6.1 State TWO uses of a microcontroller as used in commercial devices - NSC Electrical Technology Digital - Question 6 - 2024 - Paper 1

The block diagram represents a microcontroller system which consists of a CPU, ROM, RAM, and input/output (I/O) interfaces.

The control bus is primarily used by the CPU to send control instructions to memory and I/O ports.

The data bus serves as the pathway for transferring data between the CPU, memory, and I/O devices, facilitating bidirectional communication.

An interface is a shared boundary where two separate components of a computer system exchange information.

Once data enters the Current Instruction Register (CIR) from the Memory Data Register (MDR), it is divided into two parts. The first part is decoded by the control unit for execution, while the second part indicates the address of the data that needs to be used with the instruction.

The accumulator is a storage register that holds data temporarily for arithmetic and logic operations, facilitating quick access and computation.

The two types of registers used within the CPU are:

1. General Purpose Register: Used for a variety of data manipulation tasks.
2. Special Purpose Register: Includes registers dedicated to specific functions, such as the Program Counter (PC) and the Memory Address Register (MAR).

Communication protocols are sets of rules that govern how data is transmitted and received between two electronic devices, ensuring reliable data exchange.

Simplex Communication is unidirectional, meaning data flows in only one direction from the transmitter to the receiver. In contrast, Half-Duplex Communication allows data transmission in both directions, but not simultaneously; devices take turns to communicate.

The Serial Peripheral Interface (SPI) operates through a synchronous serial communication method using separate lines for data input/output, and control signals, allowing for simultaneous data transfer.

The disadvantages of SPI include:

1. Susceptibility to Noise: Interference can disrupt communication.
2. Limited Distance: SPI can only operate over short distances, which can limit its application.

The maximum cable length for RS-485 communication is typically 1200 meters.

The mode of operation for RS-485 is typically simplex or half-duplex, allowing for data transmission in one direction at a time.

TWO devices that can be used with RS-485 include:

1. Point of Sale Terminals: Used for transaction processing.
2. CNC Machines: For precise automated control.

In the instruction cycle, the CPU retrieves a program instruction from memory, decodes the instruction, evaluates inputs, and then executes the instruction based on the decoded information.

The complete flow chart would start with a trigger event, checking if the switch is pressed. If pressed, it activates an output for five seconds before returning to the start. If not pressed, it loops back, continually checking for input.