Ros2Bnyahaj

ROS2Bnyahaj Communication Overview

ROS2Bnyahaj handles communication between the Firmware stack (Teensy) and the Software stack (ROS) over a UART channel.

This is the primary pathway for transmitting critical system information, including:

• Steering commands
• Buggy position data
• Sensor telemetry
• Debug information

Because this node is mission-critical, it is configured in ROS to automatically restart if it crashes. Repeated restarts may indicate a deeper system bug.

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Key Software Components

Host Communication Library

host_comm.py

Handles low-level serial packet encoding/decoding and UART communication.

ROS Serial Node

ros_to_bnyahaj.py

ROS node responsible for reading serial data and publishing relevant ROS topics.

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Packet Definitions

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NAND Teensy → NAND ROS (Rosbag)

NAND Debug Packet

Field	Type	Description
TX12 (controller) connected	bool	Whether the TX12 controller is connected
Operator ready	bool	Operator enable/ready state
RC steering angle	float	Steering angle from RC
Stepper steering angle	float	Steering angle reported by stepper
Stepper alarm	bool	Stepper fault state
Brake status	bool	Brake engaged/disengaged
Use auton steer	bool	Whether autonomous steering is active
RC Uplink quality	int	RC signal quality metric
Encoder angle	float	Raw encoder angle
Accelerometer	float	Acceleration reading
RFM69 missed packet	bool	Whether a radio packet was missed
Teensy timestamp	int	millis() timestamp from Teensy

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NAND UKF Packet

Field	Type	Description
Eastern	float	Position (meters, UTM Easting)
Northern	float	Position (meters, UTM Northing)
θ (theta)	float	Heading (radians)
ω (omega)	float	Angular velocity (rad/s)
Velocity	float	Linear velocity (m/s)
Teensy timestamp	int	millis() timestamp from Teensy

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NAND Raw GPS Packet

Field	Type	Description
Sequence number	int	GPS packet sequence ID
Eastern (unfiltered)	float	UTM Easting (meters)
Northern (unfiltered)	float	UTM Northing (meters)
Fix type	int	GPS fix classification
Accuracy	float	GPS reported accuracy
GPS time	float	Timestamp from GPS module
Teensy timestamp	int	millis() timestamp from Teensy

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NAND Teensy → SC Teensy (via RFM69)

(Also logged in SC Rosbag via SC Teensy)

NAND POS Packet

Field	Type	Description
NAND GPS Sequence Number	int	Sequence ID from NAND GPS
NAND GPS Fix	int	Fix classification
X / East (unfiltered)	float	UTM Easting (meters)
Y / North (unfiltered)	float	UTM Northing (meters)

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SC Teensy → SC ROS (Rosbag)

SC Debug Packet

Field	Type	Description
TX12 state	bool	Controller connection state
Operator ready	bool	Operator enable/ready state
RC steering angle	float	Steering angle from RC
Stepper steering angle	float	Steering angle reported by stepper
Stepper alarm	bool	Stepper fault state
Brake status	bool	Brake state
Use auton steer	bool	Whether autonomous steering is active
RC Uplink quality	int	RC signal quality
Raw encoder	float	Raw encoder reading
Missed packet count	int	Packets missed since last debug packet
Teensy timestamp	int	millis() timestamp from Teensy

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SC Sensors Packet

Field	Type	Description
Steering	float	Actual stepper steering angle
Speed	float	Encoder-derived speed (m/s)
Teensy timestamp	int	millis() timestamp from Teensy

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Timestamp Roundtrip

Used for synchronization and latency measurement.

Field	Type	Description
Teensy timestamp	int	millis() from firmware
Absolute timestamp	float	Software-side absolute time