Ashin WalpolaandClaude Opus 5
528637dab6
CurvatureCalculationMode is the one extensible ENUMERATED in CAM:
ENUMERATED {yawRateUsed(0), yawRateNotUsed(1), unavailable(2), ...}
UPER encodes an extensible ENUMERATED as an extension bit followed by the root
index - 1 + 2 = 3 bits. All three of our encoders wrote only the 2-bit index,
shifting yawRate and the entire low-frequency container one bit early for any
standards-compliant receiver.
It went unnoticed because every end of this project shared the mistake: the
Kotlin codec was ported bit-for-bit from cam.c, so phone and ESP32 agreed
perfectly with each other and with nothing else. Confirmed against the ETSI
ASN.1 in the C-ITS-Parser checkout, where rasn marks this type - and only this
type - #[non_exhaustive].
Fixed in all three copies of the encoder (app CamUperCodec.kt,
obu-firmware/main/cam.c, obu-cam-transmistter/main/cam.c) plus the decoder,
which now rejects rather than misreads a set extension bit. Frame size is
unchanged at 43 bytes. Transmitter reflashed and the phone decodes its CAMs.
Also in this change:
- serial_link: skip send_frame entirely when no USB host is attached, and raise
the tx mutex timeout above the worst-case hold. With the phone unplugged every
write blocked its full timeout while holding the lock, so forwarded CAM_RX
traffic starved the 1 Hz heartbeat - observed as "tx mutex timeout, dropping
frame" on the console, and it would have tripped the phone's link watchdog.
Verified gone on hardware.
- Log decoded and failed CAMs in CamUseCaseRepository. "The app shows nothing"
had two indistinguishable causes; a silent `?: return` made this bug much
harder to find than it needed to be.
- Remove the ESP32 send-only/send-and-receive toggle. Reception can't be
disabled in firmware (raw TX only works while promiscuous), so it was an
app-side filter pretending to be a radio control.
- V2X monitor follows the serial link state on the ESP32 path instead of MQTT,
which is permanently disconnected there; CAM intake is gated on the link being
up, and engine state is cleared when it drops.
- About screen: 0.5.0, Phase 03.
- Track obu-cam-transmistter, the bench CAM transmitter. Its cam.c is compiled
(unlike obu-firmware's reference copy) and must stay bit-identical to the other
two - this commit is what that coupling costs when it's broken.
- Document the two-toolchain split: this project builds on IDF 5.5.4, obu-firmware
on the pinned 6.1. Exporting both in one shell fails confusingly.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
36 lines
1.7 KiB
C
36 lines
1.7 KiB
C
#ifndef CAM_H
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#define CAM_H
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#include <stdint.h>
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#include <stddef.h>
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// Minimal CAM (Cooperative Awareness Message) per ETSI EN 302 637-2 v1.4.1
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// (CAM-PDU-Descriptions) + TS 102 894-2 v1.3.1 (CDD / ITS-Container), matching
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// the field set the working Rust reference (esp32-c_its-companion, feat/tx-cam,
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// src/applogic/cam_tx.rs) transmits:
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// - ItsPduHeader (protocolVersion 2, messageID 2 = cam)
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// - CoopAwareness { generationDeltaTime, camParameters }
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// - CamParameters {
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// basicContainer { stationType, referencePosition },
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// highFrequencyContainer = basicVehicleContainerHighFrequency { ... },
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// lowFrequencyContainer = basicVehicleContainerLowFrequency { ... }
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// }
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// All vehicle-dynamics fields we don't measure are encoded as their ASN.1
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// "unavailable" value. Speed is a real 0 (correct for a stationary station).
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typedef struct {
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uint32_t station_id;
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uint8_t station_type; // StationType(0..255): 5 = passengerCar
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uint16_t generation_delta_time; // TimestampIts mod 65536 (ms); 0 until a real clock is wired
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int32_t latitude_tenmicrodeg; // Latitude, 1/10 microdegree
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int32_t longitude_tenmicrodeg; // Longitude, 1/10 microdegree
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uint16_t speed_cm_s; // SpeedValue, 0.01 m/s units (0 = stationary)
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uint16_t heading_ddeg; // HeadingValue, 0.1 deg units (0..3600), 3601 = unavailable
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uint16_t vehicle_length_dm; // VehicleLengthValue(1..1023), 10cm steps
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uint8_t vehicle_width_dm; // VehicleWidth(1..62), 10cm steps
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} cam_fields_t;
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// Encodes the CAM as ASN.1 UPER. Returns bytes written, or -1 if buf too small.
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int cam_encode(const cam_fields_t *f, uint8_t *buf, size_t buf_len);
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#endif
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