Here’s a fully detailed, embedded-engineer–level Markdown README combining all technical depth, architecture, timing, data formats, hardware specifics, and operational flow from your original summary and the README draft. It’s tailored for low-level embedded debugging, performance review, and system understanding:

Automatic Cruise Speed Control Using LPC2148 (Proteus Simulation)

Overview

This automotive-grade Cruise Control system is implemented on the LPC2148 ARM7 MCU (60 MHz, 32 KB RAM, 512 KB Flash) and simulated in Proteus v8.12. It provides real-time speed regulation based on analog distance sensing with calibrated control and robust data logging.

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System Features & Technical Highlights

1. Analog Distance Sensing & Calibration

• Input Source: 10-bit ADC channel 0.3 sampling at 20 kHz
• Signal Conditioning: 4-tap moving average filter reducing noise by ~30 mV RMS
• Calibration Method: Software routine using 5 reference points, achieving ±2% measurement accuracy
• Calibration Data Storage:
  • EEPROM layout stores 4 calibration profiles × 5 points each
  • Each profile: 5 points × 8 bytes = 40 bytes
  • Total EEPROM usage for calibration: 160 bytes
• Distance Mapping: Linear interpolation via 128-entry lookup table (distance_map.c)

2. Exponential PWM Speed Ramping

• PWM Generation: Timer1 configured for 10 kHz output (Prescaler=60, MR0=1000)
• Output Pin: P0.5 controlling L293D motor driver
• Speed Update Logic:

  delta = (target_speed - current_speed);  
  current_speed += delta * 0.15;  // ~4 second ramp for 40 to 80 km/h  

• ISR Frequency: 50 ms intervals, CPU utilization ~2.5%
• Ensures smooth, gradual acceleration/deceleration avoiding abrupt changes

3. I²C-Based Black Box Logging

• EEPROM: 24LC64 at 100 kHz I²C bus speed
• Data Entry Format (8 bytes per record):
  • Timestamp: 2 bytes (milliseconds or ticks)
  • Mode: 1 byte (ACC state)
  • Speed: 1 byte (km/h)
  • Distance: 2 bytes (ADC or calibrated units)
  • Flags: 2 bytes (system events, errors, hysteresis triggers)
• Buffer Management:
  • 8 KB circular buffer (~1000 entries) in EEPROM
  • Wear leveling implemented with 32-byte page rotation for endurance
• Diagnostics: External master device can read logs over I²C

4. Failsafe & Diagnostic Measures

• Automatic shutdown if:
  • Distance < 10 cm (critical proximity)
  • Speed < 40 km/h (minimum safe speed)
• Hysteresis band of ±5 ADC counts to avoid false triggers from sensor noise
• Exit codes and system flags logged in EEPROM for post-mortem analysis

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Firmware Architecture & Modules

• adc_driver.c: ADC burst sampling + 4-tap moving average filter executed in a 50 µs ISR
• distance_map.c: Implements linear interpolation on 128-point calibrated LUT for distance conversion
• pwm_control.c: Timer and PWM initialization; implements exponential speed ramp logic
• eeprom_log.c: I²C driver with circular buffer, wear leveling, and error detection
• main_loop.c: State machine for ACC operation, including calibration UI controlled via SW2–SW4 buttons
• ISR Priorities: ADC ISR highest priority; I²C logging and PWM control ISRs lower priority to maintain real-time responsiveness

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Hardware Overview

Component	Description
MCU	LPC2148 (ARM7, 60 MHz)
ADC	10-bit, sampling ADC0.3 @ 20 kHz
PWM Output	Timer1, 10 kHz PWM on P0.5
Motor Driver	L293D
Distance Sensor	Analog photodiode sensor
EEPROM	24LC64 I²C EEPROM, 8 KB
LCD	16×2 character LCD for UI
Buttons	SW1–SW4 for UI interaction
Buzzer	User feedback signals
UART	USB-to-UART converter for debug
Power Consumption	25 mA idle → 45 mA active

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Performance Metrics

Metric	Value
ADC to PWM latency	≤ 150 ms
CPU Utilization (PWM ISR)	~2.5%
EEPROM Log Endurance	Tested 10,000+ write cycles
Stack Usage	< 128 bytes
RAM Usage	~3.5 KB
Flash Code Size	~24 KB
Power Consumption	25–45 mA depending on mode

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User Interface & Operation

1. Parameter Setup Mode:
   • Press SW1 to enter speed/distance settings
   • Use SW2 to toggle parameters (even press = speed, odd = distance)
   • Adjust with SW3 (increment) and SW4 (decrement)
2. Save & Start ACC:
   • Press SW1 to confirm parameters and store in EEPROM
   • Press SW1 again to activate ACC mode
3. ACC Operation:
   • Real-time speed adjusted via exponential PWM ramping based on measured distance
   • LCD updates current speed and distance data continuously
4. Failsafe Shutdown:
   • Press SW1 to stop ACC mode manually
   • Auto-disable with beep if speed < 40 km/h or distance < 10 cm
5. Diagnostics:
   • UART logs and EEPROM black box available for troubleshooting

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Project Directory Layout

/project-root ├─ src/ # C source files for LPC2148 firmware ├─ simulation/ # Proteus simulation project files ├─ docs/ # Documentation and manuals ├─ README.md # Project description and usage ├─ LICENSE # MIT License file

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Contribution Guidelines

• Fork the repo
• Create feature or bugfix branch
• Implement and test changes thoroughly
• Submit a pull request with detailed description

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Acknowledgments & References

• Proteus Simulation
• LPC2148 Development Board - NXP
• EEPROM Datasheet: Microchip 24LC64
• Motor Driver: L293D Datasheet

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Contact

Questions or collaboration proposals: Your Name

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Visuals