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Multiflexmeter 3.7.0

Schematics & Design Files

Schematics & Design Files

Section titled “Schematics & Design Files”

Hardware design files and schematics for the Multiflexmeter 3.7.0.

KiCad Project Files

Section titled “KiCad Project Files”

The complete hardware design is available in the hardware/ directory of the repository:

hardware/
├── mfm-v3-smd.kicad_pro     # KiCad project
├── mfm-v3-smd.kicad_sch     # Schematic file
├── mfm-v3-smd.kicad_pcb     # PCB layout
├── fp-lib-table              # Footprint library table
├── sym-lib-table             # Symbol library table
└── lib/                      # Custom libraries

Opening the Design

Section titled “Opening the Design”

Requirements

Section titled “Requirements”
  • KiCad 6.0 or later
  • Internet connection (for downloading standard libraries)

Steps

Section titled “Steps”
  1. Clone the repository
  2. Open hardware/mfm-v3-smd.kicad_pro in KiCad
  3. View schematic: Schematic Editor
  4. View PCB: PCB Editor

Schematic Overview

Section titled “Schematic Overview”

Main Functional Blocks

Section titled “Main Functional Blocks”

  1. Power Supply

    • Input: 3.3V - 5V DC
    • Voltage regulation
    • Power filtering

  2. Microcontroller

    • ATmega1284P-AU (TQFP-44)
    • 16MHz crystal oscillator
    • Reset circuitry
    • ISP programming header

  3. LoRa Radio

    • RFM95W module
    • SPI interface
    • Antenna matching network
    • DIO interrupt connections

  4. Sensor Interface

    • I²C/SMBus pins
    • Pull-up resistors
    • Power control

  5. Programming & Debug

    • ISP header (6-pin)
    • UART header (FTDI-compatible 6-pin)

Manufacturing Files

Section titled “Manufacturing Files”

Gerber Files

Section titled “Gerber Files”

Generate Gerber files from KiCad:

  1. Open PCB Editor
  2. File → Fabrication Outputs → Gerbers
  3. Select output directory
  4. Plot all layers

Required layers:

  • F.Cu, B.Cu (copper)
  • F.Mask, B.Mask (soldermask)
  • F.Silk, B.Silk (silkscreen)
  • Edge.Cuts (board outline)
  • F.Paste, B.Paste (solderpaste)

Drill Files

Section titled “Drill Files”
  1. File → Fabrication Outputs → Drill Files
  2. Generate in same directory as Gerbers

BOM (Bill of Materials)

Section titled “BOM (Bill of Materials)”

Generate BOM:

  1. Open Schematic Editor
  2. Tools → Generate BOM
  3. Use KiBoM plugin or export to CSV

PCB Specifications

Section titled “PCB Specifications”
ParameterValue
Layers2-layer
DimensionsTBD × TBD mm
Thickness1.6mm standard
Copper Weight1 oz (35µm)
Min Track/Space0.15mm / 0.15mm
Min Drill0.3mm
Surface FinishHASL or ENIG

Assembly Notes

Section titled “Assembly Notes”

SMD Components

Section titled “SMD Components”
  • Most components are SMD (0603 or 0805 resistors/capacitors)
  • RFM95W module is through-hole
  • ATmega1284P is TQFP-44 package

Soldering

Section titled “Soldering”
  • Reflow soldering recommended for SMD
  • Hand soldering possible with fine-tip iron
  • Hot air station useful for TQFP

Testing Points

Section titled “Testing Points”
  • Voltage test points for debugging
  • SPI signal test points
  • I²C signal test points

License

Section titled “License”

Hardware design files are released under:

  • License: MIT License (or CERN OHL)
  • Commercial Use: Allowed
  • Modifications: Allowed
  • Attribution: Required

Design Changes

Section titled “Design Changes”

Contributing Hardware Changes

Section titled “Contributing Hardware Changes”
  1. Fork the repository
  2. Make changes in KiCad
  3. Test thoroughly
  4. Submit pull request with:
    • Description of changes
    • Reason for changes
    • Test results
    • Photos (if assembled)

Version History

Section titled “Version History”
VersionChanges
V3.0Initial production version
V3.1(Future) Improvements TBD

Manufacturing Services

Section titled “Manufacturing Services”

Recommended PCB manufacturers:

  • JLCPCB (China, economical)
  • PCBWay (China, good quality)
  • Eurocircuits (Europe, high quality)
  • OSH Park (USA, good for prototypes)

Next Steps

Section titled “Next Steps”