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import numpy as np
def process_rs485_signal(input_csv,
output_csv,
edge_threshold,
low_threshold,
high_threshold,
window_size=6,
samples_to_average=10,
refractory_samples=15):
"""
Processes an analog RS485 capture CSV to detect signal edges and assign levels.
Parameters:
input_csv (str): Path to the input CSV file. The CSV should have at least two columns: 'time' and 'voltage'.
output_csv (str): Path to the output CSV file that will contain the detected edges.
edge_threshold (float): Minimum voltage change (over the past window_size samples) required to detect an edge.
low_threshold (float): Upper bound for the averaged voltage to be considered "low".
high_threshold (float): Lower bound for the averaged voltage to be considered "high".
window_size (int): Number of previous samples to compare against for detecting a change (default: 5).
samples_to_average (int): Number of samples to average after an edge is detected to determine the new level (default: 20).
refractory_samples (int): Number of samples to skip after detecting an edge to avoid multiple triggers (default: 20).
The function writes a CSV with two columns: 'time' (the time at which the edge was detected)
and 'level' (the new state: "low", "high", or "floating").
"""
# Load the CSV into a DataFrame.
data = pd.read_csv(input_csv)
# Ensure that the required columns are present.
if not {"time", "voltage"}.issubset(data.columns):
raise ValueError("Input CSV must contain 'time' and 'voltage' columns.")
times = data['time'].values
voltages = data['voltage'].values
N = len(voltages)
edges = [] # List to store detected edges as [time, level]
i = window_size # Start after the initial window
# Loop until we have enough remaining samples for the averaging window.
while i < N - samples_to_average:
# Compare the current voltage with the voltage from 'window_size' samples ago.
voltage_change = voltages[i] - voltages[i - window_size]
if abs(voltage_change) >= edge_threshold:
# Average the next 'samples_to_average' samples to determine the new level.
avg_voltage = np.mean(voltages[i:i + samples_to_average])
if avg_voltage < low_threshold:
level = "low"
elif avg_voltage > high_threshold:
level = "high"
else:
level = "floating"
# Record the time of the detected edge and its new level.
edges.append([times[i], level])
# Skip ahead by a refractory period to avoid multiple detections of the same edge.
i += refractory_samples
else:
i += 1
# Convert the list of edges to a DataFrame and write it to CSV.
edges_df = pd.DataFrame(edges, columns=['time', 'level'])
edges_df.to_csv(output_csv, index=False)
def decode_rs485_packets(edges_csv, packet_gap_threshold, bit_interval):
"""
Decodes RS485 packets from an edges CSV file into a list of (tx_data, rx_data) pairs.
Parameters:
edges_csv (str): Path to the CSV file containing edges. The CSV should have two columns:
'time' (timestamps) and 'level' (string: "low", "high", or "floating").
packet_gap_threshold (float): Time gap (in the same units as 'time') that indicates a new packet.
bit_interval (float): Expected time duration of one bit period.
Returns:
List[Tuple[str, str]]: A list of tuples where each tuple is (tx_data, rx_data).
Each is a binary string representing the data from that transfer.
Assumptions:
- The CSV rows are in chronological order.
- Each packet consists of two transfers:
* TX transfer: starts with a start bit (first edge) and then the TX data bits.
* RX transfer: starts after a floating level is detected; its first edge is a start bit (and not a data bit).
- Signal levels are interpreted as: "low" -> '0' and "high" -> '1'.
- Edges occur on bit boundaries, but if the time between consecutive edges is greater than one bit_interval,
we assume that the previous bit was held for the missing bit periods.
"""
# Read the CSV file into a DataFrame.
df = pd.read_csv(edges_csv)
if not {"time", "level"}.issubset(df.columns):
raise ValueError("CSV must contain 'time' and 'level' columns.")
# Create a list of (time, level) tuples.
edges = list(zip(df['time'], df['level']))
# Partition the entire stream into packets based on a time gap threshold.
packets = []
current_packet = [edges[0]]
for i in range(1, len(edges)):
current_edge = edges[i]
prev_edge = edges[i - 1]
if (current_edge[0] - prev_edge[0]) > packet_gap_threshold:
# A large time gap indicates a new packet.
packets.append(current_packet)
current_packet = [current_edge]
else:
current_packet.append(current_edge)
if current_packet:
packets.append(current_packet)
def decode_segment(segment_edges, bit_interval):
"""
Decodes a transfer segment (list of (time, level)) into a binary string.
The first edge is assumed to be a start bit and is skipped.
Uses timing differences to determine if a bit is held for multiple bit periods.
Parameters:
segment_edges (List[Tuple[float, str]]): Edges for one transfer (either TX or RX).
bit_interval (float): The expected duration of one bit period.
Returns:
A binary string (e.g., "101010") representing the data bits.
Returns an empty string if there are insufficient edges to decode.
"""
if len(segment_edges) < 2:
# Not enough edges to have a start bit and at least one data bit.
return ""
bits = []
# Start with the second edge (first edge after the start bit).
prev_time, prev_level = segment_edges[1]
if prev_level.lower() == "floating":
# If the first data edge is floating, we cannot decode a valid bit.
return ""
prev_bit = "0" if prev_level.lower() == "low" else "1"
bits.append(prev_bit)
last_time = prev_time
# Process remaining edges.
for (t, level) in segment_edges[2:]:
# Skip any floating edges that might appear within the transfer.
if level.lower() == "floating":
continue
dt = t - last_time
# Determine how many bit periods have passed.
# We use rounding to account for slight drift.
n_intervals = max(1, int(round(dt / bit_interval)))
# If more than one bit period elapsed, assume the previous bit was held.
if n_intervals > 1:
bits.extend([prev_bit] * (n_intervals - 1))
# Append the new bit.
current_bit = "0" if level.lower() == "low" else "1"
bits.append(current_bit)
last_time = t
prev_bit = current_bit
return "".join(bits)
packets_data = [] # List to hold the decoded (tx_data, rx_data) pairs.
# Process each packet.
for packet in packets:
# Look for the first occurrence of a floating edge.
# This edge marks the boundary between TX and RX.
floating_index = None
for i, (t, level) in enumerate(packet):
if level.lower() == "floating":
floating_index = i
break
if floating_index is None:
# No floating edge found in this packet; skip or handle as needed.
continue
# The TX segment is assumed to be all edges before the floating transition.
tx_edges = packet[:floating_index]
# The RX segment starts after the floating edge.
rx_edges = packet[floating_index + 1:]
# Decode each segment.
tx_data = decode_segment(tx_edges, bit_interval)
rx_data = decode_segment(rx_edges, bit_interval)
packets_data.append((tx_data, rx_data))
return packets_data
import pandas as pd
import matplotlib.pyplot as plt
import numpy as np
def visualize_single_packet(analog_csv, edges_csv, decoded_packets, packet_index, packet_gap_threshold):
"""
Visualizes a single packet by plotting the analog waveform (with edge markers)
and displaying the decoded binary TX/RX data for that packet.
Parameters:
analog_csv (str): Path to the analog capture CSV file. Should contain "time" and "voltage" columns.
edges_csv (str): Path to the edges CSV file. Should contain "time" and "level" columns.
decoded_packets (List[Tuple[str, str]]): A list of (tx_data, rx_data) tuples, one per packet.
packet_index (int): Index (0-indexed) of the packet to visualize.
packet_gap_threshold (float): Time gap (in same units as 'time') that indicates a new packet.
The function partitions the edges into packets, selects the specified packet, determines the
time window covering that packet (with a margin), and plots:
- The analog waveform (restricted to that window)
- Vertical dashed lines at each edge (color-coded by level)
- A text box below showing the TX and RX binary strings for that packet.
"""
# Load the analog signal.
analog_df = pd.read_csv(analog_csv)
time_data = analog_df['time'].values
voltage = analog_df['voltage'].values
# Load the edges.
edges_df = pd.read_csv(edges_csv)
edges = list(zip(edges_df['time'].values, edges_df['level'].values))
# Partition the edges into packets.
packets = []
current_packet = [edges[0]]
for i in range(1, len(edges)):
# If the gap is larger than the threshold, start a new packet.
if (edges[i][0] - edges[i-1][0]) > packet_gap_threshold:
packets.append(current_packet)
current_packet = [edges[i]]
else:
current_packet.append(edges[i])
if current_packet:
packets.append(current_packet)
# Check if packet_index is valid.
if packet_index < 0 or packet_index >= len(packets):
raise ValueError(f"Packet index {packet_index} is out of range. There are only {len(packets)} packets.")
# Select the packet.
packet_edges = packets[packet_index]
# Determine time window for this packet.
packet_start = packet_edges[0][0]
packet_end = packet_edges[-1][0]
# Use 5% of the packet duration as margin on each side (or a minimum margin if duration is 0)
margin = max((packet_end - packet_start) * 0.05, 0.000001)
window_start = packet_start - margin
window_end = packet_end + margin
# Filter analog data to this time window.
window_mask = (time_data >= window_start) & (time_data <= window_end)
time_window = time_data[window_mask]
voltage_window = voltage[window_mask]
# Get the decoded data for this packet.
tx_data, rx_data = decoded_packets[packet_index] if packet_index < len(decoded_packets) else ("", "")
# Create the figure with two subplots.
fig, (ax_waveform, ax_text) = plt.subplots(2, 1, figsize=(14, 8),
gridspec_kw={'height_ratios': [3, 1]},
sharex=True)
# Plot the analog waveform.
ax_waveform.plot(time_window, voltage_window, label="Analog Signal", color='black')
ax_waveform.set_ylabel("Voltage")
ax_waveform.set_title(f"Analog Signal & Edges for Packet {packet_index + 1}")
# Overlay edge markers for this packet.
for t, level in packet_edges:
if level.lower() == "low":
col = 'blue'
elif level.lower() == "high":
col = 'red'
elif level.lower() == "floating":
col = 'green'
else:
col = 'gray'
ax_waveform.axvline(x=t, color=col, linestyle="--", alpha=0.7)
ax_waveform.text(t, np.max(voltage_window), level, rotation=90,
verticalalignment='bottom', fontsize=8, color=col)
ax_waveform.grid(True)
ax_waveform.legend()
# Bottom subplot: display the decoded TX/RX binary data.
ax_text.axis("off") # Turn off axis lines/ticks.
text_str = f"Packet {packet_index + 1}:\n TX: {tx_data}\n RX: {rx_data}"
ax_text.text(0.01, 0.5, text_str, fontsize=14, verticalalignment="center",
transform=ax_text.transAxes)
ax_text.set_title("Decoded Binary Data (TX / RX)")
plt.xlabel("Time")
plt.tight_layout()
plt.show()
if(0):
process_rs485_signal('controller-firmware/python/src/sandbox/analog.csv',
'controller-firmware/python/src/sandbox/fanuc_rs485_detected_edges.csv',
edge_threshold=0.5, # adjust as needed
low_threshold=1.6, # adjust as needed
high_threshold=2.5) # adjust as needed
# =============================================================================
# Example usage:
#
# decoded_packets = decode_rs485_packets(
# edges_csv = 'controller-firmware/python/src/sandbox/fanuc_rs485_detected_edges.csv',
# packet_gap_threshold = 50e-6, # Adjust this threshold (in seconds) based on your capture
# bit_interval = 1/2.72727272e6 # Adjust the bit_interval (in seconds) to your protocol's timing
# )
# for idx, (tx, rx) in enumerate(decoded_packets):
# print(f"Packet {idx}: TX = {tx}, RX = {rx}")
# =============================================================================
# =============================================================================
# Example usage:
#
# Assuming you have:
# - 'analog_capture.csv' with columns "time", "voltage"
# - 'detected_edges.csv' with columns "time", "level"
# - decoded_packets: a list of (tx_data, rx_data) tuples obtained from your decoder
#
decoded_packets = decode_rs485_packets(
edges_csv = 'controller-firmware/python/src/sandbox/fanuc_rs485_detected_edges.csv',
packet_gap_threshold = 50e-6,
bit_interval = 1/2.7272727e6
)
# remove empty packets
decoded_packets = [p for p in decoded_packets if p[0] and p[1]]
# ensure packet is correct length by repeating the last bit as needed
for idx, (tx, rx) in enumerate(decoded_packets):
if len(rx) == 0:
continue
l = 101
if len(rx) < l:
rx += rx[-1] * (l - len(rx))
decoded_packets[idx] = (tx, rx)
for idx, (tx, rx) in enumerate(decoded_packets):
print(f"Packet {idx}: TX = {tx}, RX = {rx}")
# visualize_single_packet('controller-firmware/python/src/sandbox/analog.csv',
# 'controller-firmware/python/src/sandbox/fanuc_rs485_detected_edges.csv',
# decoded_packets,
# packet_index=888,
# packet_gap_threshold=50e-6)
# =============================================================================
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