NSC Electrical Technology Digital Introduction to Microcontrollers: 6.1 Explain how microprocessors

Question

6.1 Explain how microprocessors provide digital processing control to appliances.

They perform arithmetic and logic operations that make use of data on the chip in the form of the ROM program. It is this data that the microprocessor moves in sequential order from the ROM into the CPU to be processed, one-instruction-at-a-time, all controlled by an on-board clock.

As the process moves through its set sequence, data is often moved into and out of the RAM for short-term storage. When the sequence has ended, the CPU sends its final result to the I/O ports to be communicated out to the 'real world' and to control appliances.

6.2 FIGURE 6.2 below shows a CPU with registers as part of microcontrollers. Answer the questions that follow.

6.2.1 Label A to D in FIGURE 6.2.

A = Data from memory
B = Address for reading/writing data
C = Central Processing Unit (CPU)
D = Program counter

6.2.2 Explain the operating cycle of the CPU.

The operating cycle of a CPU follows a 'fetch-decode-execute' cycle. It first fetches instructions and data from memory. It then decodes the instructions which are given in binary code, and it executes the instruction before ending the cycle all over again.

6.3 Refer to registers within a CPU and explain the function of the following:

6.3.1 Memory address register (MAR).

The Memory Address Register (MAR) stores the address of the next instruction to be executed by the processor.

6.3.2 Program counter (PC).

The Program counter (PC) contains the address and status of the next instruction for processing and also informs the processor what the next instruction is that needs executing. It keeps track of the number of instructions that have been executed, adding one instruction each time.

6.4 State the function of the cache memory.

The CACHE memory is a 'short term memory that stores instructions and addresses' that are more often used, which saves time for the CPU.

6.5 Refer to FIGURE 6.5 of serial communication below and answer the questions on the next page.

6.5.1 State A and B.

A = Sender/Transmitter
B = Receiver

6.5.2 At point A the byte of data must be converted into a string of serial bits.

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Answer

At point A, the byte of data must be converted into a string of serial bits using a parallel-in - serial-out shift register.

6.6 State TWO advantages of the serial communication interface (SCI).

- Useful for communicating serial data.
- Easy and low-cost serial connection between two computer systems.

6.7 Refer to FIGURE 6.7 of the inter-integrated bus (i2C) and answer the questions that follow.

6.7.1 Label line X.

X = SDA (Serial data line)

6.7.2 State TWO disadvantages of the inter-integrated bus (i2C).

- i2C has slower speed.
- i2C draws more power.

6.7.3 State the function of pull-up resistors Rp.

The pull-up resistors Rp enable the i2C lines to go high.

6.7.4 Differentiate between the function of the master and the slave in FIGURE 6.7.

The master drives the SCL clock line and initiates a transfer of data over the i2C bus. The slaves respond to the master when instructed while one master can instruct many slaves.

6.8 Refer to the software of microcontrollers and explain the difference between an algorithm and a program.

An algorithm is a detailed step-by-step sequence of instructions that are followed to complete a task, or it can be described as a process that is followed in problem-solving operations or calculations. A program is a sequence of instructions that tells a computer how to do a task.

6.9 Study the following algorithm and complete its flow chart in FIGURE 6.9 on the ANSWER SHEET for QUESTION 6.9:

A monostable device has one stable state. It changes state when it is triggered by an input.

It stays in that state for five seconds. The output returns to its original state.

The device has a single output.

6.1 Explain how microprocessors provide digital processing control to appliances - NSC Electrical Technology Digital - Question 6 - 2023 - Paper 1

Worked Solution & Example Answer:6.1 Explain how microprocessors provide digital processing control to appliances - NSC Electrical Technology Digital - Question 6 - 2023 - Paper 1