All the components in the design were chosen based on size , price and power consumption resulting in low power, cheap and small PCB.
The system components require two different voltage values :The ESP32 and LoRa require 3.3v ,whereas the SCD30 and VL53LOX require 5v. As a result ,the design of the power management block was made accordingly ,meaning, in it’s output there are two voltage values.
