MCU1 LED Control ECU (Arduino Uno + MCP2515)

This device drives an 8-LED strip over CAN and reports its current light status back to the Raspberry Pi 5 running the Kuksa CAN Provider.

Hardware

Component	Details
Board	Arduino Uno R4 WiFi
CAN transceiver	MCP2515 module (8 MHz crystal, TJA1050)
LED output	WS2812 LED strip (8 LEDs)
Bus	CAN at 500 kbit/s

See the Hardware BOM for sourcing details and wiring instructions.

Responsibilities

• Receive BlinkerCommand CAN frames from the Raspberry Pi 5
• Drive the WS2812 LED strip to show turn-indicator and brake-light states
• Send BlinkerStatus CAN frames reporting the current state back to the Pi

Arduino Libraries

• FastLED — WS2812 LED control
• 107-Arduino-MCP2515 — MCP2515 CAN controller driver

LED Allocation

LEDs (1-based)	LEDs (0-based)	Function
1-2	0-1	Left indicator
4-5	3-4	Brake light
7-8	6-7	Right indicator

CAN Protocol

Payload Encoding

The Arduino expects a single-byte payload where each bit (or bit pair) represents a VSS signal. The same encoding is used when publishing status back to the Raspberry Pi.

Bit(s)	VSS Signal
0	Vehicle.Body.Lights.DirectionIndicator.Left.IsSignaling
1	Vehicle.Body.Lights.DirectionIndicator.Right.IsSignaling
2-3	Vehicle.Body.Lights.Brake.IsActive (0=INACTIVE, 1=ACTIVE, 2=ADAPTIVE)

CAN IDs

CAN ID	Name	Direction	Description
0x120 (288)	BlinkerCommand	Raspberry Pi → Arduino	Set blinker and brake state
0x121 (289)	BlinkerStatus	Arduino → Raspberry Pi	Report current state

See VSS / CAN Signal Mapping for the full DBC definition and value transforms.

LED Blinking Behavior

Signal State	LED Behavior
Left indicator ON	LEDs 0-1 blink at 1 Hz (500 ms on/off)
Right indicator ON	LEDs 6-7 blink at 1 Hz (500 ms on/off)
Brake ACTIVE	LEDs 3-4 solid on
All OFF	All LEDs off

Wiring

MCP2515 to Arduino

MCP2515 Pin	Arduino Pin
VCC	5 V
GND	GND
CS	D10 (SPI SS)
SO	D12 (SPI MISO)
SI	D11 (SPI MOSI)
SCK	D13 (SPI SCK)
INT	D2

The WS2812 LED strip data line connects to a digital output pin (see sketch for the exact pin).

CAN Bus Connection

Connect CAN_H and CAN_L between the MCP2515 module and the Waveshare RS485 CAN Hat on the Raspberry Pi 5. Use twisted-pair wiring and add 120 Ω termination resistors at each end of the bus.

Configuration

• CAN bitrate: 500 kbit/s
• MCP2515 clock: 8 MHz

No Wi-Fi or MQTT configuration is needed — this ECU communicates solely over CAN.

Sketch Location

devices/mcu1-led-control-can/mcu1-led-control-can/mcu1-led-control-can.ino

Upload via the Arduino IDE (2.x) with the Arduino UNO R4 WiFi board selected.