Files
Engine-Data-Processing/src/plot.py

102 lines
2.8 KiB
Python

# Copyright (C) 2026 Hector van der Aa <hector@h3cx.dev>
# Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
# SPDX-License-Identifier: GPL-3.0-or-later
import pandas as pd
import matplotlib.pyplot as plt
from pathlib import Path
import argparse
parser = argparse.ArgumentParser()
parser.add_argument("directory", type=Path, help="Source data directory")
args = parser.parse_args()
INPUT_CSV: Path = args.directory
# Width of the artificial pulse, in microseconds.
# Increase this if the pulses are still hard to see.
PULSE_WIDTH_US = 500 # 5 ms
# Optional: plot only a smaller time window.
# Use None to plot the whole recording.
START_US = None
END_US = None
def build_pulse_trace(edge_times_us, pulse_width_us):
"""
Convert falling-edge timestamps into a drawable square pulse trace.
Each edge becomes:
low before edge
high from edge to edge + pulse_width_us
low after that
"""
x = []
y = []
for t in edge_times_us:
x.extend([t, t, t + pulse_width_us, t + pulse_width_us])
y.extend([0, 1, 1, 0])
return x, y
def main():
df = pd.read_csv(INPUT_CSV)
# If the CSV has an index/time column from df_final.to_csv(),
# use the first column as time in microseconds.
time_col = df.columns[0]
# If your CSV columns are: index, crank, cam
time_us = df[time_col]
crank_edges = time_us[df["crank"] == 1].to_numpy()
cam_edges = time_us[df["cam"] == 1].to_numpy()
if START_US is not None:
crank_edges = crank_edges[crank_edges >= START_US]
cam_edges = cam_edges[cam_edges >= START_US]
if END_US is not None:
crank_edges = crank_edges[crank_edges <= END_US]
cam_edges = cam_edges[cam_edges <= END_US]
crank_x, crank_y = build_pulse_trace(crank_edges, PULSE_WIDTH_US)
cam_x, cam_y = build_pulse_trace(cam_edges, PULSE_WIDTH_US)
# Convert microseconds to seconds for a more readable x-axis
crank_x = [x / 1_000_000 for x in crank_x]
cam_x = [x / 1_000_000 for x in cam_x]
# Offset cam vertically so both traces are readable
crank_y = [y * 0.8 + 0 for y in crank_y]
cam_y = [y * 0.8 + 1.2 for y in cam_y]
plt.figure(figsize=(14, 5))
plt.plot(crank_x, crank_y, label="Crank")
plt.plot(cam_x, cam_y, label="Cam")
plt.yticks([0.4, 1.6], ["Crank", "Cam"])
plt.xlabel("Time [s]")
plt.title(f"Crank and Cam Falling Edges, pulse width = {PULSE_WIDTH_US} µs")
plt.grid(True)
plt.legend()
if START_US is not None or END_US is not None:
start_s = START_US / 1_000_000 if START_US is not None else None
end_s = END_US / 1_000_000 if END_US is not None else None
plt.xlim(start_s, end_s)
plt.tight_layout()
plt.show()
if __name__ == "__main__":
main()