Help with GPS module

Hi.. as one of my first projects to get started with the Arduino i would like to connect to my old GPS receiver. After taking the actual Receiver out of its Box i am somewhat confused - its not what i was expecting. Although i have this 'white box' (labelled 1575R) which should be the GPS receiver module i have this one attached to a board with various interestering parts. One of them is a battery and the two ICs on the board are "SIRF GPS2e /LP-7450" and "SIRF ST Y225831". The white receiver is connected via one wire to the whole stuff. I guess, all in all, that this stuff is 'simply' for saving the position data for faster warm up times and to make the signal 'fit' into the serial port, as the circuitry is directly connected to a 6 wire connection which was fed (via an external max232 connector) into USB.

So after all this (I guess half of the data is either useless or wrong the way i thought it was) i would like to know if someone here has an idea for me of how to connect this thing to the arduino. I know noone of you is omniscient, yet i have the little hope that either someone here had experience with that piece of hardware or that someone might tell me how i could start researching - because i did not want to feed 5V right into the wrong line at the very first experiment with it ;0)

Thanks in advance.

Where did you buy it? Can you give us a link to the product page? Can you post some photos?

the module was in a GPS receiver called: Roadstar RN-202. What i have found so far was http://www.skygps.com.cn/UploadFiles/ZYM-GM22-en.pdf . this seems to be the right module as it 'looks' exactly as the thing i hold in hand.. yet the point is, that the schemata in that pds seems to give some info about the main module itself, but has no word about the circuit surrounding it. Oh, by the way, there is a description of the pins of the module in that PDF, yet it has a 2x3 arrangement there and the pins coming from the board on my thing here is 1x6. I wish i could give you more information, but i dont have more myself... and pictures.. maybe i can get a cam for it later today (its now 1.30am) at work... sometimes i think that i am the only person on this planet with no digital camera anymore ;0)

Yep, that's exceptionally confusing. Let me know when you've got more info.

Alright, i am about to 'discover' now what pin means what... i will keep you informed if you like.. in the end its just a new gps receiver for us all - although i doubt its still made ;0)

Ok, i am Done. Since i have to be at work at about 7am i will now go to bed, but will post a 'instruction' on how to use this strange thing ;0)

Nice one

Alright.. here we go. The GPS Receiver is labelled 1575R and got a SIRF II chipset under its hood. In contrast to the datasheet which is available on the internet (see previous post) the pins arent aligned in a 2x3 matrix but in a row

[1] [2] [3] [4] [5] [6]

Now the thing is that it was 'hard' to know what each pin means.. in the end it was operational with that layout:

Pin 1: +5V Pin 2: GND Pin 5: TX

This thing was tested via the GPS Code from the playground and worked like a charm if you connected Pin 5 to the 1st digital Input of the Arduino. I am not sure what the other pins actually are made for, but from reading the datasheet i guess that at least one of them is used for some sort of startup test. I will try to get that one working as well next weekend.. would be nice to have that one connected to a RGP LED that shows the operationstatus of the chip.

So if I understand it correctly you have taken a standard USB GPS unit and removed the 'guts' of it to connect up to the Arduino? Cool ! :)

right ;0) It was once a roadstar rn-202 yet now its nothing more but a trophy of what i have connected to the arduino ;0). Interestering is just that it works so simple.. and that it was unbelievably fast. I havent used it for like 3 years and the moment i attached it to the arduino, and the arduino to the laptop and went outside it took like only a minute to get a full signal.. that was quite amazing for it having only a sirf II...

That is interesting actually. It might mean that by purchasing an old hand held or USB GPS unit from say eBay, you could hook it up to the Arduino and save some pennies over store bought units.

I think this is a good way to safe a few bucks, but keep in mind that this module is slightly slower and less accurate than most receivers you can purchase today.

What i am thinking about is to try an external antenna like ( http://www.dealextreme.com/details.dx/sku.8859 ) and try to make that one work with the arduino as ‘chipset’… yet that is far beyonf my current capabilities…

What i am thinking about is to try an external antenna .... and try to make that one work with the arduino as 'chipset'.. yet that is far beyonf my current capabilities...

Far beyond the capabilities of an 8 bit microcontroller, too. A GPS has powerful analog, DSP, and digital components in a combination that seems almost magical when you consider there are many available for less than US$100.

-j

oh, really? damn ;0) alright - i wont try that one. back to my approx 100k other ideas ;0)

funny thing : today i bought a bargain bin gps receiver from claas olsen.

its a Haicom HI-406BT usb jobbie.

and it has a semi clear window on top (for the digital compass model 406BT-C)

and thru this clearish window i see a 1575R GPS module :)

now if only i can hook it up to an arduino without having to pull the thing apart XD

oh and i recently found out that the interface/charge socket outputs a TTL signal :slight_smile: so i will be testing if that is true as soon as i can get a 1394 cable to butcher :3

good news :3 the TTL outputs as a RTX line using only the RX and TX wires, fed thru a TTL to rs232 converter to the pc or ppc on a baud of 38400. and it happily flows gps data thru :3

not to get that data read on an arduino and stored as some kind of logger, mebe on an old SD card… :3