embedded-etrace 0.1.5

Decode and visualise no_std embedded execution traces over RTT or any byte transport

embedded-etrace

Decode and visualize embedded execution traces over RTT or any byte transport.

The companion Rust crate (execution_trace) provided by the Cargo package execution-trace runs on your firmware and emits length-delimited protobuf frames for task activations, ISR entries, and point-in-time markers. This Python package decodes those frames on the host and produces interactive HTML timing diagrams.

Example of a time trace diagram

Installation

# Core decoder only (no diagram dependencies):
pip install embedded-etrace

# With the interactive Bokeh diagram generator:
pip install embedded-etrace[diagram]

Requires Python 3.11+.

Quick start

1. Custom transport — decode a live stream

Implement a loop that appends raw bytes from your transport (RTT, UART, TCP…) into a bytearray and call decode_tracing_stream each iteration:

from execution_trace import (
    SequenceTracker, TraceEventBuffer, decode_tracing_stream, write_tracing_csv,
)

buf = bytearray()
tracker = SequenceTracker("my-device")
event_buffer = TraceEventBuffer()

while True:
    buf += transport.read()                         # append whatever arrived
    decode_tracing_stream(buf, tracker, event_buffer)

# When the session ends:
event_buffer.flush_pending()                        # warn about open spans
csv_path = write_tracing_csv(
    event_buffer.records + event_buffer.markers,    # type: ignore[operator]
    output_dir="data",
)
print(f"Trace written → {csv_path}")

decode_tracing_stream consumes complete frames from buf in-place and handles device resets transparently (the sequence number jumps backward on firmware reboot).

2. Decode a recorded binary file

Use the etrace-decode console script:

etrace-decode recording.bin
etrace-decode recording.bin --output ./data

This produces a timestamped trace_YYYYMMDD_HHMMSS.csv and updates the trace_latest.csv symlink.

3. Generate a timing diagram

etrace-diagram                          # reads trace_latest.csv, writes diagram.html
etrace-diagram data/trace_latest.csv --output out/diagram.html --title "Flight run #7"

Or call the API directly:

from pathlib import Path
from execution_trace.diagram import generate_diagram

result = generate_diagram(
    csv_path=Path("trace_latest.csv"),
    output_path=Path("diagram.html"),
    title="Flight run #7",
)
print(f"{result.n_events} events, {result.n_lanes} lanes, {result.n_missed} deadline misses")

CSV format

Column	Type	Description
name	string	Span or marker name
type	string	task, isr, or marker
start_us	float	Activation timestamp in µs
end_us	float	Completion timestamp in µs (= start_us for markers)
priority	int	Scheduler priority (0 if unknown)
deadline_us	float	Absolute deadline in µs (optional)
value	int	Optional u32 marker payload

Wire format

Each frame is a standard protobuf length-delimited record:

[ varint: payload_length ][ proto bytes: TraceEvent ]

The protobuf schema lives in :file:execution-trace/proto/tracing.proto (sibling Rust crate in the same repository).

Development

# Editable install with all dev dependencies:
pip install -e ".[diagram,dev]"

# Run the test suite:
pytest tests/ -v

# Type-check:
mypy src/execution_trace