![]() I didn’t have my serial adapter with me, so I couldn’t double check the serial NMEA output, but I will do that. But even more definitively, when I overrode the coordinates going on the can bus with a special can filter I’m playing with, when switching on and off the TCM, the line didn’t move at all. I parked on a snow drift and toggled the TCM on and off and the coordinates definitely moved consistently and the distance from my line shifted consistently. Tonight I verified that, in fact, the starfire receiver does integrate the roll (and almost certainly the offsets) into coordinates it sends over the can bus, and also the coordinates displayed on the info screen. Wish I could edit my other post and cross it all out… I’m definitely wrong. Later on I may try to see if I can find the messages for the steering angle sensor. But if I left the deere stuff in place and just modified the data, I believe AOG could drive the tractor. John Deere’s messages aren’t encrypted, but they do try to verify that the modules are all Deere approved. Unrelated, but down the road I’m convinced it’s entirely possible to drive the John Deere steering valve over the bus. ![]() And that I haven’t been able to observe any changes to the GPS position data when I disable the TCM (which I plan to test again soon). However the fact that I’ve always gotten really wavy data out of the serial NMEA stream on my 4wd tractor, and that I’ve verified the same positions are going on the bus as the NMEA cast doubt on that. I guess you could park on a hill, turn TCM on and off and see how the NMEA data stream is affected.īut I did initially suspect that the GPS data was compensated in the receiver, at least to the NAV computer. And I also know that the TCM data is being transmitted on the bus, because when I hook up a 3000 unit I have with a bad TCM, I can see the bad data on the bus (it’s all 0xff’s) and the tractor won’t steer, no matter if you tell the receiver to turn off the TCM or not. All I know is the GPS information going to the navigation system (I altered the longitude data to move the tractor over a couple of feet and it works so the nav system is using that data) is the same as the position data in the NMEA output stream. I don’t know either! I will do more investigations, though, as this stuff that I’m already looking into for another project unrelated to AOG. ![]() If I park on a tippy spot, I should see several differences between the position with TCM on and off. I proved that a long time ago with AOG’s calculated heading (it was ver wavy due to the tractor rolling back and forth).Īgain I’ll test it again. I’ll have to double check things, but so far this is what my tests reveal…Ĭertainly the RS232 NMEA output is not corrected for roll. Now it could be that SF1 accuracy doesn’t have enough precision to show me a change in altitude of 2 meters and the other offsets aren’t that big. ![]() Disabling or enabling the TCM did nothing to the latitude, longitude, and altitude numbers. I came to this conclusion by observing the position data on RS232, on the Starfire info page on my GS monitor, and by observing the can bus messages coming from it. They do have a TCM module that measures roll and keeps track of fore/aft position and height, but as near as I can tell that data is passed over the can bus to the navigation computer (is that in the monitor or separate like Case?), which does the integration in there. As it happens I’ve been looking at my StarFire receiver lately and from what I can tell, the Starfire receivers do no roll compensation at all.
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