TP5 is a 2012 Windows application supplied with the Guangzhou-Tongda LED
destination signs fitted to Yutong buses. It has no preview, so building a
destination list is guess-and-check, and it only runs on Windows.
The bus never talks to TP5 — the sign controller reads a .td5 file off an SD
card, and that is the whole interface. So this replaces the software without
touching any hardware or protocol: it just has to write byte-correct .td5.
Formats reverse-engineered from the sample files and TP5(En).exe, then verified
byte-for-byte:
.td5 the file the bus reads. Fixed-layout binary; each destination block
carries a CRC-16/ARC over block[3..len] and a rand() block id, which
together looked like one 4-byte field because RAND_MAX is 0x7fff.
.tp5 the editable project. Line-based text, UTF-16BE hex strings.
.font the sign's own bitmap fonts, each glyph row XORed with its char code.
The app is one self-contained HTML file: live LED preview at the real sign size
with real scrolling, spreadsheet/CSV import, multi-page destinations, undoable
delete, and export to both .td5 and .tp5.
Verified:
- rebuilds a real 46,080-byte TP5 export byte-for-byte with a recomputed CRC
- all 36 stored CRCs verify against the implementation
- driven through its own UI, re-exporting the real file differs in 7 bytes,
all of them the export timestamp
- running on a real bus: signs and driver's controller both correct
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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