SBUS2-Telemetry GPS SBS-02G

GPS SBS-02G

Open magnum3131 opened this issue 2 years ago • 33 comments

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

Mar 03 '22 17:03 magnum3131

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

grafik

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?

Mar 07 '22 13:03 ericlangel

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

Mar 07 '22 18:03 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

Mar 08 '22 21:03 magnum3131

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

Mar 09 '22 07:03 ericlangel

Hi Eric,

I'll do that ASAP

Mar 14 '22 19:03 magnum3131

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.

Mar 15 '22 13:03 tschneider1

Hi,

Here the detail of SBS02G slot

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

Mar 17 '22 20:03 magnum3131

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

Mar 18 '22 11:03 tschneider1

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?

Mar 18 '22 12:03 ericlangel

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

Julien

Mar 18 '22 13:03 magnum3131

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

Mar 18 '22 13:03 tschneider1

Hi Tom,Yes this is how i decode the trameJulienLe 18 mars 2022 14:20, tschneider1 @.***> a écrit :

Hi Julien,

Tom

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Mar 18 '22 13:03 magnum3131

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

Mar 18 '22 13:03 tschneider1

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

Mar 18 '22 17:03 ericlangel

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

Mar 18 '22 17:03 magnum3131

It looks like the data is stored in decimal degree and the scale is 0.000001666667

N 55°55.4432 = 55.924050 (bit 26, 33554432) N 27°57.7216 = 27.577216 (bit 25, 16777216) N 13°58.8608 = 13.981 (bit 24, 8388608) N 6°59.4304 = 6.9905 (bit 23, 4194304) N 3°29.7152 = 3.49525 (bit 22, 2097152) N 1°44.8576 = 1.747617 (bit 21, 1048576) N 0°52.4288 = 0.8738 (bit 20, 524288)

bit 26 asserted (33554432 * 0.000001666667 = 55.924050) bit 25 asserted (16777216 * 0.000001666667 = 27.577216) .... bit 20 asserted ( 524288 * 0.000001666667 = 0.873813508)

I'm off for the rest of the weekend. I'll post on Monday with pseudo code for converting from SBUS to latitude.

Mar 19 '22 12:03 tschneider1

Hi Julien,

I'm back at my computer, do you mind doing a little more fuzzing for me? I have utc, latitude and longitude figured out:

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;
/* latitude/longitude scaling factor */
static const float latLonScale = 0.0000001/0.06;
/* decode latitude/longitude */
float latitude = latLonScale*(((pSrc[8]&0x07)<<23)|(pSrc[7]<<15)|(pSrc[5]<<7)|(pSrc[4]>>1));
bool isSouth = pSrc[8]&0x08;
float longitude = latLonScale*(((pSrc[13]&0x7f)<<20)| (pSrc[11]<<12) | (pSrc[10]<<4) | (pSrc[8]>>4));
bool isWest = pSrc[13]&0x80;
printf("utc time: %02d:%02d:%02d; lat/long: (%.07f%s, %.07f%s)\n", hours, minutes, seconds, latitude, isSouth?"S":"N", longitude, isWest?"W":"E");

Now we need decode speed, alititude and vario:

Speed:

Can you send all zeros except for a one in slot 5 bit 1 and tell us what the display reads?
Can you send all zeros except for a one in slot 4 bit 16 and tell us what the display reads?
Can you send all zeros except for a one in slot 4 bit 9 and tell us what the display reads?

Altitude:

Can you send all zeros except for a one in slot 7 bit 3 and tell us what the display reads?
Can you send all zeros except for a one in slot 7 bit 2 and tell us what the display reads?
Can you send all zeros except for a one in slot 6 bit 4 and tell us what the display reads?

Vario:

Can you send all zeros except for a one in slot 7 bit 15 and tell us what the display reads?
Can you send all zeros except for a one in slot 7 bit 14 and tell us what the display reads?
Can you send all zeros except for a one in slot 7 bit 4 and tell us what the display reads?

Tom

Mar 21 '22 13:03 tschneider1

Hi Tom,

Thanks a lot for your code, i'll try it asap. For the Speed, altitude, vario and pressure i have already implement it, at the end of this post https://github.com/BrushlessPower/SBUS2-Telemetry/issues/42#issuecomment-1071404064

Julien

Mar 21 '22 14:03 magnum3131

Hi Julien,

Are speed, altitude and vario displaying correctly with your code? Jerry mentioned that the scaling factor for altitude is 1/80th of a meter. You're adding 700 to the input value. Which one is correct?

Is there anyway you can fuzz the inputs like we did for latitude? It'd be a nice confirmation that we have all the logic corrrect. After you do that, I can write the send_SBS02G function.

Tom

Mar 21 '22 14:03 tschneider1

Hi Tom,Yes for me speed, altitude, pressure and vario work with the code i postedI am off for the rest of the Day, i'll try to do more test tomorowJulienLe 21 mars 2022 15:51, tschneider1 @.***> a écrit : Hi Julien, Are speed, altitude and vario displaying correctly with your code? Jerry mentioned that the scaling factor for altitude is 1/80th of a meter. You're adding 700 to the input value. Which one is correct? Is there anyway you can fuzz the inputs like we did for latitude? It'd be a nice confirmation that we have all the logic corrrect. After you do that, I can write the send_SBS02G function. Tom

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Mar 21 '22 15:03 magnum3131

Got it. I suspect that the offset of 700 might yield the correct answer for your current altitude; however, it might just be a coincidence.

Mar 21 '22 16:03 tschneider1

Hi,

The 700 is for in case you flight under your altitude of start. According the Futaba SBS02 manual the maximum is -700m. The first altitude send is the 0 for the radio, the altitude is calculated with the difference of the 1st altitude and actual

Julien

Mar 21 '22 16:03 magnum3131

Hi,

For being sure, if my GPS (Tiny GPS++) give me the decimal value of latitude and longitude. What i have to do in order to convert it for sending via BUS2 ?

Thanks Julien

Mar 21 '22 17:03 magnum3131

For the F1675 GPS Sensor i had made different Input Types for Degree Minutes, Decimal Degrees and Degree Minutes Seconds.

i would do the same for SBS-02G

Mar 22 '22 06:03 BrushlessPower

That's what I was thinking as well. Multiple different function signatures to support the different representations.

Julien, I'll need you to fuzz the altitude if we want to get that right. I suspect that it's not as straight forward as subtracting 700. I've seen notes that it is stored in 1/80th of a meter and I would like to confirm that.

Mar 22 '22 12:03 tschneider1

I'm just realizing that this might be difficult to fuzz as the device only gives you a delta from what it thinks it's origin is. You probably have to send a valid lat/lon/alt. Then follow up with same lat/lon with a different altitude.

Mar 22 '22 12:03 tschneider1

Hi,

If there is no offset for altitude you can't have negative value for altitude. I use 700 because of Futaba datasheet

[Speed] About 0km/h~500km/h (~311mph) [Altitude] About -700m~+5,500m (-766yard~+6015yard) ---sensor spec [Vario meter] About -150m/s~+150m/s(-336mph~+336mph)

I'll make a video this evening to show the result, In my test there is no ratio for altitude 1 = 1m

For the DMS conversion to degre decimal i don't the same value with these online converter https://www.latlong.net/degrees-minutes-seconds-to-decimal-degrees N 55°55.4432 = 55.924050 (bit 26, 33554432) => 57.14777778

Julien

Mar 22 '22 17:03 magnum3131

There are three standard formats for lat/lon:

Degrees, Minutes, Seconds (DDD° MM' SS.S")
Degrees and Decimal Minutes (DDD° MM.MMM')
Decimal Degrees (DDD.DDDDD°)

The format the handset displays is Degrees and Decimal Minutes; however, you're trying to convert from Degrees, Minutes, Seconds to Decimal Degrees.

Try this calculator: https://boulter.com/gps/#N%2055%B055.4432%20E%2013%B0%2024%27%2033.9480

Mar 22 '22 17:03 tschneider1

Hi, I remove the offset when i transmit 8191 the radio display 819.1m, according the table this is the max altitude. I have to check because it's seem to be low

Julien

Mar 22 '22 21:03 magnum3131

just some more or less known facts

The Temp Sensor SBS01 is specified for 125°C or 200°C (depends on version). With the SBUS2 protocol you can transmit 16383°C and this Value is displayed. So i wont belive the Specs of the Sensor.

And for the GPS Sensor F1675 and both Varios the altitude is calculated in the radio handset. when you transmit 3000m from the first SBUS2 Frame -> your Hanset will display 0m when you later transmit 3100m -> your handset will display 100m

When you want to decode it you should send all zero's for the first 20,50,100 frames (no idea, maybe the first frame is enough) and after that you can test the single Bits.

for the 700m from the Spec: i belive this is jus a spec on the barometer chip. that it can't measure less than -700m (or the factor in pressure) if you send 3000m from the very first frame, and send later 1000m (or 0m) it think the handset would Display -2000m (or -3000m), because its just a math funktion. but i never tested it. GPS and altitude are sensors which i never needed

Mar 23 '22 07:03 ericlangel

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