Cyber-Physical Systems Projects

A collection of embedded systems and digital design projects focused on Raspberry Pi hardware interfacing, sensor communication, MQTT-based networking, GPIO/PWM control, FPGA-based digital logic, and SystemVerilog hardware design.

This repository demonstrates practical cyber-physical systems development across the full stack: physical sensors, embedded software, communication protocols, networked data publishing, remote device control, digital logic, state machines, and FPGA-to-Raspberry Pi hardware communication.

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Overview

Cyber-physical systems connect computation, sensing, communication, and physical-world behavior. This repository documents a series of projects built around that idea using Raspberry Pi, Python, I2C, SPI, MQTT, GPIO/PWM, SystemVerilog, Vivado, and the Basys3 FPGA.

The projects begin with Raspberry Pi setup and remote development, then move into sensor driver development, real-time sensor publishing, remote LED control, combinational logic, arithmetic logic design, finite state machines, and FPGA-to-Raspberry Pi SPI communication.

This repository was cleaned and reorganized from private coursework into a public portfolio project to better show embedded systems, hardware-software integration, and digital design skills.

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Project Goals

• Build reliable embedded systems using Raspberry Pi and external hardware
• Interface with sensors using I2C and SPI communication protocols
• Convert raw sensor register data into usable physical measurements
• Publish live sensor data over MQTT for remote monitoring
• Control physical outputs using GPIO and PWM
• Design and verify digital hardware using SystemVerilog
• Implement combinational and sequential logic circuits
• Build finite state machines for real-world control systems
• Connect FPGA logic with external embedded devices
• Practice structured embedded development using Git and GitHub

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Technical Areas

Area	Description
Embedded Linux	Raspberry Pi setup, SSH access, command-line development, and Git workflow
Sensor Interfacing	Low-level communication with pressure, temperature, and accelerometer sensors
I2C Communication	Register-level driver development for the LPS331AP pressure/temperature sensor
SPI Communication	Register-level accelerometer communication and FPGA-to-Raspberry Pi SPI transfer
MQTT Networking	Publishing sensor data and subscribing to remote control messages
GPIO / PWM Control	LED control using duty cycle and frequency updates
Digital Logic	Decoder, demultiplexer, ALU, counter, and combinational logic design
Sequential Logic	Flip-flops, registers, state retention, and clocked hardware behavior
Finite State Machines	Elevator controller design using state-based control logic
FPGA Integration	Basys3 hardware demonstrations, switches, LEDs, buttons, and 7-segment displays

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Repository Structure

cyber-physical-systems-projects/
│
├── project-00-raspberry-pi-setup-and-git/
│   └── Raspberry Pi setup, SSH workflow, and GitHub development workflow
│
├── project-01-lps331ap-i2c-pressure-temperature-sensor/
│   └── I2C driver for pressure and temperature measurements
│
├── project-02-adxl343-spi-accelerometer/
│   └── SPI driver for 3-axis acceleration data acquisition
│
├── project-03-mqtt-sensor-network-node/
│   └── MQTT-connected sensor node for publishing live sensor data
│
├── project-04-mqtt-led-control/
│   └── Remote LED control using MQTT, GPIO, and PWM
│
├── project-05-systemverilog-3-to-8-demultiplexer/
│   └── Decoder-based 3-to-8 demultiplexer with SystemVerilog testbenches
│
├── project-06-systemverilog-8-bit-arithmetic-logic-unit/
│   └── 8-bit ALU supporting arithmetic, logic, carry, and overflow behavior
│
├── project-07-systemverilog-2-bit-saturating-counter/
│   └── SystemVerilog RTL design and verification of a 2-bit saturating counter
│
├── project-08-systemverilog-elevator-control-state-machine/
│   └── 4-floor elevator controller using FSM logic and 7-segment display output
│
├── project-09-basys3-raspberry-pi-spi-interface/
│   └── SPI communication link between a Basys3 FPGA and Raspberry Pi
│
└── README.md

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Projects

Project 00 — Raspberry Pi Setup and Git Workflow

This project establishes the development foundation for the rest of the repository. It focuses on setting up a Raspberry Pi, enabling SSH-based remote access, configuring wireless networking, and using Git/GitHub for version control.

Key Work

• Connected to a Raspberry Pi using SSH
• Configured a remote embedded development workflow
• Practiced repository cloning, commits, pushes, and pulls
• Established a repeatable workflow for later hardware projects

Skills Demonstrated

• Raspberry Pi setup
• Linux command-line usage
• SSH remote development
• Git and GitHub workflow

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Project 01 — LPS331AP I2C Pressure and Temperature Sensor

This project implements a Python driver for the LPS331AP pressure and temperature sensor using I2C communication on a Raspberry Pi.

Key Work

• Communicated with the sensor using the smbus library
• Verified the device using the WHOAMI register
• Configured sensor control registers
• Read raw pressure and temperature values from sensor registers
• Converted raw binary data into physical units

Skills Demonstrated

• I2C communication
• Register-level sensor configuration
• Embedded Python development
• Raw data conversion
• Hardware-software integration

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Project 02 — ADXL343 SPI Accelerometer

This project develops a Python-based SPI driver for the ADXL343 accelerometer. The system reads X, Y, and Z acceleration values from the sensor and converts the raw register data into usable acceleration measurements.

Key Work

• Communicated with the accelerometer using the spidev library
• Configured SPI mode for device communication
• Verified the sensor using the DEVID register
• Enabled measurement mode
• Read and converted X, Y, and Z acceleration data

Skills Demonstrated

• SPI communication
• Binary data handling
• Sensor driver development
• Multi-axis data acquisition
• Embedded Python programming

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Project 03 — MQTT Sensor Network Node

This project combines pressure, temperature, and acceleration sensing into a network-connected MQTT sensor node. The Raspberry Pi publishes live sensor data to a broker at fixed time intervals.

Key Work

• Integrated LPS331AP pressure/temperature data
• Integrated ADXL343 accelerometer data
• Published sensor readings using MQTT
• Sent data to structured MQTT topics
• Built a simple remote monitoring pipeline

Example MQTT Topics

sensors/<id>/temperature
sensors/<id>/pressure
sensors/<id>/accel/x
sensors/<id>/accel/y
sensors/<id>/accel/z

Skills Demonstrated

• MQTT publish/subscribe architecture
• Networked embedded systems
• Real-time sensor data streaming
• Sensor integration
• Cyber-physical system communication

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Project 04 — MQTT LED Control with PWM

This project extends the MQTT sensor node by adding remote LED control through GPIO and PWM. The Raspberry Pi subscribes to MQTT control topics and updates LED behavior based on incoming messages.

Key Work

• Developed a custom LED driver
• Controlled LED duty cycle using PWM
• Updated LED frequency dynamically
• Subscribed to MQTT control topics
• Combined sensing, publishing, and actuation in one system

Example MQTT Control Topics

sensors/<id>/led/duty
sensors/<id>/led/frequency

Skills Demonstrated

• GPIO control
• PWM signal generation
• MQTT subscriptions
• Remote actuator control
• Embedded systems integration

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Project 05 — SystemVerilog 3-to-8 Demultiplexer

This project implements a 3-to-8 decoder and uses it as a submodule to build a 3-to-8 demultiplexer in SystemVerilog. The design demonstrates combinational logic, one-hot decoding, module instantiation, enable-controlled output routing, and testbench-based verification.

Key Work

• Designed a 3-to-8 decoder using Boolean logic
• Built a 3-to-8 demultiplexer using the decoder as a submodule
• Used internal wires to connect decoder outputs to demultiplexer logic
• Gated demultiplexer outputs using an enable signal
• Verified all decoder and demultiplexer input combinations with testbenches

Skills Demonstrated

• SystemVerilog combinational logic
• Boolean expression design
• Decoder implementation
• Demultiplexer implementation
• Module instantiation
• Testbench tasks
• Assertion-based verification
• FPGA-oriented digital design

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Project 06 — SystemVerilog 8-Bit Arithmetic Logic Unit

This project implements an 8-bit Arithmetic Logic Unit (ALU) in SystemVerilog. The ALU performs arithmetic and logical operations on two 8-bit operands and produces an 8-bit result, an unsigned carry flag, and a signed overflow flag.

Key Work

• Designed an 8-bit ALU using SystemVerilog
• Implemented arithmetic operations including addition and subtraction
• Implemented logical operations including AND, OR, NOT, and XOR
• Added transfer and zero-test operations
• Used a 4-bit select signal to control ALU behavior
• Detected unsigned carry for arithmetic operations
• Detected signed overflow for addition and subtraction
• Verified ALU behavior using a dedicated testbench

Supported Operations

Select s	Operation	Result
1110	AND	r = a & b
1101	OR	`r = a
1100	NOT	r = ~a
1011	XOR	r = a ^ b
1010	Addition	r = a + b
1001	Subtraction	r = a - b
1000	Transfer	r = a
0111	Test	r = (a == 0)

Skills Demonstrated

• ALU design
• Arithmetic logic implementation
• Bitwise logic operations
• Carry detection
• Signed overflow detection
• always_comb design
• case statement operation selection
• Testbench development
• Digital hardware verification

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Project 07 — SystemVerilog 2-Bit Saturating Counter

This project transitions from embedded software into digital hardware design. It implements a 2-bit saturating counter in SystemVerilog and verifies its behavior using a testbench.

The counter increments and decrements based on an input signal but saturates at its limits instead of overflowing or underflowing.

Key Behavior

• Counts from 0 to 3
• Saturates at 3 when incremented past the maximum value
• Saturates at 0 when decremented past the minimum value
• Supports reset, enable, and direction control signals

Skills Demonstrated

• SystemVerilog RTL design
• Sequential logic design
• always_ff implementation
• Testbench development
• Assertion-based verification
• FPGA-oriented design practices

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Project 08 — SystemVerilog Elevator Control State Machine

This project implements a 4-floor elevator simulator using SystemVerilog. The design uses a finite state machine to control elevator movement, door behavior, floor selection, and visual output on the Basys3 FPGA 7-segment displays.

Key Work

• Designed a finite state machine for a 4-floor elevator system
• Handled floor request button inputs
• Stored the first requested floor until the elevator reached it
• Ignored additional requests while servicing the current request
• Reset the elevator to floor 1 with the door open
• Created a 7-segment display driver for floor and door visualization
• Used active-low display logic for the Basys3 board
• Verified the elevator controller and display driver using testbenches

System Behavior

Floor Request
      │
      ▼
Store Destination
      │
      ▼
Close Door
      │
      ▼
Move Up or Down
      │
      ▼
Arrive at Requested Floor
      │
      ▼
Open Door

Skills Demonstrated

• Finite state machine design
• Sequential logic implementation
• State-based output control
• Reset handling
• Input request handling
• 7-segment display driving
• Active-low logic design
• SystemVerilog always_ff and always_comb
• FPGA-oriented control system design
• Simulation-based verification

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Project 09 — Basys3 to Raspberry Pi SPI Interface

This project implements a Serial Peripheral Interface (SPI) communication link between a Basys3 FPGA and a Raspberry Pi. The Raspberry Pi acts as the SPI master, while the Basys3 FPGA acts as the SPI slave.

The design allows the Raspberry Pi to read switch values from the Basys3 and write LED values back to the FPGA using a simple SPI-based register interface.

Key Work

• Implemented an SPI slave interface in SystemVerilog
• Captured incoming MOSI data on the rising edge of SCLK
• Updated outgoing MISO data on the falling edge of SCLK
• Converted serial SPI data into 8-bit parallel data
• Built a controller interface for reading switches and writing LEDs
• Implemented a register-mapped read/write interface
• Connected Raspberry Pi SPI communication to Basys3 FPGA hardware

Register Address Map

Address	Mapping	Access Type
7'h00	chip_id	Read-only
7'h01	switches[7:0]	Read-only
7'h02	switches[15:8]	Read-only
7'h03	leds[7:0]	Read/write
7'h04	leds[15:8]	Read/write

Skills Demonstrated

• SPI slave interface design
• Serial-to-parallel data conversion
• Parallel-to-serial data transmission
• Edge-sensitive signal handling
• FPGA register interface design
• Address decoding
• Read/write transaction handling
• Raspberry Pi to FPGA communication
• Basys3 switch and LED integration
• Hardware/software co-design

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System-Level Flow

Embedded Sensor and MQTT Projects

Physical Sensors / Outputs
        │
        ▼
Raspberry Pi GPIO / I2C / SPI Interfaces
        │
        ▼
Python Sensor Drivers and Control Logic
        │
        ▼
MQTT Publish / Subscribe Communication
        │
        ▼
Remote Monitoring and Remote Device Control

Digital Design and FPGA Projects

SystemVerilog RTL
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        ▼
Simulation and Testbench Verification
        │
        ▼
Vivado Synthesis / FPGA Implementation
        │
        ▼
Basys3 Hardware Demonstration

FPGA-to-Raspberry Pi SPI Project

Raspberry Pi SPI Master
        │
        ▼
SPI Signals: SCLK, MOSI, MISO, SS
        │
        ▼
Basys3 SPI Slave Interface
        │
        ▼
Controller Register Interface
        │
        ├── Read Switches
        ├── Write LEDs
        └── Return Chip ID

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Tools and Technologies

Languages

• Python
• SystemVerilog

Hardware

• Raspberry Pi 3B
• LPS331AP pressure/temperature sensor
• ADXL343 accelerometer
• LED circuit
• Basys3 FPGA
• 7-segment displays
• Switches and pushbuttons

Protocols and Interfaces

• I2C
• SPI
• MQTT
• GPIO
• PWM

Libraries and Tools

• smbus
• spidev
• paho-mqtt
• Vivado
• Git / GitHub
• Linux command line
• FPGA simulation tools

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Skills Demonstrated

• Embedded Python development
• Raspberry Pi hardware interfacing
• Sensor driver design
• I2C and SPI protocol implementation
• Low-level register manipulation
• MQTT-based network communication
• Real-time sensor data publishing
• GPIO and PWM control
• Remote actuator control
• Hardware-software integration
• SystemVerilog RTL design
• Combinational logic design
• Sequential logic design
• Finite state machine design
• ALU design
• SPI slave interface design
• Testbench development
• Assertion-based verification
• FPGA-oriented system design
• Cyber-physical systems architecture

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Why This Project Matters

This repository shows the foundation of cyber-physical systems engineering: connecting software to real hardware, reading physical data from sensors, transmitting that data over a network, and controlling outputs remotely.

It also connects embedded systems with digital hardware design. The Raspberry Pi projects demonstrate software-driven interaction with physical sensors and actuators, while the SystemVerilog projects demonstrate hardware-level logic design, state machines, FPGA communication, and digital verification.

Together, these projects demonstrate practical experience with the kinds of systems used in robotics, IoT, automation, embedded platforms, intelligent devices, and FPGA-based hardware systems.

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Author

Jaiden Medina
Computer Engineering @ Indiana University
Accelerated M.S. in Intelligent Systems Engineering

• GitHub: jfmedina05
• Portfolio: www.jaidenmedina.com
• LinkedIn: jaiden-medina