Roll corrected RTK position from AOG to other Devices with serial RS232

What would it need? How could it be realized to get the rtk and roll corrected and centered (if using dual) antenna position out of AOG and make it available to an isobus terminal (e.g. CCI) via the serial interface. E.g. CCI needs NMEA sentences GGA, RMC, VTG (with 5 Hz) and GSA (with 1 Hz).

I’ve been working on this, actually. At least before the season started. Requires a Teensy, the F9P, and a BNO08x. I based my work loosely on how AOG does it, along with the new experimental PANDA code that uses the BNO08x in RVC mode. When I get some time to breath, I’ll see if I can get the code into a functional state. My purpose in doing this was to try to generate some isobus CAN bus position messages, but also RS232 output as well. It was mostly working when last I worked on it. Reverse detection has proved to be very difficult. That’s kind of important if you’re mapping with isobus.

I tested highly experimental code this spring (from someone else) that used AoG’s corrected & center position to output gga & vtg. It worked except it has a rounding/precision issue that I have not had time to further investigate.

It outputs to UDP so a RS232 Serial Ethernet Server works well


@CommonRail has documented the ISOBUS messages needed to feed an ISOBUS monitor. It wouldn’t be too difficult to make a little teensy with RS232 input that parsed the corrected GGA and VTG coming from AOG (using the experimental code) and generate the CAN messages.

That sounds awesome. I’d love to try it this fall for anhydrous application

I believe he already has code that outputs canbus messages for the corrected AoG position.

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Yes I had forgotten about that.

I need to do some more research, but the dual GPS code seem to lose precision. I think it’s due to the amount of calculation that needs to be done. When I zoom in all the way in AOG, I see the tractor jitter a bit. We are using mtz8302 dual GPS code.

For interests sake, we have a F9P to RS-232 converter. It’s a work in progress, the end result will be a dual F9P sending UDP to AOG and RS-232 to any other devices needing GPS. The ESP32 code needs some more fine tuning, like should the RS-232 message be retrieved before the dual GPS code (for precision), or should the corrected position be sent for easier implementation on the RS-232 device?

Dual GPS Serial Rev (274.4 KB) Remove the .zip extension to open in Fritzing

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This variant has charm to me. Hm, but how much time is passing by, the signal from f9p goes to teensy to AGIO to AOG (correction calculation) and back to AGIO … ?

I think Franz Husch has already done the same (dual f9ps with two esp32 - one does the calculation and provides the info to AOG. The other esp can provide the corrected information to a AMATRON from AMAZONE. Sorry, for now I don’t find the link to his software.

The Teensy has more than enough power to do the correction calculations.

How do you tell the teensy what height the antenna is at? I think we can’t always assume that the antenna height can be hard coded in the code.

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As far as I know, for systems with Teensy, the antenna height etc. must be entered into AGIO. This is how I did it with my V4.1 mirco board. I also have a second dual system with ESP32 and code from Franz Husch. Everything is entered there in the sketch. I personally like this better.

In fact, it would be nice if in the future the Teensy could output the corrected position for dual systems via RS232.

An RS232 interface on the AIO micro/standard board should be possible.

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Does anybody have a proben solution for getting Roll corected RTK NMEA from dual F9P setup to a precision planting 20/20 ?

I’d like this also. I’m currently keeping our CRG receiver around just for the purpose of having roll corrected nmea for the 20/20, and our NH3 rate controller.

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seems like the tractor would already be getting roll corrected data from the Dual board? Just a matter of sending it out from the teensy on a serial port.

The roll correction is applied in AOG so it needs to output the corrected position back out via AgIO->UDP->Teensy->Serial. How much roll correction is needed for the 20/20 to do it’s job and how different is the tractor’s roll from the implement?

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I’m running single with a BNO, but if there was a good way to get it with dual, I would definitely switch.

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The scenario that causes the most problems for us, is when you planting a ditch or terrace bottom. So you plant one side leaning into the bottom of the ditch, and when you plant the other side (also leaning into the ditch), your planter shuts off the outside row, and leaves a 60" gap the whole length of the field.

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Both IMU and Dual roll corrections are applied in AOG because AOG knows the tractor’s dimensions (height & width). Last spring I tested a modified version of AOG from @CommonRail that output a roll corrected position that the Teensy converted to lat/long. It worked except I think I had a problem with the Teensy’s lat/long conversion maths, some lose of precision. I have not worked out the fix yet. Maybe we can get his modification into the official AOG, it sounds like your scenario would benefit from it. Does your planter pull straight in those situations?

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