CpE 3201 Premidterms Reviewer

Microcomputers: Composed of three basic components:
- CPU
- Memory
- I/O
- Designed for specific functions, often with real-time computing constraints.
Embedded Systems: A computer implemented for specific purposes, often operates independently of human intervention.
- Processing Cores: Microcontrollers (MCU) and Digital Signal Processors (DSP).
- Real-Time Response: Timeliness of response is crucial.

Apollo Guidance Computer: One of the early embedded systems developed at MIT.
Intel 4004: The first microprocessor designed for calculators and small systems.

Simple Control Loop: A basic architecture where software runs in loops calling subroutines managing hardware or software tasks.
Interrupt Controlled System: Triggered by external events; allows for more dynamic responses.
Cooperative Multitasking: Manages task switching based on timers; often includes an "operating system" kernel.
Microkernel: Allocates memory and CPU switching, with major functions handled in user mode.
Exokernel: Allows direct access to hardware by application programmers.
Monolithic Kernel: Complex structure similar to desktop operating systems like Linux or Windows.

Microcontroller: A small computer on an integrated circuit (IC) with CPU, memory, and I/O peripherals.
Harvard Architecture: Characterized by separate memory buses for concurrent instruction and data access.
Instruction Sets:
- RISC (Reduced Instruction Set Computer)
- CISC (Complex Instruction Set Computer)
  - CISC emphasizes hardware; has small code size with more cycles per second.
Economical Microcontrollers: They reduce size and cost by integrating CPU, memory, and I/O on a single chip.
Timers:
- Watch-Dog Timer (WDT): Resets the microcontroller during system failure.
Common Communication Interfaces: UART, I2C, SPI.
Limitations: Lack of a floating-point co-processor compared to general-purpose microprocessors.
Programming Languages:
- C Language: Most common for microcontroller programming.
- Assembly Language: Offers lower memory footprint and hardware abstraction.

Microcontroller Series: PIC16FXX series.
Programming Language: Primarily C.
CPU Architecture: RISC.
Instruction Set: 35 single-word instructions.
Operating Speed: Up to 20 MHz.
EEPROM Data Memory: 256 bytes.
Power Management:
- Brown-out Reset (BOR): Detects power drop and resets the MCU.
Timer1: A 16-bit timer functional in sleep mode.
10-bit ADC: Supports up to 8 channels.
Reset and Interrupt Vector Addresses:
- Reset Vector: 0000h
- Interrupt Vector: 0004h.
Watchdog Timer (WDT): Resets MCU upon program failure.
GPIO Ports:
- Total: 33 ports (PortA - 6, PortB - 8, PortC - 8, PortD - 8, PortE - 3).
TRISx Register: Configures I/O ports as input or output.
- Example Configuration:
  - Set all pins of PORTB as input: TRISB = 0xFF.
  - Set PORTB as output: TRISB = 0x00.
  - RB0 as input while others as output: TRISB = 0x01.

OPTION_REG: Controls weak internal pull-ups of PORTB.
PORTD: Commonly used for Parallel Slave Port (PSP) configuration.
PORTE: Contains three Schmitt Trigger input buffers for control inputs in parallel-slave mode.
PORTC: Multiplexed with USART communication (TX/RX).

Interrupt: A signal generated by external events, pausing current execution.
Interrupt Service Routine (ISR): Function executed upon interrupt occurrence.
Disadvantage: Can be confusing and error-prone without proper management.
GIE (Global Interrupt Enable): Enables or disables all unmasked interrupts.
Types of Interrupts: Maskable and Non-maskable interrupts.
RB0/INT Enablement: Requires setting the INTE bit in special function registers.
ISR Detection: Check INTF flag bit to detect RB0/INT interrupts.
Timer0: An 8-bit timer that generates overflow interrupts; sets TMR0IF flag on overflow.
ISR Management: Always disable GIE at beginning, re-enable at end.
ISR Prototype: Correct prototype in C: void interrupt ISR().