Answer

Correct option: (iv) Hard Disk

Explanation

A typical microcontroller integrates essential computing and control resources on a single chip, such as:

• CPU: Executes program instructions.
• RAM: Temporarily stores variables and runtime data.
• I/O ports: Interface with sensors, actuators and external devices.
• Timers/counters: Generate timing functions and count events.
• Peripherals: May include ADC, communication interfaces, PWM and other modules.

A hard disk is a separate mass-storage device and is not normally an integrated component of a microcontroller.

Therefore, the correct answer is (iv).

Answer

Correct option: (ii) Internal clock pulses

Explanation

A timer in a microcontroller is generally driven by the internal system clock or a clock derived from it. It increments its count at regular intervals and is used for generating delays, measuring time intervals, scheduling tasks and producing periodic events.

A counter can instead be configured to count external events or pulses.

Example

If a timer receives a 1 MHz clock, one clock period is:

$$T = \frac{1}{1\,MHz} = 1\,\mu s$$

The timer can therefore measure time by counting these clock periods.

Therefore, the correct answer is (ii).

Answer

Correct option: (ii) Simple and fast instructions

Explanation

RISC (Reduced Instruction Set Computer) microcontrollers use a relatively small and simple instruction set. Instructions are designed to execute efficiently, often in a small number of clock cycles.

Main characteristics of RISC

• Small and simple instruction set.
• Fast instruction execution.
• Large or efficient register usage.
• Simple instruction formats.
• Efficient pipelining in many architectures.
• Suitable for embedded real-time applications.

This approach makes the processor easier to implement and can provide high performance for a given clock frequency.

Therefore, the correct answer is (ii).

Solution: Microcontroller Architecture, Assembly and C Programming

Microcontroller Architecture

A microcontroller is a compact integrated circuit containing a processor, memory, I/O and peripherals for embedded control applications.

              ┌─────────────────────┐
              │        CPU          │
              │ ALU + Control Unit  │
              │ Registers           │
              └──────────┬──────────┘
                         │ System Bus
        ┌────────────────┼────────────────┐
        ↓                ↓                ↓
   Program Memory    Data Memory       I/O Ports
   Flash/ROM         RAM/EEPROM        GPIO
        │                │                │
        └────────────────┼────────────────┘
                         ↓
              Timers / Counters
              ADC / PWM / DAC
              SPI / I²C / UART

Major blocks

• CPU: Executes instructions.
• ALU: Performs arithmetic and logical operations.
• Registers: High-speed temporary storage.
• Program memory: Stores firmware.
• RAM: Stores temporary variables and stack data.
• EEPROM/Flash: Stores non-volatile data or program code.
• GPIO: Interfaces with external sensors and actuators.
• Timers/Counters: Generate delays and measure/count events.
• ADC/DAC/PWM: Interface between digital electronics and analog systems.
• Communication peripherals: SPI, I²C, UART/USART and others.

Assembly Language Programming

Assembly language uses processor-specific mnemonics representing machine instructions.

Example:

MOVLW 05H
MOVWF COUNT
INCF  COUNT, F

The exact instructions depend on the microcontroller architecture.

Advantages

• Precise hardware control.
• Efficient execution.
• Small and predictable code.

Limitations

• Difficult to write and maintain for large applications.
• Processor-specific.

C Language Programming

C provides structured, readable programming while still allowing direct hardware control through registers, pointers and bit operations.

Example:

#include <stdint.h>

int main(void)
{
    uint8_t count = 0;
    while (1)
    {
        count++;
    }
}

In practical firmware, initialization functions configure clocks, GPIO, ADC, timers and communication peripherals before the main loop executes.

Assembly vs C

Feature	Assembly	C
Readability	Low	High
Hardware control	Very direct	Direct through registers/APIs
Portability	Low	Higher
Development time	Longer	Shorter
Optimization	Can be highly optimized	Compiler-dependent

Conclusion

A microcontroller combines processing, memory and peripherals in one device. Assembly provides low-level control, while C provides a practical balance of performance, readability and portability for embedded DAQ applications.

Solution: ADC and DAC in a Microcontroller System

ADC: Analog-to-Digital Converter

An ADC converts an analog voltage into a digital code that a microcontroller can process.

Working

Analog Sensor → Signal Conditioning → ADC → Digital Code → CPU

1. The analog signal is applied to the ADC input.
2. The ADC samples the signal.
3. The input range is divided into discrete levels.
4. The nearest digital code is generated.
5. The microcontroller reads the code and converts it into engineering units.

For an ideal $n$-bit ADC with input range $V_{FS}$:

$$LSB = \frac{V_{FS}}{2^n}$$

Approximately, the ADC code is:

$$Code \approx \frac{V_{in}}{V_{FS}}(2^n-1)$$

Example

For a 10-bit ADC with 0–5 V input:

$$LSB \approx \frac{5}{1024}=4.883\text{ mV}$$

DAC: Digital-to-Analog Converter

A DAC converts a digital number generated by the microcontroller into an analog voltage or current.

CPU → Digital Code → DAC → Analog Voltage → Actuator

For an ideal $n$-bit voltage DAC with reference $V_{ref}$:

$$V_{out}\approx\frac{Code}{2^n-1}V_{ref}$$

The exact transfer equation depends on the DAC architecture and datasheet conventions.

Applications

• ADC: temperature, pressure, light and biomedical sensors.
• DAC: waveform generation, motor control references, audio and analog actuator control.

ADC vs DAC

Feature	ADC	DAC
Conversion	Analog → Digital	Digital → Analog
Input	Voltage/current	Digital code
Output	Digital code	Analog voltage/current
Use	Measurement	Control/output generation

Conclusion

ADC enables the microcontroller to measure the physical world, while DAC enables it to generate controlled analog outputs.