Portfolio C - Embedded Firmware Projects

This repository contains embedded firmware projects developed in C, demonstrating design patterns and architectures applied to embedded systems. Suggestions and contributions are always welcome.

Objective

Demonstrate practical experience in embedded firmware development:

• Low-level drivers for peripherals
• Design patterns applied to embedded systems
• Decoupled and portable architectures
• Maintainable and scalable code

Repository Structure

Each project is contained in its own directory as a Git submodule, allowing independent development and versioning.

Projects

1. Multi-Driver System: TCA8418 Keypad + TCA9554 I/O Expander

Directory: hardware_proxy_pattern/

System implementing Hardware Proxy pattern for managing multiple I2C peripherals on a shared bus. Includes driver for keypad matrix (TCA8418), I/O expander (TCA9554), keyboard manager with event queue, and BSP for ESP32-S3.

Components:

• TCA8418 Driver: Keypad scan controller (matrix up to 8x10, polling or interrupt detection, FIFO buffer 10 events)
• TCA9554 Driver: 8-bit I/O expander (individual pin control, input/output configuration, configurable polarity, multi-instance)
• Keyboard Manager: Asynchronous event management via FreeRTOS queue
• BSP: Hardware abstraction for portability (shared I2C, GPIO, interrupts)

Technical features:

• Hardware Proxy Pattern in both drivers
• Shared I2C bus (400 kHz Fast Mode)
• 4-layer architecture: Hardware → BSP → Driver → Manager/App
• FIFO queue for keyboard events
• Mutex synchronization (FreeRTOS)

Use cases: Industrial control panel, IoT devices with local interface, keypad access systems, GPIO expansion without MCU change.

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2. Pressure Monitoring System - Observer Pattern

Directory: observer_pattern/

Monitoring system implementing Observer pattern to decouple sensor data acquisition from processing. Multiple observers can subscribe to pressure changes without knowing each other.

Components:

• Pressure Sensor Driver: Mock driver for testing without hardware
• Pressure Manager: Observer pattern Subject, manages observer list (up to 3), converts raw values to engineering units
• Observers: UI observer (updates screen), Alarm observer (monitors thresholds), extensible to logging, network, etc.

Technical features:

• Observer Pattern (Subject-Observer)
• Context injection for private data per observer
• Dynamic attach/detach of observers
• FreeRTOS task for periodic reading (100ms)
• Automatic broadcast notification

Use cases: Monitoring systems with multiple consumers, dashboard with multiple views, alarm system, data logging, remote transmission.

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Implemented Design Patterns

• Hardware Proxy Pattern
• Observer Pattern
• State Machine Pattern (coming soon)
• Factory Pattern (coming soon)

Technology Stack

• Language: C (C99/C11)
• Architecture: ARM Cortex-M, ESP32-S3
• RTOS: FreeRTOS
• Protocols: I2C, UART, SPI
• Tools: GCC, Make, Git, ESP-IDF

Usage

Each project includes its own README with:

• Detailed API documentation
• Code examples
• Architecture diagrams
• Usage instructions

Download:

For each repository:

git submodule init
git submodule update

Or clone the entire project with submodules:

git clone --recursive git@github.com:grivera90/portfolio_c.git

Deployment

Uses Stable Mainline as Git branching model.

Future Updates

Upcoming projects:

• Communication protocols (MODBUS, CAN)
• State machines (FSM)
• Memory managers
• Drivers for sensors and actuators
• Additional RTOS examples

Author

Gonzalo Rivera

• GitHub: https://github.com/grivera90
• LinkedIn: https://www.linkedin.com/in/gonzalo-rivera-7072a262/
• Email: gonzaloriveras90@gmail.com

License

© 2025 grivera. All rights reserved.

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