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By ne0x
#87816
I've been brainstorming this idea for awhile now, and I'd like to get some additional (more knowledgeable than me) opinions.

I recently purchased a Holux GPSlim 240 which works just fine over bluetooth, but I would like to log the data from it in a stand-alone (without a computer/cell phone) way.

It has a mini-usb connection, which is not actually USB. The manual gives the pinout and lists two pins as transmit and receive "CMOS 3.0V Level" and it gives the communication specs 38400,8,N,1. Holux sells a serial to USB adaptor cable, but I don't have that. I also have yet to make a cable to plug this into my serial to USB adaptor; I also wonder if that's even going to work.

Anyway, the short version is: Can I plug my GPS receiver into the OpenLog and have it record the data (NEMA sentences) in a file?

I realize that I'm going to need to reprogram the OpenLog to start logging on power up, instead of waiting for the append command. So, if I'm going to reprogram it what's my best choice? I've looked at the FTDI Basic Breakout - 5V, and I see that I'd have to make an adaptor cable to swap the tx/rx pins before connecting the OpenLog. Is this the tool I'll need to upload new code to the OpenLog? Can I also use it as a serial to USB interface, for instance to communicate with the OpenLog? What about the GPS?

I haven't given much thought to the power source yet, batteries of some kind naturally. LiPo would be nice, if I can afford it and work out the charging circuit.

OK, more crazy ideas...
Can I use the Breakout Board for FT232RQ USB to Serial to make an adaptor cable for the GPS?

What about tapping into the microSD card with a card reader so that this whole device can just plug into a USB port to get at the files once it's done logging? The USB port could provide power for the possible battery charger.

Alright, I guess that's just about enough crazy for now; sorry to overwhelm, but I really want to know what some other people think about this project.
Last edited by ne0x on Tue Dec 29, 2009 10:12 am, edited 1 time in total.
By ne0x
#88211
OK. So I've done some more poking around, and I've realized that there is already something that meets most of my needs: the Logomatic Serial Datalogger.

So, my new plan is to get that, wire in the input from my GPS, and hope for the best.

I'd still like to be sure that I've got everything I need in one order.
  • - Logomatic
    - 860 mAh LiPo
    - microSD card
    - SF project case
    - 4-40 screws
    - external power switch
    - mini-USB cable to cut up, or USB socket
    - female end for the cable
    - angle headers
By teekay_tk
#88316
seems like fun, but why not buy a standard gps datalogger for about £50 of ebay. Yes, it wont be as much fun, but it will be cheaper
By ne0x
#88322
Yeah, not as much fun; and I'd like a useful project as an introduction to this stuff. Also, I'm hoping to get this on Free Day.