The beginnings

Earlier this month I ordered an Arduino Nano from the eBay seller “beauty.2011″ and a Skylab SKM53 from “tommyvdp”, also on eBay. This week I received both packages in the mail, packaging was properly done and the items were new as described. If you are unsure from who to buy an Arduino or GPS module, I’d recommend those two. tommyvdp was also very nice, adding a sketch for reading the Skylab with an Arduino on the sales page. Here’s the original code on scribd, and here’s my own sketch currently, without the LCD parts and edited output.

Some example output:
Latitude : 59.330136 :: Longitude : 18.057404
Latitude : 59.330092 :: Longitude : 18.057339
Latitude : 59.330059 :: Longitude : 18.057275
Latitude : 59.329994 :: Longitude : 18.057146

Arduino and GPS module seperate

Arduino and GPS module seperate

Arduino and GPS on breadboard

Arduino and GPS on breadboard

According to the datasheet for the Skylab SKM53, it’s up to 3 meters accurate, and I found it to be sometimes a lot more accurate when you are in a large space like a field. Inside a standard house it can differ something like 10 to 20 meters. At my university though, it can’t even acquire the location and return 0.0000000, 0.0000000. No surprise to be honest, the building is pretty big with lots of network cables and systems. If I leave the building with the GPS turned on, it almost immediately locates itself, which is pretty neat.

1/10" socket strip with Arduino Nano

1/10" socket strip with Arduino

But that’s not all, as it has to be a pretty compact system while leaving the Arduino reusable I bought a few strips of 1/10″ sockets for on a PCB. I can solder this to some protoboard and easily put it on without soldering it directly. This protoboard is also going to be the place where I hook up the Arduino to the GPS module and some powersupply I still have to think of. Not to forget logging all data to an SD card.

 

The SD part is also going to be interesting, as I would like to have everything stored as plain text, so I can easily read it via a normal computer but most simple libraries write to the card as if it was internal storage. Another module with library does store in plain text I believe, but the module is 20 euro and not so compact. So I’ll figure out how I’m going to do that.

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15 Responses to The beginnings

  1. Eric says:

    Just wanted to let you know that the link to your Arduino sketch for the GPS unit is broken. It would be great to see what you did with the GPS module as I just acquired the same one… Thanks.

  2. Eric says:

    I was wondering if you could remove my comments since I hadn’t noticed that I used my last name and didn’t want this to stay online. Thanks for your understanding.

  3. Mati says:

    Hi, can you power the gps module with 3.3 v? Thanks

    • Andreas says:

      Hello Mati,

      Sorry for the long wait to respond, but yes you can. It´s also the only voltage it accepts according to the datasheet.

      • Mati says:

        Hi Andreas,

        Thank you for the anwer, I got this week the gps and an Arduino Uno. I get Latitude:0 all the time. I see on your pictures that you connected the gps to 5v and also on the sketch I see

        This Sketch will run with the SkyNav SKM53 GPS if…..
        RXD Arduino Pin 3
        TXD Arduino Pin 2
        RST Leave Open ? (Connect to a N/O momentary switch pulled low to reset?)
        NC Leave Open
        GND Ground
        VCC +5

        I don’t want to burn my gps on the first attempt, where I need to connect the vcc pin?

        Thanks and excuse my english :-)

        Mati

  4. mich says:

    I got one of these and could never get it to work, so I got one from a different brand and had no trouble with it. The specification says it is a 5V device, which is a bit strange if your datasheet says it is 3.3 V.

    The file I have is labelled Skynav_skm53_DS_002.pdf, although the device is labelled “Skylab SKM53″ not “Skynav” . That might be my problem… right there, although the device looks identical to your photo.

    This is an awkward device to use with the 2mm not 2.54 mm terminal spacing. It also has no LED, which my other GPS has, so you can tell for sure it at least has power.

    The datasheet also describes the TXD pin as an input and the RXD pin as an output.

    So I may have damaged it, or maybe it was a dud to start with. No way to tell. Anyway my other one works fine.

    • mich says:

      Well I got the skylab module out and had another go with it. I chopped off the dodgy daughterboard and soldered wire directly to the holes in the module, got it to work. There was probably an open or shorted solder connection.

      It seems to respond to the same escape sequences as the Globaltop module, not surprising since they seem to both have the Mediatek 2229 chip.

      Can set the output rate to 2 Hz and the baud rate to 57600. Can also select the PMTCHN output for the channel signal strength information.
      So yeah, it does work.

  5. sap says:

    Hi Andreas,

    I was working with the same gps …it works with the uno but with the nano it returns 0.000000. Do you have any suggestions?

    • Andreas says:

      Hey sap,

      I always had the problem with the Nano that it could take very long before it could locate itself. According to the GPS’ datasheet it should take a maximum of 1 minute to get accurate coordinates but sometimes it could take 3 minutes. Always make sure you aren’t around a lot of metal and/or concrete to help the signal and accuracy for the GPS. Also, make sure you have connected everything on exactly the right pins with the NewSoftSerial function etc. Another thing that could be a problem would be power supply but if that wasn’t good I won’t think you would even get 0.000 back. Good luck!

      • sap says:

        Hi Andreas

        Thanks for your quick reply. So basically I dont change the tx (pin 2)and rx pins (pin 3) on the nano. I saw in some forums that someone had trouble with the arduino mega because the pins in mega are different. Also instead of using tinygps library have you tried getting just the nmea data? I was hoping I could do a real time plot on google earth if I have nmea data and excluding the tinygps library also saves be some memory.
        I was using but that didnt work out. The reason I need more space is that I have a lot of sensors which I am interfacing with the arduino to create a complete sensor package.

  6. Ren says:

    So, does this thing run ok on 3.3v then ?
    It seems it can take both, I’d just like to take the safest route.

    • Andreas says:

      Yes it runs fine on 3.3V. If something takes both it’s usually safer to start with the lower voltage. I have always run mine on 3.3V because it just worked.

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