Serial Bridge

Python serial bridge connecting Arduino devices to KUKSA Databroker and Pullpiri.

Overview

This bridge reads input from Arduino devices and:

1. Sends the joystick button state to KUKSA Databroker and drives the LED Arduino (GREEN on press, OFF on release)
2. Sends YAML artifacts to Pullpiri based on the gear (rotary encoder) button input

Build

Built via docker compose from the serial-bridge directory (image serial-bridge:latest):

cd ..
docker compose build

Environment Variables

Variable	Default	Description
DATABROKER_IP	resiso-databroker	KUKSA Databroker hostname/IP
DATABROKER_PORT	55555	KUKSA Databroker port
MASTER_IP	host.docker.internal	Master's Pullpiri apiserver IP. The orchestrator passes MASTER_NODE_IP; falls back to the docker host gateway when unset
NODE_NAME	(none, required)	Guest Pullpiri node name. Replaces the ${NODE_NAME} placeholder in the YAMLs under pullpiri-yaml/ before they are sent. The orchestrator passes GUEST_NODE_NAME

Serial Ports

Port	Device	Direction
/dev/arduino_joystick	Joystick button	Input
/dev/arduino_led	NeoPixel LED	Output
/dev/arduino_gear	Rotary encoder button	Input

Data Flow

Joystick → KUKSA + LED

1. Button press detected → Queue message True
2. Thread-DB sends to DataBroker: Vehicle.Cabin.ResourceIsolation.ButtonPressed=True
3. Main thread sends GREEN\n to LED Arduino
4. Button release → Same flow with False and OFF\n

Gear → Pullpiri

The gear Arduino sends a single digit over serial when its button is pressed. The Thread-Gear worker maps it to a workload YAML and posts it to Pullpiri. A repeated value for the current mode is ignored.

Gear input	Action	YAML sent
1	Launch the LED workloads (timpani + normal controllers)	/yaml/container-launch.yaml
0	Stop the LED workloads	/yaml/container-stop.yaml

The launch manifest starts two LED controllers: led-timpani-controller (a TIMPANI-scheduled real-time task) and led-normal-controller (a plain task). Under CPU stress the timpani LED keeps a steady blink period while the normal LED degrades — this is the resource-isolation effect the demo shows.

YAML Artifacts

Located in /yaml/ directory (mounted volume):

• container-launch.yaml - Sent when gear input is 1 (HIGH LOAD / LAUNCH)
• container-stop.yaml - Sent when gear input is 0 (LOW LOAD / STOP)