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Third Eye Kit

THE ENGINEERING RECORD, FILE 06 OF 19

The Spine and T.E.K.-Link 0.1

Every file of the recordThe engineering hub
SYNCbyte 0VERbyte 1SEQbyte 2FLAGSbyte 3COLS, eight belt columnsbytes 4 to 11HEADbyte 12GNDbytes 13 to 14MOVERbytes 15 to 16AMPLbyte 17STATEbyte 18CRC8byte 19Offsets in bytes. One frame per control tick; at twenty bytes it fits a Bluetooth notify with room to spare, and the phone link's tens of milliseconds never touch the warning path.
T.E.K.-Link 0.1, twenty bytes per tick. A sync byte, the version 0x01, a rolling counter, flag bits for drop off, mover present and faults, eight belt column distances, the collar distance, the ground and drop off state, the nearest mover's range and bearing, an amplitude summary, the state machine code, and a CRC8 over the first nineteen bytes. Little endian. The team's own format, not a standard. Source: docs/06.

Decision: ESP32-S3 as the Spine for logging and Bluetooth LE to the phone, fed by the Reflex over a one way UART (Reflex TX to Spine RX, no wire back into the Reflex). The Spine never writes into the safety path.

T.E.K.-Link 0.1, project internal, 20 bytes, little endian, one frame per control tick:

Offset Bytes Field Notes
0 1 SYNC frame start marker
1 1 VER protocol version, 0x01
2 1 SEQ rolling counter
3 1 FLAGS drop off, mover present, fault bits
4 8 COLS eight belt column nearest distances
12 1 HEAD collar nearest distance
13 2 GND ground and drop off state
15 2 MOVER nearest mover range and bearing
17 1 AMPL global amplitude summary
18 1 STATE reflex state machine code
19 1 CRC8 over bytes 0 to 18

This is the team's own format, not a standard, and is labeled as such.

Bluetooth realities: iOS minimum connection interval 15 ms with about 4 packets per interval, Android down to 7.5 ms with wide device variance, practical MTU about 185 bytes on iOS, realistic sustained notify throughput far below the 2 Mbps PHY. A 20 byte frame per tick fits easily. The phone link adds tens of milliseconds that never touch the warning path.

Source: docs/06-spine-and-link.md, the engineering record. Every number on this page is read from that file. If a fact is not in the record, it is measured on the bench, or it stays off this site.