Skip to the content
2 layers58.6 × 18.3 mmBleCaliperV6, the printed circuit board in 3D

This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

Size
58.6 × 18.3 mm
Copper layers
2
Thickness
1.6 mm
Parts
30
Nets
22
Pads
84
Tracks, vias
178, 8
Pours
2
Routed
Yes
KiCad
KiCad 5 (file 20171130)
Created
22 Feb 2026
Updated
22 Feb 2026

Overview

BleCaliperV6 is an open-source printed circuit board by Mechanic-Coder, from the Mechanic-Coder/Wireless-Calipers repository on GitHub. It is a 2-layer board of 58.6 × 18.3 mm with 30 parts on 22 nets, routed with 178 tracks and 8 vias.

It is built around the MCP73831T-2ACI/OT-HXY, MMBT3904 and MMBT5401, with the MMBT5551 among its other parts. Its parts include 13 resistors, 3 diodes, 2 capacitors, 2 transistors and 1 IC.

Main components

4

README

README.md

Wireless Calipers (BleCaliper)

This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper). The goal is to provide hardware and firmware examples that let a digital caliper transmit measurements wirelessly (Bluetooth Low Energy) to a host device. Currently the code reads from Vinca calipers (cheap on Amazon). I believe the same hardware could be used on other brands; the code may just need changes to work with different models.

How does it work?

There are three buttons. Data is transferred to the host device (PC or mobile) via Bluetooth Low Energy (BLE) as keyboard presses.

  • Press Button 1: Send the current measurement as a keyboard input (e.g., "12.34" or "0.567").
  • Press Button 2: Send a "Tab" key to move to the next input field on the host device.
  • Press Button 3: Send an "Shift + Tab" keys to move back in a form.
  • Press Button 2 and Button 3 together: send Delete (backspace).
  • There is also a power switch and built-in charging on the hardware.

Note: Button-to-pin mappings are defined in Code/BleCaliperRev5/BleCaliperRev5.ino (for example: Send = pin 9, Tab = pin 7, Back/Delete = pin 10). Verify the mapping in the source before wiring.

Current Status

  • On-Hold: I have not touched this project since 2022. I may return to it in the future. I'm publishing this as-is for anyone interested in building or improving on it.
  • Repository condition: The repository is unpolished; files from experiments and third-party samples are mixed together, names and folder layout are inconsistent, and some files may be duplicates.
  • The early enclosures were made with FreeCad i then moved to Fusion360 for later versions. I believe the STL's are from the fusion 360 models. I havent looked into shareing the fusion 360 models.

Goal

  • Build and document a small, BLE-capable interface for digital calipers so measurements can be read remotely by a PC or mobile device.
  • Collect prototype hardware (Eagle/PCB files), sketches, and notes in one place so others can reproduce or improve the design.

Credits

Quick Usage / Where to Look

  1. Inspect Resources/ for PCB/Eagle files and their license.txt files.
  2. Search for Arduino/PlatformIO sketches (*.ino, src/) and open them in your preferred IDE. If you do not find .ino files at the top level, look inside subfolders — some sketches may not be tracked or are stored in Resources/.
  3. If you plan to build hardware, follow the included third-party README/license guidance and verify parts and footprints.

Security & Privacy

  • Do not commit Wi?Fi SSIDs, passwords, private keys, API keys, or other credentials. If you discover credentials in tracked files or the Git history, remove them and rotate the affected keys immediately.

License and Redistribution

  • This repository contains mixed content. Some items are original work and some are third-party (Adafruit) with their own licenses. See the included license.txt files in Resources/ for details.

Apology and Cleanup Offer

Apologies for the messy layout — this repo is a personal working archive. If there is interest, I may clean and reorganize the project. Open an issue or comment, and I will prioritize cleanup.

Safety & Liability

This project involves electrical hardware and modifications to measurement tools. Use at your own risk. The repository owner (Mechanic?Coder) and contributors are not responsible for any personal injury, death, loss, or damage to equipment, property, or data that may result from using the hardware, software, or instructions in this repository. Always follow safe working practices, use appropriate protective equipment, and verify designs before powering hardware. If you are unsure, seek assistance from a qualified person.

Parts

30
QtyValueFootprintReferences
8R-10KResistor_SMD:R_0603_1608MetricR1, R4, R5, R7, R8, R9, R10, R11
4SW_DIP_x01Button_Switch_THT:SW_PUSH_6mmBackBtn1, ForwardBtn1, PowerBtn2, SendBtn1
210µFCapacitor_SMD:C_0805_2012MetricC1, C2
2470Resistor_SMD:R_0805_2012MetricR2, R3
2MMBT3904Package_TO_SOT_SMD:SOT-23T1, T2
110K\Resistor_SMD:R_0805_2012MetricR6
1DIODEDiode_SMD:D_SOD-123D1
1GREENLED_SMD:LED_0805_2012MetricLED1
1JSTPHConnector_Wire:SolderWire-0.75sqmm_1x02_P4.8mm_D1.25mm_OD2.3mmbatteryGoesHere1
1MCP73831T-2ACI/OTPackage_TO_SOT_SMD:SOT-23-5U1
1MMBT5401Package_TO_SOT_SMD:SOT-23Q1
1MMBT5551Package_TO_SOT_SMD:SOT-23Q2
1R-1KResistor_SMD:R_0603_1608MetricR12
1R-33Resistor_SMD:R_0603_1608MetricR13
1REDLED_SMD:LED_0805_2012MetricLED3
1Screw_Terminal_01x03Connector_Wire:SolderWire-0.75sqmm_1x03_P4.8mm_D1.25mm_OD2.3mmCaliperWires1
1Screw_Terminal_01x10Connector_PinSocket_2.54mm:PinSocket_1x10_P2.54mm_VerticalItsyBitsy1

More from Mechanic-Coder/Wireless-Calipers

7
  • 2 layersBleCaliperV4, the printed circuit board in 3D

    BleCaliperV4

    Mechanic-Coder/Wireless-Calipers

    This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

    30 parts
  • 2 layers60 × 16.5 mmBleCaliperV8, the printed circuit board in 3D

    BleCaliperV8

    Mechanic-Coder/Wireless-Calipers

    This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

    24 parts
  • 2 layers20.3 × 19 mmAdafruit MicroUSB Lipo, the printed circuit board in 3D

    Adafruit MicroUSB Lipo

    Mechanic-Coder/Wireless-Calipers

    This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

    21 parts
  • 2 layers61.2 × 27.8 mm3btnBoardSurface, the printed circuit board in 3D

    3btnBoardSurface

    Mechanic-Coder/Wireless-Calipers

    This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

    19 parts
  • 2 layers3btnBoard, the printed circuit board in 3D

    3btnBoard

    Mechanic-Coder/Wireless-Calipers

    This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

    16 parts
  • 2 layers3btnBoardSurface, the printed circuit board in 3D

    3btnBoardSurface

    Mechanic-Coder/Wireless-Calipers

    This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

    16 parts
  • 2 layers30.4 × 12.1 mmAdafruit MicroLipo, the printed circuit board in 3D

    Adafruit MicroLipo

    Mechanic-Coder/Wireless-Calipers

    This repository is a working collection of code, PCB/CAD resources, and notes for a Bluetooth-enabled digital caliper project (BleCaliper).

    14 parts

Similar boards

  • 2 layers337 × 150 mmEEZ PSU consolidated r5B13a, the printed circuit board in 3D

    EEZ PSU consolidated r5B13a

    eez-open/psu-hw

    EEZ H24005 programmable bench power supply (powered by Arduino Due)

    546 parts507
  • 4 layers185 × 95 mmEL Load Analog, the printed circuit board in 3D

    EL Load Analog

    fietser28/EL-Load

    The DCL8010 electronic load module features a DC Electronic Load with several modes and protections. This project is the for the development boards for this project. There is a seperate git project for the firmware.

    344 parts15
  • 4 layers180 × 103.5 mmEEZ DIB DCP405plus, the printed circuit board in 3D

    EEZ DIB DCP405plus

    eez-open/dib-dcp405plus

    BB3+ Programmable 1-ch power module

    437 parts12
  • 4 layers146 × 95 mmEEZ DIB MIO168, the printed circuit board in 3D

    EEZ DIB MIO168

    eez-open/dib-mio168

    EEZ DIB Mixed I/O module

    279 parts8
  • 2 layers48 × 55.9 mmBM3451XXDC T28A Board, the printed circuit board in 3D

    BM3451XXDC T28A Board

    YuaXan/BM3451XXDC-T28A-Board

    Rechargeable battery protection board based on BM3451 IC

    84 parts5
  • 2 layers392.6 × 198.3 mmAudio routed, the printed circuit board in 3D

    Audio routed

    Bu3nd14/EDA

    Scripted analog EDA + PCB automation environment (KiCad 10 + ngspice + SKiDL) for macOS Apple Silicon

    657 parts
  • 2 layers88.9 × 89.9 mmLi ion backup, the printed circuit board in 3D

    Li ion backup

    Gosmann/Li-ion-UPS-24V

    24V-input 24V-out lithium ion backup board

    101 parts
  • 2 layers145 × 40 mmAudioAmp, the printed circuit board in 3D

    AudioAmp

    hh-meas/amp

    59 parts

Questions

How big is the BleCaliperV6 PCB?

It measures 58.6 × 18.3 mm and has 2 copper layers, 1.6 mm thick.

What parts does the BleCaliperV6 use?

30 parts, built around the MCP73831T-2ACI/OT-HXY, MMBT3904, MMBT5401 and MMBT5551. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the BleCaliperV6 KiCad files?

From the Mechanic-Coder/Wireless-Calipers repository on GitHub, at the commit this page was made from: the board is Circuit boards/BleCaliperV6/BleCaliperV6.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.

Can I use the BleCaliperV6 design in my own project?

Its repository states no licence, so its author keeps all rights: ask Mechanic-Coder before reusing the design.