Computer vs Microcontroller
| Feature | Intel CPU | Microcontroller |
|---|---|---|
| Power | >95 W | ~0.25 W |
| Clock | ~5 GHz | ~4 MHz |
| Instructions | 1000+ | ~35 |
| Architecture | CISC | RISC |
| Purpose | Computing | Control |
Microcontrollers are complete systems on a chip. All components connect through a single bus: CPU, clock, RAM, ROM, I/O devices, analog peripherals, supervisory circuit, and power management.
Power Management
Can slow or stop the clock completely. Stopping the clock places the device into sleep or hibernate mode.
PIC
- Up to 20 MHz
- Up to 16 KB ROM
- ~500 B RAM
- 33 I/O pins
- Built-in ADC
- Memory cannot be expanded
Intel 8051
- 8-bit architecture
- 4 KB ROM
- 128 B RAM
- 32 I/O pins
- Can connect external memory
- No built-in ADC
AVR
Used in Arduino Uno (ATmega328).
- Internal clock
- 32 KB ROM
- 32 KB RAM
- 24 I/O pins
- Built-in ADC
AVR Internal Components
CPU core contains: ALU, registers, program counter, instruction decoder, and control unit.
Built-in peripherals:
- ADC
Converts analog signals to digital values. - Analog comparator
Compares two voltages. - USART
Serial communication. - SPI
Programming and communication. - Watchdog timer
Automatic recovery from software failures. - EEPROM
Permanent program storage. - JTAG
Debug interface.
ARM
- 32-bit architecture
- External RAM
- High performance
Examples: Raspberry Pi, modern embedded systems.
Debugging Constraints
IoT devices usually lack screens, keyboards, and direct debugging tools. Debugging typically requires JTAG or special external interfaces. Hardware development is often easier than software development for this reason.