MTK3339 GPS

[RobG 1,892]

Sample code to display GPS fix data from the MTK3339 GPS module (group buy #5.)

 

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updated 6/30

GPS-630.zip

[bluehash 1,581]

sweet!

Does it get a lock fast enough? Also, I'll send you a GPS boosterpack in the mail.

[RobG 1,892]

It takes about 1min-2min indoors (cold start.)

[kff2 22]

Rob -- assuming you did not have bluehash's board, how did you connect the GPS module to a launchpad?

[RobG 1,892]

Soldered 0.05 ribbon cable to GPS module and then to ProtoBoard.

All you really need is Vcc, GND, and TX (to P1.1)

 

 

[RobG 1,892]

Updated code (see first post.)

[RobG 1,892]

Another update (checksum can now be used to validate sentence.)

 

[username 198]

Very impressive work RobG! Was looking at a datasheet for this guy and i'm still trying to figure out how it works.

So the module just keeps spitting out GGA, GSA, GSV, RMC, and VTG Data? You don't have to send any messages to it? Did you first configure it at all with there USB/UART GUI?

[RobG 1,892]

Yes, those 5 sentences are sent by default, no additional configuration is necessary.

I will add couple of configuration examples in few days.

[RobG 1,892]

This is how the GPS logger board looks like.

I realized that I don't have any TSSOP EEPROMs on hand (and I am bit tired,) so I will do the testing in few days.

 

 

 

 

If you don't need to use the battery, you can just cut it off.

 

 

[RobG 1,892]

Finally got my memory chip and finished the logger software (still testing though.)

 

 

Here's how it works.

Code which uses logger is responsible for keeping track of time and write address.

After GPS acquires location, memory address is set and timer is started.

During each timer interrupt, location is parsed, then set using setLatitude(), setLongitude(), setTime(), and setDate().

Then writeTimeStamp() or writeDelta() is called. Each write will increase memory location.

Time stamp is 16 bytes long, delta is 4 bytes.

getAbsLatDelta & getAbsLongDelta can be used to determine if there's movement. If there isn't, delta interval can be increased to preserve memory.

 

One time stamp every minute and delta every 5 seconds will use 3600 bytes per hour.

One time stamp every 5 minutes and delta every 10 seconds will use 1584bytes per hour.

 

Attached logger code is complete, but should not be used as it is still in progress

logger.h

logger.c

[bluehash 1,581]

If I wanted it standalone.. How do I get stuff off it?

[RobG 1,892]

MCU has to be programmed to dump memory content via SPI or UART or to go into hi-Z mode when one of the pins is grounded which will allow direct access to memory.

I have plans to do both of those things in the coming weeks.

[bluehash 1,581]

Added to Store.

[krzyk2 11]

I mentioned this in other data logger thread, wouldn't it be better to add a SD (micro?) card to this better than using a memory chip? If it would store the data directly to the card, (without any FS, just write from the first bit, and add some marker at the end) it wouldn't use much more memory of 2553 and it would definitely by easier to get the data out of it, not to mention the amount of data that could be stored.