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cVEND is the NFC reader on the bottom half of the PM3
cVEND protocol notes
Reader -> Host
packet type 0xED seems to be a log message:
\xBC\xB9\0\xED\0h\xB6\x0306:48:13 Error: feclr_transceive() failed: error: 0, status: 0x00000008
0xB9 - card read?
Host -> reader
0xBC - appears after every read (ack of some sort?)
Card read flow
R: BCB600B9000BBB0C000000048A6EF29B149079CB8CF0 H: BC2200BC000158602A714F60 R: BCB722BD001E3D00000401013300160504010103001605048A6EF29B149020487330305022C98C7E9B H: BC2300BC0004AA5A2BC3F911A8A56A R: BCB823BD0002E301FDE0523164
Another one:
R: BCBF00B9000B480C000000048A6EF29B149079CB8CF0 H: BC2400BC0001C4602A714F60 R: BCC024BD001E0800000401013300160504010103001605048A6EF29B149020487330305022C98C7E9B H: BC2500BC0004365A2BC3F911A8A56A R: BCC125BD00027401FDE0523164
Sample log message:
BCB000ED0068450330363A34383A3038204572726F723A206665636C725F7472616E7363656976652829206661696C65643A206572726F723A20302C207374617475733A2030783030303030303038200A205B524649445265616465724D756C74694170702E6370703A3135395D0002CD1533BCB100ED0046B40130363A34383A3038207472616E7363656976652065
00000000 bc b0 00 ed 00 68 45 03 30 36 3a 34 38 3a 30 38 |¼°.í.hE.06:48:08| 00000010 20 45 72 72 6f 72 3a 20 66 65 63 6c 72 5f 74 72 | Error: feclr_tr| 00000020 61 6e 73 63 65 69 76 65 28 29 20 66 61 69 6c 65 |ansceive() faile| 00000030 64 3a 20 65 72 72 6f 72 3a 20 30 2c 20 73 74 61 |d: error: 0, sta| 00000040 74 75 73 3a 20 30 78 30 30 30 30 30 30 30 38 20 |tus: 0x00000008 | 00000050 0a 20 5b 52 46 49 44 52 65 61 64 65 72 4d 75 6c |. [RFIDReaderMul| 00000060 74 69 41 70 70 2e 63 70 70 3a 31 35 39 5d 00 02 |tiApp.cpp:159]..| 00000070 cd 15 33 bc b1 00 ed 00 46 b4 01 30 36 3a 34 38 |Í.3¼±.í.F´.06:48| 00000080 3a 30 38 20 74 72 61 6e 73 63 65 69 76 65 20 65 |:08 transceive e|
There are 4 bytes appended at the end of some messages (presumably those with ID LSB=1, if the Rust struct description is accurate?) which is not a CRC32 with any polynomial I recognize, but a CRC32 of (message + CRC) is always 0xFFFFFFFF. These 4 bytes are NOT included in the length.
The checksum is _appended_, as can be seen by it following the log message (after the final \0).
is it a _little endian_, _bit negated_ CRC32. Which is weird because the length is big endian?..
* Host only sends two types of messages after initialization - both of type 0xBC. One is length 1 and the body is always 0x60 (+ negated CRC 2A714F60), the other is of length 4 and the body is always 5A2BC3F9 (+ negated-CRC 11A8A56A)
