tags: SLBLabs SLB Labs ZR-7 ZR7 ZR750 Kawasaki KawasakiZR7 TailLight TailLights ATtiny ATtiny85 Arduino C/C++
Hardware • Firmware • Animations • Automotive-grade considerations
The ZR-7 Tail Light is a custom-designed motorcycle tail light built around the ATtiny85 microcontroller.
It spans the complete stack, from schematic and PCB design to low-level firmware and animation logic, with a focus on robustness, simplicity, and visual clarity.
The goal of this project is not only to function as a tail light, but to serve as a well-engineered embedded system suitable for real automotive environments.
- ATtiny85-based control logic
- Addressable RGB LED layout
- Distinct operating modes:
- Tail / running light
- Brake light
- Left / right indicators
- Deterministic, non-blocking firmware
- Designed for 12 V motorcycle electrical systems
- Compact, purpose-built PCB
- MCU: ATtiny85
- LEDs: Addressable RGB LEDs
- Power: 12 V input with on-board regulation
- Inputs: Brake, left indicator, right indicator
Several constraints influenced the hardware design:
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Automotive signal noise Input conditioning and pull-down strategies are used to avoid floating or unstable states.
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Power integrity The circuit is designed to tolerate voltage fluctuations typical of motorcycle electrical systems.
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Mechanical constraints PCB shape, connector placement, and LED layout are optimized for the tail light enclosure.
Schematics, PCB layouts, and manufacturing files are included in the hardware/ directory.
Firmware is written in C, targeting the ATtiny85 directly, with no operating system or dynamic memory usage.
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State-based rendering Tail, brake, and indicator logic are resolved into a single rendering pipeline.
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Time-driven animations All animations are non-blocking and tick-based.
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Config-ready architecture The firmware structure allows future addition of persistent configuration if needed.
Firmware source is located in the firmware/ directory.
The firmware is developed and flashed using the Arduino IDE with an external ISP programmer.
- Arduino IDE
- ATtiny board core (e.g. ATTinyCore by Spence Konde)
- Adafruit_NeoPixel library
- ISP programmer:
- USBtinyISP
- USBasp
- Install the ATtiny board package via the Boards Manager.
- Install the Adafruit_NeoPixel library via the Library Manager.
- Connect the ISP programmer to the ATtiny85 ISP header.
- In the Arduino IDE, configure:
- Board: ATtiny85
- Clock: 16.5 MHz
- B.O.D Level: 4.3v
- Programmer: USBtinyISP or USBasp
Use:
Sketch → Upload Using Programmer
This compiles the firmware and flashes it directly to the ATtiny85.
No bootloader is used.
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- [TODO] Installed tail light images
- [TODO] Short animation demo videos
※ Attached photographs of the assembled PCB are representative of Rev 1.0.
zr7-taillight/
├── firmware/ # ATtiny85 firmware source
├── hardware/ # Schematics and PCB design
├── docs/ # Images and additional documentation
└── README.md
This project is provided as-is, for educational and experimental purposes.
- The author makes no guarantees regarding road legality, safety compliance, or fitness for any particular vehicle.
- Modifying vehicle lighting may be regulated or restricted depending on jurisdiction.
- You are solely responsible for ensuring that any implementation complies with local laws, vehicle regulations, and safety requirements.
Use at your own risk.
This project is sponsored by PCBWay.
PCBWay provided support for PCB manufacturing during the prototyping and validation stages of this project.
It was my first time trying their services and I am pleased with the results.
The order flow was a little different than what I was used to, but I have been diligently followed thorough the whole process.
Other than PCB manufacturing, PCBWay also offers services such as CNC and 3D printing. Be sure to check them out at https://www.pcbway.com/
Released under the MIT License.
See the LICENSE file for details.
The project is functional and actively evolving. Both hardware and firmware are stable, with ongoing refinements and documentation improvements planned.