Week One

 Week One


Project Overview:

This projects aims to create an adequate gas safety system for vehicles. It is an embedded system that checks for high levels of Carbon Monoxide (CO) gas and opens the vehicle's windows slightly (approximately 2cm) until the air is safe to breathe again. Moreover, it switches off the AC to allow quicker gas exchange. It also sounds an alarm and displays a warning message to alert the passenger/s of the high levels of CO. However, since this is a prototype and simulating the system with actual CO would be extremely dangerous, the system checks for high levels of CO2 and performs the same operations. Furthermore, the system also senses and displays the overall quality on a screen.



This Week's Overview:

We mainly focused on testing all of our components to make sure they were all working up to an acceptable standard.



Main Tasks:

1) The Raspberry Pi Pico W did not have any headers/pins soldered to it; therefore, we soldered wires onto the 3.3V and GND pins as a temporary solution. However, this fix would not have worked as well with the rest of the GPIO pins required since we were merely testing the components and were not seeking permanent connections to the Raspberry Pi Pico W yet.


2) Regardless, all the different components were tested separately to make sure they read the values correctly:


- Temperature and Humidity sensor (DHT11)

        

        Figure 1: DHT11 Temperature and Humidity Sensor [1].

This sensor is a digital device that requires only one bus; therefore, the code to test it was very straight forward since it uses the "dht" library on Micro-Python. Its purpose in our system is to measure the temperature and humidity levels inside the vehicle to display those measurements on an E-Paper Display.



- Air Quality sensor (MQ-135)

        

        Figure 2: MQ-135 Air Quality Sensor [2]


This Air Quality Gas sensor by MikroeElektronica was tested to measure CO2 levels and other organic compounds in the air. We were mainly using this reading to check whether the CO2 levels are unsafe for breathing. A major issue we ran into was that this sensor did not have an exact calibration so the voltage (V) to parts per million (ppm) relationship was not accurate.



- CO Gas Quality sensor (MQ-9)

Figure 3: MQ-9 CO Gas Quality Sensor [3]

This MQ-9 gas sensor measures CO gas in its environment. The same issue arose here like it did for the MQ-135 sensor; the calibration for this sensor was not accurate either.



- Stepper Driver and Motor

        

Figure 4: Stepper Driver and Motor [4]


The stepper driver is used to generate an adequate signal from the input voltage (5V) to move the stepper motor in "steps" which follows a certain sequence. Stepper motor's angle rotation and speed can be accurately controlled. This stepper motor is used to help simulate the window's movement. However, because the driver was not soldered onto the Raspberry Pi Pico W, the motor was not running properly; it was essentially just vibrating. This vibration could also be resolved by reducing the delay between each step.



- E-Paper display

Figure 5: E-Paper Display [5]


This E-Paper Display made by Waveshare is able to keep text and images displayed on it even without any power running through it. This essentially means that it requires less power than other electronic screens. It can also be viewed clearly even when exposed to direct sunlight since it is meant to replicate actual ink on paper, hence the name. We use this E-Paper in our gas safety system to display the statistics gathered from all the different sensors. Furthermore, when the gas levels are unsafe, it will display a warning message.



Issues Faced:

- The E-Paper Display and stepping motor were not functioning properly which could be fixed if the pins were directly soldered onto the Raspberry Pi Pico W.


- The MQ-9 and MQ-135 gas sensors were not calibrated accurately.



Next Week:

- Creating sensible block and circuit diagrams.


- Testing out the rest of the components.


- Constructing the full circuit.


- Combining the different bits of code to check that they work in unison.


References:

[1]     RS Components,"Seeed Studio Temperature and Humidity Sensor for DHT11 Grove System", RS Components.[Online].Available: https://uk.rs-online.com/web/p/sensor-development-tools/1743237?gb=s. [Accessed: Jan. 30, 2025].

 

[2] RS Components,"MikroElektronika Air Quality click Gas Sensor mikroBus Click Board for MQ-135", RS Components.[Online].Available: https://uk.rs-online.com/web/p/sensor-development-tools/8829020?gb=s  [Accessed: Jan. 30, 2025].


[3]     CPC Farnell,"Gravity Analogue Carbon Monoxide & Combustible Gas Sensor for Arduino-SEN0134”, CPC Farnell.[Online].Available:https://cpc.farnell.com/dfrobot/sen0134/analog-co-combustible-gas-sensor/dp/SC15111?st=mq7%20carbon%20monoxide. [Accessed: Jan. 30, 2025]. 


[4]      RS Components,"Seeed Studio Gear Stepper Motor Driver Pack for Desktop Printers, CNC Milling Machines", RS Components.[Online]. Available: https://uk.rs-online.com/web/p/power-motor-robotics-development-tools/1845109?gb=s. [Accessed: Jan. 30, 2025].


[5]        The Pi Hut, “2.7 E-Paper Display Module for Raspberry Pi Pico (264 x 176)”, The Pi Hut. [Online].Available: https://thepihut.com/products/2-7-e-paper-display-module-for-raspberry-pi-pico-264x176 . [Accessed: Jan. 30, 2025]. 


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