Define the term microcontroller - NSC Electrical Technology Digital - Question 5 - 2019 - Paper 1

The Current Instruction Register (CIR) holds the instruction that is currently being executed at a specific address in memory. It is crucial for the execution process as it stores the instruction and works closely with the CPU to ensure that the correct operations are performed.

The purpose of an analogue-to-digital converter (ADC) is to convert an analogue signal into a digital signal. It detects a continuously variable (analogue) signal and changes it into a digital format that can be processed by a microcontroller or digital system.

The timer functions by accepting data one bit at a time, controlled by the pulse rate of the clock. It increments the count within the Count Register on each clock pulse until the register overflows. Once the counting is complete, the register is cleared for the next cycle, allowing continuous timing operations.

The RAM stores all data required by the CPU during program execution. It can read and write data, holding operational programs and data instantaneously needed for processing.

The two methods of sending data include:

1. Simplex - Data is transmitted in one direction only.
2. Duplex - Data can be sent and received simultaneously.

Parallel communication offers several advantages, including faster data transfer rates as multiple bits are sent simultaneously, and increased bandwidth, allowing more information to be transmitted in a shorter time.

The disadvantages of synchronous communication include the requirement of a clock signal, which can lead to complications if the master and slave devices are not synchronized, and it can be less flexible compared to asynchronous methods.

The I²C bus is a powerful two-wire communication system that allows multiple devices to communicate over a single bus. It operates on a master-slave principle, where the master device controls the timing and the flow of data between itself and multiple slaves. The use of only two lines—Serial Clock Line (SCL) and Serial Data Line (SDA)—simplifies connections and reduces wiring complexity.

Block A is labeled as 'Master'.

SCL stands for Serial Clock Line.

The pull-up resistors are necessary for maintaining the integrity of the signals on the SCL and SDA lines. They pull the lines high to a +5 V supply when no device is driving the line low, ensuring reliable operation.

One characteristic of the slave is that it cannot initiate a transfer on the I²C bus; it only responds to requests initiated by the master.

Three advantages of the I²C bus include:

1. It requires only two wires for communication, reducing wiring complexity.
2. It is cheaper to implement than other communication protocols like SPI.
3. It supports multiple master devices, enabling a flexible communication network.

The operating voltage for logic '1' is typically +3V to +15V, while for logic '0' it is usually 0V to +0.8V.

Three applications of the RS-232 communication protocol include:

1. Printers
2. Modems
3. Data projectors

A program is a sequence of instructions that informs a computer how to perform a specific task.

A flow diagram is a visual representation of the steps and decisions required to perform and complete a process.

The flow diagram would start with the sensor monitoring the door. If the sensor is activated, the alarm will sound. From there, a decision branch checks if the reset button is pressed. If reset is pressed, the alarm will turn off; if not, the alarm continues to sound.