GPS SBS-02G

[magnum3131]

Hi,

I'm working on the code to adding the GPS sensor SBS-02G. For the moment i manage to send the altitude, variometer and the pressure. But i'm stuck by the latitude and the longitude.

The latitude is coded on 26 bit wich can have the maximum value 67 108 864, insuffisant for 90°. According to my test the value of the bit is not always a power of 2.
Here the detail of the 26 bit :
55554432, 27577216, 13588608, 6594304, 3297152, 1448576, 524288, 262144, 131072, 65536, 32768, 16384, 8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1

Same thing with the longitude but this time with 27 bit :
111508864, 55554432, 27577216, 13588608, 6594304, 3297152, 1448576, 524288, 262144, 131072, 65536, 32768, 16384, 8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2,1

I tried to make a fonction to convert value with this bit but the radio display different value. Depending on the case i have the following difference between the send value and the display.
2400000, 2000000, 1600000, 1200000, 800000, 400000, 0

The difference depend of the coordonate

Have you ever seen this king of compression to transmit high value with less bit ?

Thanks

[ericlangel]

Did you had a look the Site of Alex K.?
https://sites.google.com/site/sbus2diy/home/sbus2protocol-part2/sbus2protocol-part3

The SBS-02G could be the same Format as SBS-01G

Please give us more informations:
how much slots?
where is altitude, vario and preassure located?
did you have a SBS-02G for decoding?

[magnum3131]

Hi Eric,

Yes i have a SBS-02G for testing, i use your library to view the data in each slot. The SBS use 8 slot
Slot 0 = Date not display on radio, i didn't work on it yet
Slot 1 & 2 = 26 bit for latitude + 1 bit for pole(0 North, 1 South) + 4bit of longitude + 1bit i don't know
Slot 3 & 4 = 23bit for longitude (27 total with slot 1&2) + 1 bit for pole + 8 bit of speed
Slot 5 & 6 & 7 = Mix for Speed, Pressure, Alti and Vario

I already done the code for the pressure, alti & vario and it's working on 18MZ

I'm not to my home this evening, i don't have access to my detail note with the detail of each bit

Thanks

[magnum3131]

Hi,

Here the detail of slot

Slot 1
Latitude
16384 8192 4096 2048 1024 512 256 128 | 64 32 16 8 4 2 1 ?

Slot 2
Latitude
8 4 2 1 Pole 55554432 27577216 13588608 | 6594304 3297152 1448576 524288 262144 131072 65536 32768
Longitude

Slot 3
Longitude
524288 262144 131072 65536 32768 16384 8192 4096 | 2048 1024 512 256 128 64 32 16

Slot 4
Longitude
128 64 32 16 8 4 2 1 | Pole 111508864 55554432 27577216 13588608 6594304 3297152 1448576
Speed

Slot 5
Speed
1024 512 256 128 64 32 16 8 | 4 2 1 ? ? ? 256 ?
Pressure

Slot 6
Pressure
4096 2048 1024 512 256 128 64 32 | 16 8 4 2 1 8192 4096 2048
Altitude

Slot 7
Altitude
? 2048 1024 512 256 128 64 32 | 16 8 4 2 1 32768 16384 8192
Vario

[ericlangel]

it's hard to understand your coding

try to make it readable in a Table

Slot Number	High Byte	Low Byte	Comment
Slot 0	Time/Date	Time/Date	no work done
Slot 1	LAT Bit 8-15 ?	LAT Bit 0-7	Slot 1 should contain a Date Time Bit in High Byte
Slot 2	LAT Bit 16-23?	LON Bit 0-4 ; Pole ; LAT Bit 24 -26	not sure
Slot 3
Slot 4
Slot 5
Slot 6
Slot 7

could you try it this way?

and it would be good to have a Log of the Sensor
Which Bytes are in the Slots?
And what is displayed to the 18MZ?

The SBS-01G and SBS-02G are strange. But maybe we could get it decoded together

[magnum3131]

Hi Eric,

I'll do that ASAP

[tschneider1]

I'm willing to help as well. I am also attempting to decode the data off an SBS-02G. I have the GPS module attached to an r7008sb which is talking to a T14SG. Happy to post some logs and write some code.

UTC is pretty straight forward. There was a comment on Jerry Chapman's blog (http://sbustelemetrysensors.blogspot.com) that described it clearly. Here is what that looks like:

static const uint8_t pSrc[24] = {0x13,0x53,0x1A, 0x93,0x71,0xD0, 0x53,0xDE,0xE2, 0xD3,0xAF,0xD7, 0x33,0xBF,0x00, 0xB3,0x2E,0x30, 0x73,0xBC,0xBB, 0xF3,0xE2,0xAE};
uint32_t seconds = pSrc[1] | (pSrc[2]<<8) | ((pSrc[4]&0x01)<<16);
uint32_t hours = 0.5 + floor(float(seconds) / 3600.0);
seconds -= 3600 * hours;
uint32_t minutes = 0.5 + floor(float(seconds)/60.0);
seconds %= 60;
printf("utc time: %02d:%02d:%02d\n", hours, minutes, seconds);

utc time: 20:04:35

I've had trouble parsing out his lat/lon though. He says his location is N 41:07.8440, W110:34.3932. Which should be buried in that array; however, I cannot seem to pull it out using Alex's table.

[magnum3131]

Hi,

Here the detail of SBS02G slot

<style> </style>

Slot Number	High Byte								Low Byte
	16	15	14	13	12	11	10	9	8	7	6	5	4	2	2	1
0	?	?	?	?	?	?	?	?	?	?	?	?	?	?	?	?
1	LAT 16384	LAT 8192	LAT 4096	LAT 2048	LAT 1024	LAT 512	LAT 256	LAT 128	LAT 64	LAT 32	LAT 16	LAT 8	LAT 4	LAT 2	LAT 1	?
2	LON 8	LON 4	LON 2	LON 1	LAT Pôle 0 = N 1 = S	LAT 55554432	LAT 27577216	LAT 13588608	LAT 6594304	LAT 3297152	LAT 1448576	LAT 524288	LAT 262144	LAT  131072	LAT 65536	LAT  32768
3	LON 524288	LON 262144	LON  131072	LON 65536	LON  32768	LON 16384	LON 8192	LON 4096	LON 2048	LON 1024	LON 512	LON 256	LON 128	LON 64	LON 32	LON 16
4	SPEED 128	SPEED 64	SPEED 32	SPEED 16	SPEED 8	SPEED 4	SPEED 2	SPEED 1	LON Pôle 0 = E 1 = W	LON 111508864	LON 55554432	LON 27577216	LON 13588608	LON 6594304	LON 3297152	LON 1448576
5	Pressure 1024	Pressure 512	Pressure 256	Pressure 128	Pressure 64	Pressure 32	Pressure 16	Pressure 8	Pressure 4	Pressure 2	Pressure 1	?	GPS SIGNAL	GPS SIGNAL	Set 1 For Speed	SPEED 256
6	Alti 4096	Alti 2048	Alti 1024	Alti 512	Alti 256	Alti 128	Alti 64	Alti 32	Alti 16	Alti 8	Alti 4	Alti 2	Alti 1	Pressure 8192	Pressure 4096	Pressure 2048
7	?	Vario 2048	Vario 1024	Vario 512	Vario 256	Vario 128	Vario 64	Vario 32	Vario 16	Vario 8	Vario 4	Vario 2	Vario 1	Pressure 32768	Pressure 16384	Pressure 8192

Here a begining of function that work with Speed, Vario, altitude, Pressure, GPS signal (Full 3 bar)
I put slot latitude and longitude slot with generic value that display on T18
Latitude = N 70°05.3425
Longitude = E 1°27.6435

Slot 9
bytes[1] = 0x62;
bytes[2] = 0x5E;
Slot 10
bytes[1] = 0x03;
bytes[2] = 0x35;
Slot 11
bytes[1] = 0xF9;
bytes[2] = 0xD5;

Here the code
SBUS2.h
void send_SBS02G(uint8_t port, int16_t pressure, int16_t alti, int16_t vario, int16_t speed, int32_t latitude, int32_t longitude);

SBUS2.cpp
`void send_SBS02G(uint8_t port, int16_t pressure, int16_t alti, int16_t vario, int16_t speed, int32_t latitude, int32_t longitude){
int16_t value = 0;

uint8_t bytes[SBUS2_TEL_DATA_SIZE] = {0x03, 0x40, 0x00 };
uint8_t bytes9[SBUS2_TEL_DATA_SIZE] = {0x03, 0x40, 0x00 };
uint8_t bytes10[SBUS2_TEL_DATA_SIZE] = {0x03, 0x40, 0x00 };

bytes[1] = 0xFF;
bytes[2] = 0xFF;
//bytes[1] = 0x0B;
//bytes[2] = 0x9A;
SBUS2_transmit_telemetry_data( port , bytes);

bytes9[1] = 0x62;
bytes9[2] = 0x5E;
bytes10[1] = 0x03;
bytes10[2] = 0x35;

SBUS2_transmit_telemetry_data( port+1 , bytes9);
SBUS2_transmit_telemetry_data( port+2 , bytes10);

bytes[1] = 0xF9;
bytes[2] = 0xD5;
SBUS2_transmit_telemetry_data( port+3 , bytes);

bytes[1] = 0x00;
bytes[2] = speed;
SBUS2_transmit_telemetry_data( port+4 , bytes);

//PRESSURE
value = pressure;
speed = speed >> 8;
//speed = speed << 1;
bytes[1] = value << 5;// >> 8;
bytes[1] = bytes[1] | speed;
bytes[1] = bytes[1] | 0x0E; //signal GPS
bytes[2] = pressure >> 3;
SBUS2_transmit_telemetry_data( port+5 , bytes);

pressure = pressure >> 8;
pressure = pressure << 2;
pressure = pressure & 0xE0;
pressure = pressure >> 5;

//ALTITUDE
alti = (alti + 700);
value = alti;
bytes[1] = value << 3;
bytes[1] = bytes[1] | pressure;
bytes[2] = alti >> 5;
SBUS2_transmit_telemetry_data( port+6 , bytes);
alti = alti >> 13;

//VARIO
value = (vario + 1500);
bytes[1] = value << 3;
bytes[1] = bytes[1] | alti;
value = (vario + 1500);
bytes[2] = value >> 5;
bytes[2] = bytes[2] | 0x80;
SBUS2_transmit_telemetry_data( port+7 , bytes);
}`

Exemple of call
send_SBS02G(8, (int16_t)10084,(int16_t)100,(int16_t)25,(int16_t)300,(int32_t)(0),(int32_t)(0));

Julien

[tschneider1]

Hi Julien,

Can you confirm that higher MSB's of latitude and longitude are non powers of two? That seems strange.

For instance:

Bit 4 of slot 2 is a power of two (524288); however, Bit 5 of slot 2 is not (1448576)

Tom

[ericlangel]

Thats something i dont understand in juliens table and text's

what are these Numbers?

normally we need a table like this

Slot x Bit 0 = LAT Bit 6
Slot x Bit 1 = LAT Bit 7
and so on

a number like 262144 ....is 2^18 -> so does that mean its Bit 18?

[magnum3131]

Hi,

On the table i gave the name and number represent the field and the value display by the radio.

For example:
Slot 2 Bit 16 display a Longitude E 0°00.0008 on the radio

Tom, yes Higher MSB on latitude and longitude are not a power of 2

Latitude on 26 bit :
55554432, 27577216, 13588608, 6594304, 3297152, 1448576, 524288, 262144, 131072, 65536, 32768, 16384, 8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1

Longitude on 27 bit :
111508864, 55554432, 27577216, 13588608, 6594304, 3297152, 1448576, 524288, 262144, 131072, 65536, 32768, 16384, 8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2,1

I tried to make a fonction to convert value with this bit but the radio display different value. Depending on the case i have the following difference between the send value and the display.
2400000, 2000000, 1600000, 1200000, 800000, 400000, 0

Julien

[tschneider1]

Hi Julien,

I think I am starting to understand. Are you fuzzing the transceiver and monitoring the output of the display? You're saying you're sending all zeros except for slot 2 bit 16 and the longitude displays E 0°00.0008?

Tom

[magnum3131]

Hi Tom,Yes this is how i decode the trameJulienLe 18 mars 2022 14:20, tschneider1 ***@***.***> a écrit : Hi Julien, I think I am starting to understand. Are you fuzzing the transceiver and monitoring the output of the display? You're saying you're sending all zeros except for slot 2 bit 16 and the longitude displays E 0°00.0008? Tom —Reply to this email directly, view it on GitHub, or unsubscribe.Triage notifications on the go with GitHub Mobile for iOS or Android. You are receiving this because you authored the thread.Message ID: ***@***.***>

[tschneider1]

Got it, I suspect you are rolling the scaling value into the table.

Can you do a little fuzzing and let us know what the display says? Let's start by trying to figure out the latitude...

• Can you send all zeros except for a one in slot 2 bit 11 and tell us what the display reads?
• Can you send all zeros except for a one in slot 2 bit 10 and tell us what the display reads?
• Can you send all zeros except for a one in slot 2 bit 5 and tell us what the display reads?

Tom

[ericlangel]

maybe this helps:

// coordinates Berlin TV Tower = Degree Minutes = Decimal Degrees = Degree Minutes Seconds
int32_t latitude = 52312499; // = N 52° 31.2499 = N 52.520833 = N 52° 31' 14.9988"
int32_t longitude = 13245658; // = E 13° 24.5658 = E 13.409430 = E 13° 24' 33.9480"

This coordinates are exactly the same position, but they are expressed in different formats

The other decoded gps sensor uses degreeminutes as input type, but displays as degree minutes seconds

[magnum3131]

Hi,

Can you send all zeros except for a one in slot 2 bit 11 and tell us what the display reads? => N 55°55.4432
Can you send all zeros except for a one in slot 2 bit 10 and tell us what the display reads? => N 27°57.7216
Can you send all zeros except for a one in slot 2 bit 5 and tell us what the display reads? => N 0°52.4288

Julien