Pico Access and Cloning System (PACS)

A compact embedded solution for secure credential cloning and local access control

info

Author: Abdulkadir Gobena DENBOBA
GitHub Project Link: https://github.com/UPB-PMRust-Students/proiect-denboba

Description

PACS (Pico Access and Cloning System) is a compact and cost-effective embedded system designed to facilitate secure credential cloning and local access control. Built on the Wi-Fi-capable Raspberry Pi Pico 2W, PACS serves as a versatile solution for managing physical access to secured environments such as residences, offices, and dormitories.

The system supports cloning of contactless smart cards (e.g., MIFARE Classic) and enables the configuration of authorized credentials for entry control. It can be used in two modes: User Mode acting ass access system or Admin Mode acting as cloning system. it can also be used with a smartphone giving users more convenience

Motivation

For my PM project, I wanted to work on a practical and real-world-relevant solution, and I could not find something more suitable for my level than PACS. In many institutions—such as student dormitories—each resident is issued a smart card to gain entry. Replacing or duplicating these cards is often costly (typically 20 RON per card) and time-consuming. PACS addresses this by allowing trusted users or administrators to securely clone authorized cards directly from the device and even use smartphones (via card emulation) as digital credentials with no cost. This not only saves time and money but also enhances convenience and security by eliminating unnecessary intermediaries.

Architecture

Schematic Diagram

Components and Connections

Raspberry Pi Pico and RC522 RFID Module (SPI Communication)

RFID (RC522)	Raspberry Pi Pico 2W	Notes
VCC	3.3V
GND	GND
RST	GP6	Reset(Optional)
SDA (SS)	GP5	SPI Chip Select
MOSI	GP3	SPI Data Out
MISO	GP4	SPI Data In
SCK	GP2	SPI Clock

note

The RFID module is used for reading and cloning card credentials. It communicates with the Raspberry Pi Pico via SPI. Raspberry Pi Pico is the main controller that manages the entire system.

Relay Module AND Raspberry Pi Pico

Relay Module	Raspberry Pi Pico 2W	Notes
IN	GP7	Activates solenoid
VCC	VSYS (5V)	Power for relay module
GND	GND	Common ground
NO (Normally Open)	Solenoid (-)	Activates lock when relay is triggered
COM (Common)	12V Power Source (-)	Shared ground for solenoid and relay
Flyback Diode	Across solenoid terminals	1N4007: Cathode → 12V+, Anode → GND

note

The relay module is used to control the solenoid lock. The Raspberry Pi Pico sends a signal to the relay to activate the lock.

Display Module and Raspberry Pi Pico (I2C Communication)

OLED (I2C)	Raspberry Pi Pico 2W	Notes
VCC	3.3V
GND	GND
SDA	GP16 (I^2C1)	Avoid GP0/GP1 (debug conflict)
SCL	GP17 (I^2C1)

note

The display module is used for user interaction and feedback. It communicates with the Raspberry Pi Pico via I2C.

Buzzer Module and Raspberry Pi Pico

Buzzer	Raspberry Pi Pico 2W	Notes
+	GP8
-	GND

note

The buzzer module provides audio feedback for various events in the system, such as successful cloning or access denial.

Push Button and Raspberry Pi Pico

Button	Raspberry Pi Pico 2W	Notes
User (GP12)	→ GND	Internal pull-up
Admin (GP13)	→ GND

note

The push button is used to switch between user and admin modes. The Raspberry Pi Pico uses internal pull-up resistors for the button inputs.

LED connection and Raspberry Pi Pico with resistor (PWM Control)

LED	Raspberry Pi Pico 2W	Purpose
Green	GP9 → 220Ω → GND	Access granted
Red	GP10 → 220Ω → GND	Access denied
Blue	GP11 → 220Ω → GND	Cloning mode(admin mode)

note

The LEDs provide visual feedback for different system states. The resistors limit the current to the LEDs to prevent damage.

power supply and Raspberry Pi Pico

Power Supply	Raspberry Pi Pico 2W	Notes
USB Cable	Micro-USB	5V (VSYS) + 3.3V logic power
12V Power Source	Solenoid Lock (+)	External 12V adapter/battery

note

The Raspberry Pi Pico is powered via a USB cable, while the solenoid lock requires a separate 12V power source.

Selenoid Lock connection

Solenoid Lock	Component	Note
(+)	12V Power Source	External 12V supply
(-)	Relay NO	Relay breaks ground (safety)
Flyback Diode	Across solenoid terminals	1N4007: Cathode → 12V+, Anode → GND

note

The solenoid lock is connected to the relay module, which controls its activation. The common ground is shared between the solenoid and the relay.

The system consists of two main functional modules:

• Cloning Module – Reads and replicates card credentials (UID-based).
• Access Control Module – Validates presented credentials and manages door lock mechanisms.

Core components are orchestrated via the Raspberry Pi Pico 2W and communicate through GPIO, I2C, and SPI interfaces.

Log

Week 5 - 11 May

In this initial phase, I focused on identifying and acquiring the essential components required for the project, as well as designing the initial system architecture. The key tasks accomplished during this phase are:

• Selected and acquired the necessary components
• Drafted the initial architecture and schematic diagrams
• Identified a potential software library for use in the project
• Documented the initial project structure

Week 12 - 18 May

In this phase, I concentrated on the hardware design and initial software setup. The key tasks accomplished during this phase are:

• Designed the PCB layout
• Tested the rgb led and buzzer modules
• Tested the relay module with the solenoid lock
• Tested the OLED display with the Raspberry
• Tested the RC522 RFID module with the Raspberry Pi Pico

Week 19 - 25 May

This week, I focused on software development and the integration of hardware components into the PACS (Pico Access and Cloning System). The main accomplishments include:

• Designed the overall PACS software architecture.
• Tested each hardware component individually using dedicated software (buzzer, LED, OLED, RFID).
• Integrated all components into a unified embedded software application.
• Developed the PACS mobile application in Flutter, with support for:
  • Reading RFID cards,
  • Emulating card behavior,
  • Communicating with the PACS system over the internet (TCP).
• Performed full system testing, ensuring reliable interaction between the mobile app and the embedded PACS system.

Hardware

Raspberry Pi Pico 2W

• Usage: Main controller
• Function: Processes all logic and manages peripherals

RC522 RFID Module

• Usage: Card reader
• Function: Reads/writes RFID card UIDs

5V Relay Module

• Usage: Lock controller
• Function: Switches 12V solenoid circuit

12V Solenoid Lock

• Usage: Door lock
• Function: Physically secures entry point

SSD1306 OLED Display

• Usage: User interface
• Function: Shows system status/messages

Active Buzzer

• Usage: Audio feedback
• Function: Signals operations/errors

RGB LEDs

• Usage: Visual indicators
• Function:
  • Green: Access granted
  • Red: Access denied
  • Blue: Cloning mode active

Tactile Buttons

• Usage: Mode selection
• Function: Toggle between user/admin modes

1N4007 Diode

• Usage: Circuit protection
• Function: Prevents voltage spikes

220Ω Resistors

• Usage: LED protection
• Function: Limits current to LEDs

MIFARE Classic Cards

• Usage: Test credentials
• Function: Authentication testing

Schematics

PCB Design

Bill of Materials

Device	Usage	Price
Raspberry Pi Pico W	Core microcontroller	35 RON
RC522 RFID Module	RFID card reading and cloning (via SPI)	10 RON
Solenoid Lock	Physical locking mechanism	34 RON
5V Relay Module	Controls power to solenoid lock	15 RON
Active Buzzer Module	Audio feedback for events	1 RON
LEDs (RGB)	Visual feedback for status	2 RON
Push Button	Mode switch (admin/user)	~1 RON
12V Duracell Battery + Holder	Power source for relay/lock	11 RON
1N4007 Diode	Flyback and polarity protection	0.5 RON
220Ω Resistors	Current limiting for LEDs	0.76 RON
OLED Display	Displays messages or status	15 RON
PCB Board	Board for mounting components	15 RON
RFID and NFC Cards	Cards used for unlocking system(15 cards )	11 RON

hardware connections

Software

note

Concepts from the laboratory that are used in the project are:

• PWM: For RGB LED control
• GPIO: For general-purpose input/output, including buttons, buzzers, and other peripherals
• I2C: For OLED display communication using SSD1306 driver
• SPI: For RC522 RFID module communication using mfrc522 driver
• Async: For network communication and task scheduling
• Wi-Fi: For wireless communication and remote access using cyw43 driver

Library	Description	Usage
embassy-rp	RP2350 Hardware Abstraction Layer	Mandatory for Pico W (GPIO, SPI, I2C, PWM)
cyw43	CYW43439 Wi-Fi driver for Pico W	Required for Wi-Fi connectivity
embassy-net	Async TCP/IP networking stack	Enables TCP socket communication
embassy-time	Async timers and durations	Used for task scheduling and delays
embassy-executor	Async runtime for embedded systems	Runs async tasks
embassy-sync	Async synchronization primitives (Mutex, Channels)	Thread-safe sharing between tasks
heapless	Stack-allocated collections (no_std)	Stores UIDs in Vec without dynamic allocation
defmt + defmt-rtt	Lightweight logging over RTT	Efficient debugging with minimal overhead
panic-probe	Crash logging with defmt integration	Graceful panic handling during development
mfrc522	MFRC522 RFID reader driver	Communicates with RC522 over SPI
embedded-hal-bus	Shared-bus wrapper for embedded-hal devices	Provides ExclusiveDevice for safe SPI access
embedded-graphics	2D drawing library for embedded displays	Renders text and graphics on OLED
ssd1306	I2C/SPI driver for SSD1306 OLED displays	Interfaces with the OLED screen
embedded-io-async	Async I/O traits	Async write to network or displays
static-cell	Safe static memory initializer	Used for globally safe singleton allocations

Links

1. pico.implrust.com
2. pacs repo
3. projects-2024