How can a BasicStamp2 download waypoints into Garmin eTrex GPS?

hyeatman

Hello Everyone!!

I'm new to the Parallax form. I am working on my son's class project where we are building an electric power model boat that is beig guided by GPS to navigate around a small lake. I am using the BasicStamp 2 to parse the informatin from my handheld Garmin eTrex "Venture" GPS unit. I am working with the $GPRMB data to help steer the boat using a RC servo. My question is can I have the BasicStamp download to the GPS unit my specific WayPoints that I want the boat to navigate to. I have seen several article on reading GPS data with a Stamp but nothing about being able to communicate data back to the GPS unit. I want to be able to originate and store my WayPoints in the BasicStamp and them download them into the GPS unit. Any suggestions or ideas would be helpful. I have read several articles by Jon Williams and they are most helpful. Thanks for your help.

Hoyt Yeatman

Lee Harker

Hoyt,
Just curious, what part of the class project does your son get to work on?

Lee

hyeatman

Dear Lee:

In truth I am doing most of the planning and programming for the project but we all pitch in when it comes to undestanding the concepts and building the model and other systems.

Thanks,

Hoyt

Jon Williams

You can find the protocol on the Garmin site ... though I think it would be difficult (if not impossible) to implement on a micro as small as the BASIC Stamp.

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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA

Larry

You might want to rethink your waypoint storage scheme. The Etrex will store many more waypoints than a Stamp will. also, the interface is better. You can enter waypoints directly to the Etrex, and if you want to do it from a file, there are several freeware utilities that will handle that for you. GPS Utility is one.

http://www.gpsu.co.uk/

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hyeatman

Thank you for your thoughts. My reason and desire to have the waypoints stored and controlled by the stamp is to allow the navigation system to have its waypoints updated remotely thus allowing the path of the boat to be altered even though the boat is underway. My hopes were to use the “smarts” of the eTrex to do most of the math in terms of figuring out the correct headings for each waypoint. Perhaps I need to look at the possibilities of doing these calculations within the stamp. I have been most impressed with Jon Williams work and I am wondering what approach he might use to accomplish this task.

allanlane5

The BS2 itself has very limited storage -- 26 Bytes of RAM and 2K of EEPROM. You can easily add 8-pin EEPROM's to it, though, and store your way-points in there for later download from the BS2 to the GPS unit.

hyeatman

Thank you for your suggestions. Taking the advice that a micro as small as the BASIC Stamp will not allow me to download Waypoint updates into the eTrex, what software approach should I take? Perhaps using the eTrex as “only” a GPS Position and true Heading device and attempting to calculate the proper bearing correction for steering a RC boat to a specific Waypoint would have to be done by the Stamp itself. Any thoughts on how difficult the code would be for such implementation


Hoyt

achilles03

hyeatman,
I think you're approaching this problem from the wrong side.· Why do you need the eTrex to store the waypoints?· Whether the eTrex or the BS2 figures out which way to go in order to reach a waypoint doesn't make a difference.·

You can get the BS2 to determine which way it needs to·"steer" based on the current location, provided by the eTrex, and the next waypoint, provided by you (whether remotely or hardcoded).· All you need is a little trig coded into the BS2.· This can be as almost as accurate as the eTrex's method of bearing determination.· The main thing you need to hardcode into the BS2 is the meters/deg latitude and meters/deg longitude (ratio).

Hope that helps,
Dave