Environment monitoring System has wide prospects of application in fields both domestic and industrial. Controlling temperature, humidity, and detecting smoke and other hazardous gases, each of them is an essential aspect of a comfortable home and a safe workplace.
A subsystem to detect temperature and carbon dioxide levels in the environment via using a Field Programmable Gate Array (FPGA) can be developed. FPGA system has an advantage over generic microprocessors and microcontrollers, as it can be reprogrammed to serve different functions at different times. Further, it has better multitasking capabilities and can process separate streams of data simultaneously and can keep up with rapidly changing input conditions.
Components and Method
Two sensors are used, LM35DZ Temperature Sensor and MQ135 Gas Sensor to carry out the project. Of these two, LM35DZ provides a linear output proportionate to the temperature in Celsius. MQ135 delivers a linear output against the concentration of Carbon Dioxide in the atmosphere.
The outputs from the sensors are fed into the ADC, which converts the analog signals into digital signals. The ADC0809CCN has 8 analog input pins, which can be converted to an 8-bit digital output. It uses a 256R resistance ladder together with a switch tree, the signal from which is passed through successive approximation registers, and finally through a comparator. The ADC performs n-iterations to provide the output for an n-bit converter, which in this case, is 8.
ADC0809CCN Pin Diagram
The accuracy of the output is dependent upon the comparator, which is a chopper-stabilized comparator that converts the DC input signal into the AC signal and amplifies it before the DC level is restored. Such a procedure limits the drift component of the amplifier and enhances the accuracy of the whole system.
The output from the ADC is fed into the digital input ports of the ZYBO Z7-10 FPGA board. The digital data values are compared against pre-programmed data values encoded as a look-up table. The use of FPGA allows for a comparison of hundreds of data points and performs a fundamental transformation of digital input back into environmental data.
ZYBO Z7-10 FPGA Board
For a system with multiple sensors attached, an FPGA board acts as a better alternative, as it can take in all input channels and update them simultaneously on the clock-edge, rather than go through them one by one. This allows for faster response and more efficient systems to be utilized.
The final display is done via a 16*2 character LCD module, the Pmod CLP. The Digilent Pmod CLP LCD is a 12-pin peripheral module with 8 I/O signal pins, two ground pins, and two power pins.
Further development of this project can proceed in multiple ways, including, but not limited to, improvement of fidelity by increasing the resolution of the ADC and integrating the ADC with the FPGA board to prevent loss due to external interfacing.
The FPGA board has the ability to handle multiple parallel data streams and a massive amount of processing, which makes it ideal for intensive computational tasks like image recognition, which could be a further aspect of this project.
Practical Application of EMS
The video demonstrates the use of Environment monitoring Systems in the field of cleanroom and pharmaceutical manufacturing environments to ensure the cleanliness of an area.
What to learn more about EMS?
Download the pdf (An Environment monitoring system with integrated wired and wireless sensors) here.
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