9756538f16
Organizes 11 projects for Cerbo GX/Venus OS into a single repository: - axiom-nmea: Raymarine LightHouse protocol decoder - dbus-generator-ramp: Generator current ramp controller - dbus-lightning: Blitzortung lightning monitor - dbus-meteoblue-forecast: Meteoblue weather forecast - dbus-no-foreign-land: noforeignland.com tracking - dbus-tides: Tide prediction from depth + harmonics - dbus-vrm-history: VRM cloud history proxy - dbus-windy-station: Windy.com weather upload - mfd-custom-app: MFD app deployment package - venus-html5-app: Custom Victron HTML5 app fork - watermaker: Watermaker PLC control UI Adds root README, .gitignore, project template, and per-project .gitignore files. Sensitive config files excluded via .gitignore with .example templates provided. Made-with: Cursor
87 lines
2.9 KiB
Python
87 lines
2.9 KiB
Python
#!/usr/bin/env python3
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"""Find offsets that show consistent heading-like values in BOTH pcaps."""
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import struct
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from collections import defaultdict
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def decode_float(data, offset):
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if offset + 4 > len(data):
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return None
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try:
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val = struct.unpack('<f', data[offset:offset+4])[0]
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if val != val:
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return None
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return val
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except:
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return None
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def read_pcap(filename):
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packets = []
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with open(filename, 'rb') as f:
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header = f.read(24)
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magic = struct.unpack('<I', header[0:4])[0]
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swapped = magic == 0xd4c3b2a1
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endian = '>' if swapped else '<'
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while True:
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pkt_header = f.read(16)
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if len(pkt_header) < 16:
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break
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ts_sec, ts_usec, incl_len, orig_len = struct.unpack(f'{endian}IIII', pkt_header)
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pkt_data = f.read(incl_len)
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if len(pkt_data) < incl_len:
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break
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if len(pkt_data) > 42 and pkt_data[12:14] == b'\x08\x00':
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ip_header_len = (pkt_data[14] & 0x0F) * 4
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payload_start = 14 + ip_header_len + 8
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if payload_start < len(pkt_data):
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packets.append(pkt_data[payload_start:])
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return packets
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# Load both pcaps
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pcap1 = read_pcap("raymarine_sample.pcap")
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pcap2 = read_pcap("raymarine_sample_twd_69-73.pcap")
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print("Looking for offsets where values differ significantly between captures")
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print("(indicating actual sensor data that changed, like heading)\n")
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# Focus on 344 and 446 byte packets (most common with wind data)
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for target_size in [344, 446]:
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print(f"\n{'='*70}")
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print(f"PACKET SIZE: {target_size} bytes")
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print("=" * 70)
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pkts1 = [p for p in pcap1 if len(p) == target_size][:10]
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pkts2 = [p for p in pcap2 if len(p) == target_size][:10]
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if not pkts1 or not pkts2:
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print(" Not enough packets")
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continue
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print(f"\n{'Offset':<10} {'Original pcap':<20} {'TWD pcap':<20} {'Diff':<10}")
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print("-" * 60)
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# Check offsets from 0x50 to 0x180
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for offset in range(0x50, min(target_size - 4, 0x180)):
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vals1 = [decode_float(p, offset) for p in pkts1]
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vals2 = [decode_float(p, offset) for p in pkts2]
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# Filter valid radian values (0 to 2*pi)
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degs1 = [v * 57.2958 for v in vals1 if v and 0 < v < 6.5]
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degs2 = [v * 57.2958 for v in vals2 if v and 0 < v < 6.5]
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if not degs1 or not degs2:
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continue
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avg1 = sum(degs1) / len(degs1)
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avg2 = sum(degs2) / len(degs2)
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diff = abs(avg2 - avg1)
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# Look for offsets where:
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# 1. Values are valid angles (not 0, not garbage)
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# 2. Values changed between captures (diff > 5°)
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# 3. Both values are in reasonable heading range (0-360°)
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if 5 < avg1 < 355 and 5 < avg2 < 355 and diff > 5:
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print(f"0x{offset:04x} {avg1:6.1f}° ({len(degs1)} hits) {avg2:6.1f}° ({len(degs2)} hits) {diff:5.1f}°")
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