2 layers66 × 99.1 mm
2 layers64.4 × 33.7 mm
Predkosciomierz v2 kopia
sebcis123/Bicycle-speedometerBicycle speedometer project based on a Hall effect sensor, featuring an OLED display, low-power design, and custom PCB
- Size
- 64.4 × 33.7 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 25
- Nets
- 32
- Pads
- 91
- Tracks, vias
- 137, 36
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 19 May 2026
- Updated
- 19 May 2026
Overview
Predkosciomierz v2 kopia is an open-source printed circuit board by sebcis123, from the sebcis123/Bicycle-speedometer repository on GitHub. It is a 2-layer board of 64.4 × 33.7 mm with 25 parts on 32 nets, routed with 137 tracks and 36 vias.
It is built around the LM393, BAT54J and IRLML6402, with the MBR0520 among its other parts. Its parts include 7 resistors, 4 capacitors, 3 ICs, 2 diodes and 2 connectors. It belongs with the lEDs and displays and sensors and measurement boards and the STM32 boards of this library.
Main components
4
LM393
SOP-8-16V~16V 0℃~+70℃ 2 2.5mA 250nA 2V~36V 36V 5mV 5nA Fail-safe function Open-drain SOP-8 Comparators ROHSMSKSEMIComparators
BAT54J
SOD-323F1 Independent 200mA 2uA@25V 30V 600mA 800mV@100mA SOD-323F Schottky Diodes ROHSNexperiaSchottky Diodes
IRLML6402
SOT-23-55℃~+150℃ 1 P-Channel 1.3W 110pF 12nC 145pF 20V 3.7A 400mV 633pF 65mΩ@4.5V P-Channel SOT-23 MOSFETs ROHSGuangdong HottechMOSFETs
MBR0520
SOD-123-55℃~+150℃ 20V 450mV@500mA 5.5A 500mA Independent SOD-123 Schottky Diodes ROHSJiangsu Changjing Electronics Technology (CJ)Schottky Diodes
README
README.mdBicycle Speedometer (Prędkościomierz Rowerowy)
A compact, energy-efficient, and low-cost digital bicycle speedometer designed as a complete hardware and software system. The device measures the wheel's rotational speed using a magnetic sensor and displays real-time data on an OLED screen.
Features
- Full System Design: Developed from scratch, including schematics, PCB layout, and simulation.
- Low-Power Optimization: Powered by two standard AAA batteries with a high-efficiency step-up converter.
- Reverse Polarity Protection: Features a low-loss P-MOSFET circuit to protect internal components from incorrect battery insertion.
- Compact Ergonomics: Tailor-made, small-footprint PCB featuring integrated battery clips and accessible programming headers.
Hardware Architecture & Components
The system is split into distinct functional blocks optimized for low current draw:
- Microcontroller: STM32G030F6P6 (ARM Cortex-M0+), chosen for its low cost, efficiency, and rich peripheral set.
- Sensor & Signal Conditioning: DRV5055 linear Hall effect sensor paired with an LM393 comparator. It detects a wheel-mounted magnet and triggers precise external interrupts on the MCU.
- Display: 128x64 OLED screen communicating via the I2C protocol.
- Power Management: LT1615 step-up DC-DC converter, boosting the variable 2x AAA battery voltage (~2.4V - 3V) up to a stable 3.3V rail.
- Protection: IRLML6402 P-channel MOSFET combined with a BAT54J Schottky diode for near-zero voltage drop reverse polarity safety.
PCB Design Specification
The printed circuit board was designed using KiCad.
- Dimensions: 64.5 mm × 34.0 mm (highly compact).
- Trace Widths: 0.3 mm for standard signals, 0.4 mm for power supply traces to mitigate voltage drops.
- Layout Design: The AAA battery holder and SWD programming header are mounted on the bottom side to minimize overall dimensions and simplify enclosure manufacturing.
Parts
25| Qty | Value | Footprint | References |
|---|---|---|---|
| 3 | 10K | Resistor_SMD:R_0805_2012Metric | R3, R5, R6 |
| 2 | 100n | Capacitor_SMD:C_0805_2012Metric | C4, C7 |
| 2 | 10u | Capacitor_SMD:C_0805_2012Metric | C5, C6 |
| 1 | 100K | Resistor_SMD:R_0805_2012Metric | R9 |
| 1 | 1M | Resistor_SMD:R_0805_2012Metric | R7 |
| 1 | 1m | Inductor_SMD:L_1210_3225Metric | L1 |
| 1 | 2 x AA (2.5V - 3V) | Battery:BatteryHolder_Keystone_2468_2xAAA | BT3 |
| 1 | 25K | Resistor_SMD:R_0805_2012Metric | R4 |
| 1 | 4.7u | Inductor_SMD:L_1210_3225Metric | L2 |
| 1 | 604K | Resistor_SMD:R_0805_2012Metric | R8 |
| 1 | BAT54J | Diode_SMD:D_SOD-323F | D3 |
| 1 | Conn_01x03 | Connector_JST:JST_EH_B3B-EH-A_1x03_P2.50mm_Vertical | J3 |
| 1 | Conn_01x05 | Connector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_Vertical | J1 |
| 1 | IRLML6402 | Package_TO_SOT_SMD:SOT-23 | Q1 |
| 1 | LM393 | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U3 |
| 1 | LT1615ES5_TRPBF | LT1615ES5_TRPBF:SOT95P280X145-5N | U1 |
| 1 | MBR0520 | Diode_SMD:D_SOD-123 | D2 |
| 1 | SSD1306 | SSD1306:128x64OLED | Brd1 |
| 1 | STM32G030F6Px | Package_SO:TSSOP-20_4.4x6.5mm_P0.65mm | U2 |
| 1 | SW_Push | Button_Switch_SMD:SW_SPST_TL3342 | SW2 |
| 1 | SW_SPDT | Button_Switch_SMD:SW_SPDT_CK_JS102011SAQN | SW1 |
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Questions
How big is the Predkosciomierz v2 kopia PCB?
It measures 64.4 × 33.7 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Predkosciomierz v2 kopia use?
25 parts, built around the LM393, BAT54J, IRLML6402 and MBR0520. 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 Predkosciomierz v2 kopia KiCad files?
From the sebcis123/Bicycle-speedometer repository on GitHub, at the commit this page was made from: the board is prędkościomierz_pcb/pcb/predkosciomierz_v2_kopia.kicad_pcb and its schematic prędkościomierz_pcb/pcb/predkosciomierz_v2_kopia.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Predkosciomierz v2 kopia design in my own project?
Its repository states no licence, so its author keeps all rights: ask sebcis123 before reusing the design.