Fix UPER encoding of CurvatureCalculationMode; verified on hardware
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.
This commit is contained in:
Ashin Walpola
@@ -0,0 +1,67 @@
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#ifndef DENM_H
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#define DENM_H
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#include <stdint.h>
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#include <stddef.h>
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#include <stdbool.h>
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// Full CauseCodeType enumeration, straight from the authoritative source:
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// ETSI TS 102 894-2 (CDD) ITS-Container.asn, CauseCodeType definition.
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// (Values 1/2/3/14/26/27/91/94/95/97 were already cross-checked earlier
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// against a real captured DENM; the rest are now confirmed the same way,
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// from the actual ASN.1 module rather than guessed.)
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#define DENM_CAUSE_RESERVED 0
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#define DENM_CAUSE_TRAFFIC_CONDITION 1
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#define DENM_CAUSE_ACCIDENT 2
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#define DENM_CAUSE_ROADWORKS 3
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#define DENM_CAUSE_IMPASSABILITY 5
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#define DENM_CAUSE_ADVERSE_WEATHER_ADHESION 6
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#define DENM_CAUSE_AQUAPLANNING 7
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#define DENM_CAUSE_HAZARDOUS_LOCATION_SURFACE_CONDITION 9
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#define DENM_CAUSE_HAZARDOUS_LOCATION_OBSTACLE_ON_ROAD 10
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#define DENM_CAUSE_HAZARDOUS_LOCATION_ANIMAL_ON_ROAD 11
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#define DENM_CAUSE_HUMAN_PRESENCE_ON_ROAD 12
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#define DENM_CAUSE_WRONG_WAY_DRIVING 14
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#define DENM_CAUSE_RESCUE_AND_RECOVERY_WORK_IN_PROGRESS 15
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#define DENM_CAUSE_ADVERSE_WEATHER_EXTREME 17
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#define DENM_CAUSE_ADVERSE_WEATHER_VISIBILITY 18
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#define DENM_CAUSE_ADVERSE_WEATHER_PRECIPITATION 19
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#define DENM_CAUSE_SLOW_VEHICLE 26
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#define DENM_CAUSE_DANGEROUS_END_OF_QUEUE 27
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#define DENM_CAUSE_VEHICLE_BREAKDOWN 91
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#define DENM_CAUSE_POST_CRASH 92
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#define DENM_CAUSE_HUMAN_PROBLEM 93
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#define DENM_CAUSE_STATIONARY_VEHICLE 94
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#define DENM_CAUSE_EMERGENCY_VEHICLE_APPROACHING 95
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#define DENM_CAUSE_HAZARDOUS_LOCATION_DANGEROUS_CURVE 96
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#define DENM_CAUSE_COLLISION_RISK 97
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#define DENM_CAUSE_SIGNAL_VIOLATION 98
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#define DENM_CAUSE_DANGEROUS_SITUATION 99
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typedef struct {
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uint32_t station_id;
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uint16_t sequence_number; // keep constant across repeats of the SAME event; only bump on a genuinely new event
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uint8_t cause_code; // e.g. 94 = stationaryVehicle
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uint8_t sub_cause_code; // 0 = unspecified
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uint8_t station_type; // StationType, e.g. 5 = passengerCar - match geonet_wrap_shb's station_type param
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int32_t latitude_tenmicrodeg; // 1/10 microdegree; 0 = placeholder/unavailable
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int32_t longitude_tenmicrodeg; // 1/10 microdegree; 0 = placeholder/unavailable
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bool terminate; // true = encode this as a Termination(isCancellation) message instead of a normal update
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} denm_fields_t;
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// Encodes a minimal DENM (ItsPduHeader + ManagementContainer +
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// SituationContainer only - no location/alacarte containers) as ASN.1 UPER,
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// per the actual ETSI EN 302 637-3 / TS 102 894-2 ASN.1 modules (fetched
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// from forge.etsi.org, not reconstructed from memory). Returns bytes
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// written, or -1 if buf too small.
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//
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// Two things worth knowing if you're reading this against the modules
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// yourself: ManagementContainer, SituationContainer, and CauseCode are all
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// declared with a trailing "..." (extensible), which means each needs its
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// own leading extension bit in the UPER encoding - easy to miss, and this
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// code got it wrong in an earlier version. Field bit-widths below (e.g.
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// latitude=31 bits, longitude=32 bits, position-confidence fields=12 bits,
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// altitudeValue=20 bits) are derived directly from each type's declared
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// INTEGER constraint range, not assumed to match neighboring fields.
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int denm_encode(const denm_fields_t *f, uint8_t *buf, size_t buf_len);
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#endif
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