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If anyone wants information on getting RS232 GPS out of a GreenStar receiver, I can tell you how. Deere sells a $300 cable to do it, but it's not hard to splice into some wires up on the receiver and just use a cheap serial cable. And on the new GreenStar receivers, you can actually get serial from the back of the monitor I've been told.
 

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So I couldn't get things to work quite right with my GreenStar receiver today. I configured it for 5 Hz update, 38400 baud, and for my other section controller I have GGA and VTG turned on. Looks like from the code you are using GGA and RMC. I turned that on too, and I can get proper data (both windows and Linux), but it's not working quite right. It takes it a couple of seconds to detect speed, and then as I drive around the yard the coverage doesn't mark like it should. In fact I can turn in a big circle and it ends up being at most a U shape on the screen. And when I stop moving, the speed remains about where it was and never goes to zero. Any ideas what is going on?
 

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I have an old Trimble ez guide I'd like to rig for auto steer but I don't want to spend a bunch of money. Terrain compensation would be a plus but Mostly want it to steer me in a straight ab line and nothing more. My light bar has been updated as much as it can. Any thoughts.
 

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Discussion Starter #44 (Edited)
So I couldn't get things to work quite right with my GreenStar receiver today. I configured it for 5 Hz update, 38400 baud, and for my other section controller I have GGA and VTG turned on. Looks like from the code you are using GGA and RMC. I turned that on too, and I can get proper data (both windows and Linux), but it's not working quite right. It takes it a couple of seconds to detect speed, and then as I drive around the yard the coverage doesn't mark like it should. In fact I can turn in a big circle and it ends up being at most a U shape on the screen. And when I stop moving, the speed remains about where it was and never goes to zero. Any ideas what is going on?
Yes, too much data going in. Try it with RMC at 5 hz and everything else off. The serial port, and it can be changed to read faster is limited to about 8 or so reads per second. It needs the latitude and longitude from RMC and i think it keeps getting dropped. Speed also is just a direct read from RMC.

GGA is only used for elevation - which isn't used anyway. I probably should change it over to needing only GGA as that seems the most common. Thoughts?

Need to fix the serial port. Its a Microsoft Gem of misery in C#.

The speed not updating is an undocumented feature. the fix position has to move at least 0.5 meters before it will update the new position. this prevents drawing a million triangles while the GPS boffles around while you are standing still or going really really slow. I know i need to look at how that works. So there has to be a balance between recording enough positions while slow and way too many while really slow or stopped. I shall noodle on that. So good to have more eyes look at alpha version software.
 

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Discussion Starter #45
I have an old Trimble ez guide I'd like to rig for auto steer but I don't want to spend a bunch of money. Terrain compensation would be a plus but Mostly want it to steer me in a straight ab line and nothing more. My light bar has been updated as much as it can. Any thoughts.
I have one of those too, not the most accurate. You swear your driving in a straight line but the light bar keeps telling you strange things. They are quite drifty and can vary quite a bit per pass.

But they do work for AOG. Set the serial port to RMC at 5 HZ and 19,200 baud and hook up the usb to serial cable and voila, you have mapping and a light bar.
 

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Do you mean you should change your code to only require RMC? RMC has the speed and heading. I think it would be nice if your code could handle a data stream at 5 Hz with multiple message types enabled, even ones you don't need or care about. There's no reason the computer can't handle it if you can figure out how to make C# do it.

The Raven Smartboom uses GGA and VTG. From what I can read, VTG is similar to RMC, except that it uses metric for speed instead of knots. I dunno.

I'll give it another test tomorrow with just GGA and RMC on.
 

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Discussion Starter #47
No, the code uses RMC. Its is all it needs to map and work. Its not too hard to switch off a few sentences in the JD setup. But yes, would be nice if it could read faster.

I'm not sure where the speed limitation is. I'm using readLine() for reads of the port which waits for an entire line to be read before dumping it into a single message and then hand it off to the NMEA parser to determine if its a real sentence, what type of sentence like GGA RMC, do a complete checksum to make sure its valid, parse it, then store each item, or discard the line if its garbage or something other then GGA or RMC . That way i don't need to search a string and put together all the pieces on top of it all too.
 

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Was just checking to see what x86 single-board computers I could find that could run Linux (wine requires x86) or Windows and found this one that will be available soonish:
UDOO X86 - UDOO

Looks very appealing for this application because it has built-in arduino-compatible circuitry for doing I/O. I assume it's a dedicated Atmel processor that you can talk to from the main OS somehow. Combine this with a touch screen in a little case and you'd have a nice unit.

Of course LattePanda is another good choice. It also has en embedded Atmel processor for doing I/O.

Time to add a 3d printer and CNC milling machine to my list of winter projects. Ha. I will never get anything done at this rate.
 

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What would be a suitable GPS receiver that isn't complete rubbish? Are you doing testing with a standalone receiver or just streaming nmea out of an ezy guide or starfire?
Thanks
 

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Discussion Starter #51
What would be a suitable GPS receiver that isn't complete rubbish? Are you doing testing with a standalone receiver or just streaming nmea out of an ezy guide or starfire?
Thanks
I have used a 40$ Garmin USB receiver, the ez, and S3 Outback, and an S2 with full RTK (what we seed with). Pretty easy to guess which was best!

Haven't looked a lot at receivers but this one i'm sure is very good.

SMART6? Smart Antenna | High-Precision GPS Devices | High-Precision GNSS Devices | Products | NovAtel

or better

SMART6-L? Smart Antenna | High-Precision GPS Devices | High-Precision GNSS Devices | Products | NovAtel

or bestest

RELAY? RTK Radio | RTK Radio Relay | High-Precision GPS Devices | High-Precision GNSS Devices | Products | NovAtel

But how accurate do you want to be? How much you want to spend? Answer those two and where they compromise enough and meet is what you buy.
 

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I'm hopeful that one of the low-cost RTK units being developed for UAVs will be good for farm use some day soon. A receiver that can do RTK and just output standard serial data would be idea. I think the Reach RTK system is close to what I want. But I've heard about another system on DIY drones but I can't remember what it's called. Apparently it uses standard Ublox GPS receivers.

EDIT: I think this was it: https://www.indiegogo.com/projects/the-world-smallest-precision-gps#/ -- Watching this with interest. If harvest ever ends and there's money available I might buy a pair of their units.
 

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A) accuracy - all I need is something around 30cm or so. Good enough for spreading or spraying.

B) budget - I'm trying to do it for under $1500 for hardware and software. Including a 10" android tablet of some kind and suitable mounting hardware. Even tho I already have an iPad, I'm happy for fork out for a Samsung or something similar for using on the farm because there are a few apps that are only for android which is frustrating.

I'm really tempted to order a drotek tiny Rtk setup, it seems like a really good option to get cheap accuracy. The only thing that has me is the data radio modem for the rtk signal. No one seems to be making recommendations on what works well and what doesn't (or I'm just not searching for the right things)

I'm sure with a bit of work with a weatherproof enclosure I could make it up with an internal rechargeable battery for the base (so it could basically be set up on a fence post for the days work).

A novatel would be great but I think it would blow my budget into oblivion.

Back on topic, have you ever seen a boom model that rinex used in their as7500 boom auto section controller? I set a few up when working for GPS ag and they were more comprehensive than the raven smartboom (I think it was?). They measured everything and did turn compensation as well i think. Might be worth a look.

Cheers
 

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The AS7500 does look good. If I'd known about it I wouldn't have bought the Raven unit, though I got a really good sale price on the SmartBoom.
 

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Discussion Starter #55
Several updates. Step 2 of xx was to get actual relay control. Working pretty good. v1.2 will be up on Github soon including Arduino ino project.

So, total cost, a 200$ tablet, a 22$ USB to RS232 cable, a 25$ Arduino Uno, a 15$ 8 channel relay board, few hookup wires.

* Fixed the RMC and GGA parsing routine, rather then reading an NMEA line and then updating, read all existing lines and process all at once.
- much faster accumulation of data
* Changed OpenGL draw routine from being triggered when RMC rec'd to 5 frames per second and triggering functions from there.
- three seperate threads - GPS Serial IO and decoding NMEA stream, sectionRelay serial IO, Draw routine.
* Ability to save and retrieve fields
* Changed the Section tab to remove clutter with less sections
* added section on and off request in section control. Allows the section to delay turning off and when turned on to remain on for 2 secs minimum.
* Fixed fonts consistency
* Added bottom status bar - looks way better in Linux
* Added Arduino serial port to control sectionRelays
* Output the section on off status to Arduino for full external control of sections
* Added port selection to choose port for sectionRelays.
* added hitched or rigid in vehicle
* added antenna height in vehicle
* added port status in status bar
* added distance reset in status bar
* fixed section drawing so it uses section position rather then fix position to end section drawing
* added a guidance page to set overlap
* fixed bug in section control loosing accuracy from converting double to int too soon. (missing a pixel or two)
* other miscellaneous changes

A little video. As usual click on the YouTube and watch in there is higher resolution

 

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Wow! That's a lot of progress! I'll give it a test here as soon as I can. We had a run of good weather these last days so we're finishing up the last of our seed alfalfa.

What tablet are you using?
 

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charging while using with tablet? can you run a USB splitter, then run 1 into RS232 and one into charge facility?

Ant....
 

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Discussion Starter #58 (Edited)
Wow! That's a lot of progress! I'll give it a test here as soon as I can. We had a run of good weather these last days so we're finishing up the last of our seed alfalfa.

What tablet are you using?
It keeps, either raining or snowing or cold and cloudy. Harvest isn't happening, so a bit more time to play lol.

Just a Lenovo tab2 yoga 10"

Awesome if you could test it.
 

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Discussion Starter #59
charging while using with tablet? can you run a USB splitter, then run 1 into RS232 and one into charge facility?

Ant....
some work, most don't. The problem is you're connecting to a USB device and providing power to it. So how do you charge something that is supplying power is the problem.
 

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Dont qoute me but some tabs can do this but i believe the ipad cannot and was mentioned by apple...ill look into it..

Ant...
 
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