Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit

ENGI4567-WE01/ ENGI44A10-WE01

Internet of Everything 4

2023

Question 1

(a) For monitoring the heating across a factory, a network of smart temperature sensors is installed. Each node has 5 temperature sensors connected to a microcontroller via an Inter- Integrated Circuit interface (I2C) bus. The different nodes in the overall network were then

connected to a central system using a single controlled area network (CAN) bus.

(i)   Sketch a diagram of the smart sensor, clearly showing all the  interfaces used by the Micro-controller unit (MCU). [5%]

(ii)  Explain (in your own words) what is the I2C bus, and using sketches, explain its operation. Explain the master/slave operation of the devices connected to the same I2C bus and the arbitration process if more than one masters want to transmit data at the same time. [20%]

(iii) Explain (in your own words) the advantages of using a differential bus (such as the CAN bus) in an environment with strong electromagnetic interferences. Illustrate a diagram of the CAN receiver.       [15%]

(iv) Explain (in your own words) the process of arbitration in the CAN bus, and how the device IDs can be used to prioritise the transmission of data.                       [10%]

(b) A smart humidity sensor is built by connecting the analogue output voltage of an electronic humidity sensor to the analogue-to-digital converter (ADC) embedded in a microcontroller (MCU). The strain is periodically sampled, and its digital value is sent elsewhere via a serial peripheral interface (SPI) bus. When the humidity is above a certain value, the MCU sets one

of its general-purpose inputs/outputs (GPIOs) to logic 1.

Assume the following parameters for this system:

•    The ADC has N = 16 bits, and effective bit number NEFF  = 14.2.

•    The ADC reference voltage is V REF  = 5 V.

•    The output voltage from the humidity sensor ranges from VL  = 1 V (@SL  = 10 %) to VH  = 4.5 V (@SH = 90 %).

(i)   Explain (in your own words), using diagrams, how the capacitive humidity sensor works to measure relative humidity? What are the three required peripherals to read from an analogue humidity sensor?     [8%]

(ii)  Explain (in your own words), using diagrams and graphs, what the quantisation noise is and derive an expression to compute the quantisation noise. Why is it convenient to introduce the concept of an effective bit number?                      [20%]

(iii) Assuming that the only noise in the system comes from the ADC, calculate the minimum change in the humidity that can be detected with a signal-to-noise ratio SNR = 20 dB. [12%]

(iv) Repeat the calculation in (ii) assuming the presence of further noise at the output of the humidity sensor, which is uniformly distributed with a peak-to-peak value of 1 mV. [10%]

Question 2

a)  i) Describe in 10 sentences or fewer an Internet of Things (IoT) application which demonstrates the value (e.g. economically, socially, environmentally or otherwise) of IoT systems.

ii) What are the four pillars of the Internet of Everything (IoE), and what interactions may occur in IoE systems?  For the application you identified in (i), give examples of these interactions if they exist.

iii) Describe in 10 sentences of fewer why standards (e.g. for the network or transport layer) play an important role in IoT/IoE systems. [46%]

b)  In your own words, describe the flooding, link state and distance vector routing protocols and their relative merits as applied to IoT applications.  Do not include diagrams with your answer.  What protocol would be most useful in networks where changes may occur from time to time? [14%]

c)  A sensor network is shown in Figure Q2.  The value alongside each connection represents the distance between the two sensors to be used to calculate the rank of the sensor.  The absence of an edge between two sensors indicates that the sensors are out of range for direct communication.  Assuming the Routing Protocol for Low Power and Lossy Networks (RPL), and that each node can only have one parent, construct the Destination-Oriented Directed Acyclic Graph (DODAG) for the sensor network shown in Figure Q2.  Show all your working. [40%]