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J1939: VP1/VP2 PG fixes #626

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J1939: VP1/VP2 PG fixes #626

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6030189
Update j1939 VP1 repetition rate
SamantazFox May 5, 2026
d5ed235
Update j1939 VP1 parameters ranges
SamantazFox May 5, 2026
9743a2f
Add j1939 VP2 details
SamantazFox May 5, 2026
90383a0
Fill unassigned bytes with 0xFF in J1939 VP2
SamantazFox May 8, 2026
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28 changes: 17 additions & 11 deletions j1939_vehicle_position/j1939_vehicle_position_cmn.h
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ struct j1939_vp_err_msg {
#define J1939_VP1_PRIO_DEFAULT 6
#define J1939_VP1_MAX_TRANSFER_LENGH \
sizeof(struct j1939_vp1_packet)
#define J1939_VP1_REPETITION_RATE_MS 5000
#define J1939_VP1_REPETITION_RATE_MS 1000
#define J1939_VP1_JITTER_MS 500

/**
Expand All @@ -63,17 +63,17 @@ struct j1939_vp_err_msg {
* - Data Length: 4 bytes
* - Resolution: 10^-7 deg/bit
* - Offset: -210 degrees
* - Range: -210 to +211.1008122 degrees
* - Operating Range: -210 degrees (SOUTH) to +211.108122 degrees
* - Range: -210 to +211.10081215 degrees
* - Operating Range: -210 degrees (SOUTH) to +211.1081215 degrees
* (NORTH)
*
* @longitude: Raw longitude position of the vehicle
* - SPN: 585
* - Data Length: 4 bytes
* - Resolution: 10^-7 deg/bit
* - Offset: -210 degrees
* - Range: -210 to +211.1008122 degrees
* - Operating Range: -210 degrees (WEST) to +211.108122 degrees
* - Range: -210 to +211.10081215 degrees
* - Operating Range: -210 degrees (WEST) to +211.1081215 degrees
* (EAST)
*
* This structure defines each component of the Vehicle Position as described in
Expand Down Expand Up @@ -142,42 +142,48 @@ j1939_vp1_set_longitude(struct j1939_vp1_packet *packet, int32_t longitude)
/**
* struct j1939_vp2_packet - Represents the PGN 64502 Vehicle
* Position 2 packet
* FIXME: current packet layout is guessed based on limited information:
* https://www.isobus.net/isobus/pGNAndSPN/10801?type=PGN
*
* @total_satellites: Total number of satellites in view
* - SPN: 8128
* - Data Length: 1 byte
* - Range: 0 to 250
*
* @hdop: Horizontal dilution of precision
* - SPN: 8129
* - Data Length: 1 byte
* - Resolution: 0.1
* - Range: 0.0 to 25.0
*
* @vdop: Vertical dilution of precision
* - SPN: 8130
* - Data Length: 1 byte
* - Resolution: 0.1
* - Range: 0.0 to 25.0
*
* @pdop: Position dilution of precision
* - SPN: 8131
* - Data Length: 1 byte
* - Resolution: 0.1
* - Range: 0.0 to 25.0
*
* @tdop: Time dilution of precision
* - SPN: 8132
* - Data Length: 1 byte
* - Resolution: 0.1
* - Range: 0.0 to 25.0
*
* This structure defines each component of the Vehicle Position 2 as described
* in PGN 64502.
*/
struct j1939_vp2_packet {
uint8_t total_satellites; /* SPN 8128 */
uint8_t hdop; /* SPN 8129 */
uint8_t vdop; /* SPN 8130 */
uint8_t pdop; /* SPN 8131 */
uint8_t tdop; /* SPN 8132 */
uint8_t hdop; /* SPN 8129 */
uint8_t vdop; /* SPN 8130 */
uint8_t pdop; /* SPN 8131 */
uint8_t tdop; /* SPN 8132 */
uint8_t unused5; /* Always 0xFF */
uint8_t unused6; /* Always 0xFF */
uint8_t unused7; /* Always 0xFF */
} __attribute__((__packed__));

/**
Expand Down
6 changes: 6 additions & 0 deletions j1939_vehicle_position/j1939_vehicle_position_srv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -270,6 +270,12 @@ static int j1939_vp2_get_data(struct j1939_vp_srv_priv *priv,
j1939_vp2_set_pdop(vp2p, pdop);
j1939_vp2_set_tdop(vp2p, tdop);

/* This PG's last 3 bytes are not assigned and hence must be set
* to 0xFF as per J1939-71, section 5.2 */
vp2p->unused5 = 0xFF;
vp2p->unused6 = 0xFF;
vp2p->unused7 = 0xFF;

return 0;
}

Expand Down
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