PCB Design for Modular 16x MFRC522 RFID Sensor Array (with Buffering, Power Management, and Signal Integrity)
Budget: €30 – €250 EUR
We are seeking an experienced PCB designer to develop a robust, production-ready modular PCB for a 16x MFRC522 (mini version) sensor array, optimized for SPI operation, signal integrity, and easy system expansion.
The project requires best practices in power distribution, EMI/EMC layout, and flat, stackable module integration, suitable for multi-board scalable sensing applications.
Background:
Each PCB module will host 16 MFRC522 (mini, pin-header type, stacked as flat as possible) RFID readers, communicating via SPI with a plug-in microcontroller (STM32 or ESP32 preferred).
The system is designed for up to four such sensor arrays working in parallel, each connecting to a master controller via I2C or UART (addressable per board).
Requirements include robust power supply, professional signal buffering, strict copper keepout under RFID antennas, and clear mechanical design for compact stacking.
Scope of Work:
1. Schematic and PCB Design (EasyEDA or KiCad):
- 16x MFRC522 (mini, pin-header modules), SPI interface (MOSI, MISO, SCK, CS per device), RST per module.
- Tri-state buffering for all MISO lines (SMD buffers, e.g. 74LVC1G125 or similar; OE per CS), clean and short routing.
- Plug-in microcontroller header (STM32/ESP32), all SPI lines and necessary GPIOs routed.
- Power input: USB 5V, onboard 3.3V regulation (efficient switching regulator, e.g. LM3671 preferred over AMS1117).
- Decoupling capacitors (100nF ceramics at each IC/module), well-structured ground and power planes.
- Strict copper keepout (no GND/copper pour or traces) under RFID antenna areas.
- UART/I2C expansion header (with VCC, GND, SCL/SDA/TX/RX; I2C pull-ups if needed).
- Mechanically flat, space-optimized headers and connector layout for tight stacking.
- Mechanical mounting holes and documentation for modular array assembly.
2. Documentation and Files:
- Complete, clearly annotated schematic.
- Professional PCB layout with layer explanations.
- Gerber files, BOM (with LCSC/Mouser/Farnell part numbers preferred).
- Assembly drawings and 3D view/screenshots.
- Brief technical explanation (buffer OE logic, power supply rationale, copper keepout implementation).
- Up to two rounds of minor revisions.
3. Communication:
- Regular status updates.
- Ability to answer technical questions.
- (Optionally) recommendations for layout/part improvements.
Design Priorities & Guidelines:
- Signal integrity: Short, clean SPI lines; no crossings or parallel traces under antenna areas; minimal stub length.
- Power integrity: Wide or polygonal 3.3V/GND rails; star or parallel distribution to all modules; minimal voltage drop under load.
- EMC best practice: Copper keepout (no polygon/traces) under all RFID antennas, thorough decoupling, optimized ground returns.
- Scalability: Ready for multiple arrays in a single system; clear addressing/expansion support.
- Compact stacking: Lowest-possible overall module height for stacked sensor boards.
- Professional appearance: Clean silkscreen, clear labeling, reference designators.
Deliverables:
- Annotated schematic (EasyEDA or KiCad project)
- PCB layout (project files, Gerbers, 3D view)
- Full BOM with suggested sources
- Assembly instructions/silkscreen notes
- Documentation (PDF/README) covering design details and pinout
Your Experience:
PCB design for modular/array sensor systems (RFID or similar a plus)
Strong understanding of signal and power integrity, EMC/EMI design
Familiarity with SPI/I2C/UART, tri-state buffers, and efficient voltage regulators
Experience designing for manufacture and ease of assembly
The project requires best practices in power distribution, EMI/EMC layout, and flat, stackable module integration, suitable for multi-board scalable sensing applications.
Background:
Each PCB module will host 16 MFRC522 (mini, pin-header type, stacked as flat as possible) RFID readers, communicating via SPI with a plug-in microcontroller (STM32 or ESP32 preferred).
The system is designed for up to four such sensor arrays working in parallel, each connecting to a master controller via I2C or UART (addressable per board).
Requirements include robust power supply, professional signal buffering, strict copper keepout under RFID antennas, and clear mechanical design for compact stacking.
Scope of Work:
1. Schematic and PCB Design (EasyEDA or KiCad):
- 16x MFRC522 (mini, pin-header modules), SPI interface (MOSI, MISO, SCK, CS per device), RST per module.
- Tri-state buffering for all MISO lines (SMD buffers, e.g. 74LVC1G125 or similar; OE per CS), clean and short routing.
- Plug-in microcontroller header (STM32/ESP32), all SPI lines and necessary GPIOs routed.
- Power input: USB 5V, onboard 3.3V regulation (efficient switching regulator, e.g. LM3671 preferred over AMS1117).
- Decoupling capacitors (100nF ceramics at each IC/module), well-structured ground and power planes.
- Strict copper keepout (no GND/copper pour or traces) under RFID antenna areas.
- UART/I2C expansion header (with VCC, GND, SCL/SDA/TX/RX; I2C pull-ups if needed).
- Mechanically flat, space-optimized headers and connector layout for tight stacking.
- Mechanical mounting holes and documentation for modular array assembly.
2. Documentation and Files:
- Complete, clearly annotated schematic.
- Professional PCB layout with layer explanations.
- Gerber files, BOM (with LCSC/Mouser/Farnell part numbers preferred).
- Assembly drawings and 3D view/screenshots.
- Brief technical explanation (buffer OE logic, power supply rationale, copper keepout implementation).
- Up to two rounds of minor revisions.
3. Communication:
- Regular status updates.
- Ability to answer technical questions.
- (Optionally) recommendations for layout/part improvements.
Design Priorities & Guidelines:
- Signal integrity: Short, clean SPI lines; no crossings or parallel traces under antenna areas; minimal stub length.
- Power integrity: Wide or polygonal 3.3V/GND rails; star or parallel distribution to all modules; minimal voltage drop under load.
- EMC best practice: Copper keepout (no polygon/traces) under all RFID antennas, thorough decoupling, optimized ground returns.
- Scalability: Ready for multiple arrays in a single system; clear addressing/expansion support.
- Compact stacking: Lowest-possible overall module height for stacked sensor boards.
- Professional appearance: Clean silkscreen, clear labeling, reference designators.
Deliverables:
- Annotated schematic (EasyEDA or KiCad project)
- PCB layout (project files, Gerbers, 3D view)
- Full BOM with suggested sources
- Assembly instructions/silkscreen notes
- Documentation (PDF/README) covering design details and pinout
Your Experience:
PCB design for modular/array sensor systems (RFID or similar a plus)
Strong understanding of signal and power integrity, EMC/EMI design
Familiarity with SPI/I2C/UART, tri-state buffers, and efficient voltage regulators
Experience designing for manufacture and ease of assembly