# Kayak Impact Sensor a953 ## Description Compact kayak and canoe impact sensor PCB with USB-C Li-ion charging, ATmega328P-AU control, ADXL345 breakout sensing, 3.3V regulated power, OLED and ISP headers, and corner mounting holes. ## Project Details - **Owner:** mattia46 - **Created:** 4/1/2026 - **Last Updated:** 4/1/2026 - **Visibility:** Public - **System Architecture:** ```mermaid flowchart TD USB["USB-C 5V Input"] --> ESD["VBUS ESD Protection"] ESD --> CHG["TP4056 Charger Module"] CHG --> BAT["Battery Pads J1"] BAT --> SW["Power Switch SW1"] SW --> LDO["MCP1703 3.3V LDO"] LDO --> MCU["ATmega328P-AU 8MHz Internal"] LDO --> ACC["ADXL345 Breakout Module"] MCU <-->|"I2C SDA SCL"| ACC MCU --> OLED["J2 OLED Header"] MCU --> ISP["J3 ISP Header"] MCU --> LED["Status LED on PD7"] MCU --> BTN["External Button SW2 to GND"] ``` - **Copies:** 1 ## Key Components ### D1 — [ESD5Z5.0T1G](https://www.flux.ai/adrian95/esd5z5p0t1g.md) - Role Details: Clamps surges on USB-C VBUS near connector entry - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Diode - Role: ESD Protection - Manufacturer Part Number: ESD5Z5.0T1G - LCSC Part Number: C5199798 - Manufacturer Name: onsemi - Package: SOD-523 - Datasheet URL: https://www.onsemi.com/pdf/datasheet/esd5z2.5t1-d.pdf **Pins:** - A [pin 2] - K [pin 1] ### D2 — [LTST-C170KGKT](https://www.flux.ai/jecstronic/ltst-c170kgkt.md) - Forward Voltage: 2V - Datasheet URL: https://optoelectronics.liteon.com/upload/download/DS22-2000-073/LTST-C170KGKT.pdf - LCSC Part Number: C72043 - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: LED - Role: Status LED - Manufacturer Part Number: LTST-C170KGKT - Role Details: Indicator LED driven from PD7 through 330R resistor - Package: 0805 - Manufacturer Name: Lite-On Inc. **Pins:** - A [pin 2] - K [pin 1] ### D3 — [BZ-C0805-P2-E1](https://www.flux.ai/lcsc/bz-c0805-p2-e1.md) - LCSC Part Number: C2833069 - Package or Case Code: LED0805-RD_RED - Manufacturer Part Number: BZ-C0805-P2-E1 - Role: Charge Status LED - Part Type: Light Emitting Diodes (LED) - Package: 0805 - Manufacturer Name: baizou(百洲) - JLCPCB Part Class: Extended Part - Role Details: Red LED indicates active charging from TP4056 status output **Pins:** - A [pin 2] - K [pin 1] ### D4 — [LTST-C170KGKT](https://www.flux.ai/jecstronic/ltst-c170kgkt.md) - Manufacturer Part Number: LTST-C170KGKT - Manufacturer Name: Lite-On Inc. - Role: Charge Complete LED - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: Green LED indicates charge complete from TP4056 status output - Package: 0805 - Part Type: LED - Datasheet URL: https://optoelectronics.liteon.com/upload/download/DS22-2000-073/LTST-C170KGKT.pdf - LCSC Part Number: C72043 - Forward Voltage: 2V **Pins:** - A [pin 2] - K [pin 1] ### J1 — [BATTERY](https://www.flux.ai/adrian95/battery.md) - Part Type: Connector - Package: 2-pad battery connector - Role: Battery Pads - Role Details: Board-edge battery positive and negative pads on upper short side **Pins:** - P1 - P2 ### J2 — [61300411121](https://www.flux.ai/adrian95/61300411121.md) - License: https://creativecommons.org/licenses/by/4.0/ - Role: OLED Header - Datasheet URL: https://www.we-online.com/components/products/datasheet/61300411121.pdf - Package: 1x4 2.54mm THT - Role Details: 1x4 header for OLED connection carrying GND, 3V3, SDA, SCL - Manufacturer Part Number: 61300411121 - Package or Case Code: HDRV4W95P0X254_1X4_1016X254X854P - Manufacturer Name: Wurth Elektronik - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] ### J3 — [61300621121](https://www.flux.ai/adrian95/61300621121.md) - Role: ISP Header - Part Type: Connector - Datasheet URL: https://www.we-online.com/katalog/datasheet/6130xx21121.pdf - Role Details: AVR ISP programming header for MOSI, MISO, SCK, RESET, VCC, GND - Manufacturer Part Number: 61300621121 - License: https://creativecommons.org/licenses/by/4.0/ - Package or Case Code: HDRV6W64P254_2X3_762X508X889P - Package: 2x3 2.54mm THT - Manufacturer Name: Wurth Elektronik **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] ### J4 — [UJ20-C-V-G-SMT-P16-TR-65](https://www.flux.ai/adrian95/uj20-c-v-g-smt-p16-tr-65.md) - Manufacturer Part Number: UJ20-C-V-G-SMT-P16-TR-65 - Part Type: USB C - Package or Case Code: UJ20CVGSMTP16TR65 - Datasheet URL: https://www.cuidevices.com/product/resource/digikeypdf/uj20-c-v-g-smt-p16-tr-65.pdf - Role: USB-C Power Input - Package: USB-C 16-pin SMT - LCSC Part Number: C2765186 - Role Details: Provides VBUS and GND for TP4056 charger input, CC pins strapped for sink mode - Manufacturer Name: Same Sky - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - CC1 [pin A5] - CC2 [pin B5] - DN1 [pin A7] - DN2 [pin B7] - DP1 [pin A6] - DP2 [pin B6] - DUMMY_1 [pin 1] - DUMMY_2 [pin 2] - DUMMY_3 [pin 3] - DUMMY_4 [pin 4] - GND_1 [pin A1] - GND_2 [pin A12] - GND_3 [pin B1] - GND_4 [pin B12] - SBU1 [pin A8] - SBU2 [pin B8] - VBUS_1 [pin A4] - VBUS_2 [pin A9] - VBUS_3 [pin B4] - VBUS_4 [pin B9] ### SW1 — [TB003-500-P02BE](https://www.flux.ai/adrian95/tb003-500-p02be.md) - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: VBAT_SW GND external power switch wire pads, 5mm pitch, target hole 1.2mm - Role: External Switch Pads - Manufacturer Part Number: TB003-500-P02BE - Package: 2-pin 5.00mm THT - Datasheet URL: https://www.cuidevices.com/product/resource/tb003-500.pdf - Manufacturer Name: CUI Devices - Part Type: Connector **Pins:** - 1 [pin 1] - 2 [pin 2] ### SW2 — [TB003-500-P02BE](https://www.flux.ai/adrian95/tb003-500-p02be.md) - Manufacturer Name: CUI Devices - Datasheet URL: https://www.cuidevices.com/product/resource/tb003-500.pdf - Part Type: Connector - Package: 2-pin 5.00mm THT - Role Details: PD2 GND external button wire pads, 5mm pitch, target hole 1.0mm - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: TB003-500-P02BE - Role: External Button Pads **Pins:** - 1 [pin 1] - 2 [pin 2] ### U1 — [ATMEGA328P-AU](https://www.flux.ai/jecstronic/atmega328p-au.md) - Datasheet URL: https://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: ATMEGA328P-AU - Role: Main MCU - Role Details: ATmega328P-AU, internal 8MHz, handles ADXL345 I2C, OLED header, ISP programming, button input, LED output - Manufacturer Name: Microchip Technology Inc. - Part Type: Integrated Circuit - Package: TQFP-32 **Pins:** - (PCINT0/CLKO/ICP1)_PB0 [pin 12] - (PCINT1/OC1A)_PB1 [pin 13] - (PCINT19/OC2B/INT1)_PD3 [pin 1] - (PCINT2/SS/OC1B)_PB2 [pin 14] - (PCINT20/XCK/T0)_PD4 [pin 2] - (PCINT21/OC0B/T1)_PD5 [pin 9] - (PCINT22/OC0A/AIN0)_PD6 [pin 10] - (PCINT23/AIN1)_PD7 [pin 11] - (PCINT3/OC2A/MOSI)_PB3 [pin 15] - (PCINT4/MISO)_PB4 [pin 16] - (PCINT6/XTAL1/TOSC1)_PB6 [pin 7] - (PCINT7/XTAL2/TOSC2)_PB7 [pin 8] - ADC6 [pin 19] - ADC7 [pin 22] - AREF [pin 20] - AVCC [pin 18] - GND_1 [pin 3] - GND_2 [pin 5] - GND_3 [pin 21] - PB5_(SCK/PCINT5) [pin 17] - PC0_(ADC0/PCINT8) [pin 23] - PC1_(ADC1/PCINT9) [pin 24] - PC2_(ADC2/PCINT10) [pin 25] - PC3_(ADC3/PCINT11) [pin 26] - PC4_(ADC4/SDA/PCINT12) [pin 27] - PC5_(ADC5/SCL/PCINT13) [pin 28] - PC6_(~RESET~/PCINT14) [pin 29] - PD0_(RXD/PCINT16) [pin 30] - PD1_(TXD/PCINT17) [pin 31] - PD2_(INT0/PCINT18) [pin 32] - VCC_1 [pin 4] - VCC_2 [pin 6] ### U2 — [MCP1703T-3302E/CB](https://www.flux.ai/adrian95/mcp1703t-3302ecb.md) - Manufacturer Part Number: MCP1703T-3302E/CB - Symbol Style: Legacy - Role: LDO Regulator - Role Details: Generates regulated 3.3V rail for MCU and ADXL345 breakout from switched battery node - Datasheet URL: http://ww1.microchip.com/downloads/en/DeviceDoc/22049f.pdf - License: https://creativecommons.org/licenses/by/4.0/ - LCSC Part Number: C70078 - Package: SOT-23A-3 - Manufacturer Name: Microchip Technology - Part Type: Linear Regulator **Pins:** - GND [pin 1] - VIN [pin 3] - VOUT [pin 2] ### U3 — [TP4056](https://www.flux.ai/lcsc/tp4056.md) - Role: Battery Charger - Role Details: Linear Li-ion charger from USB-C 5V input to battery pads, with EN and STAT outputs unused - LCSC Part Number: C725790 - Package or Case Code: ESOP-8_L4.9-W3.9-P1.27-LS6.0-BL-EP - Part Type: Battery Management ICs - Package: ESOP-8 - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2409241408_UMW-Youtai-Semiconductor-Co---Ltd--TP4056_C725790.pdf - Product Info Url: https://lcsc.com/product-detail/PMIC-Battery-Management_UMW-Youtai-Semiconductor-Co-Ltd-TP4056_C725790.html - Manufacturer Part Number: TP4056 - JLCPCB Part Class: Extended Part - Manufacturer Name: UMW(友台半导体) **Pins:** - ~{CHRG} [pin 7] - ~{STDBY} [pin 6] - BAT [pin 5] - CE [pin 8] - EP [pin 9] - GND [pin 3] - PROG [pin 2] - TEMP [pin 1] - VCC [pin 4] ### U4 — [ADXL345](https://www.flux.ai/adrian95/adxl345.md) - License: https://creativecommons.org/licenses/by/4.0/ - Role: Accelerometer Module - Role Details: ADXL345 breakout/evaluation module used as PCB-mounted module for impact sensing - Manufacturer Name: Adafruit Industries LLC - Manufacturer Part Number: 1231 - Datasheet URL: https://cdn-learn.adafruit.com/downloads/pdf/adxl345-digital-accelerometer.pdf - Package: Breakout Module - Part Type: Development Board **Pins:** - 1 [pin 1] - 10 [pin 10] - 11 [pin 11] - 12 [pin 12] - 13 [pin 13] - 14 [pin 14] - 2 [pin 2] - 3 [pin 3] - 4 [pin 4] - 5 [pin 5] - 6 [pin 6] - 7 [pin 7] - 8 [pin 8] - 9 [pin 9] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/mattia46/kayak-impact-sensor-a953](https://www.flux.ai/mattia46/kayak-impact-sensor-a953).* --- *Generated from [https://www.flux.ai/mattia46/kayak-impact-sensor-a953](https://www.flux.ai/mattia46/kayak-impact-sensor-a953)*