Hi there - long time reader, first time poster. I’ll try to keep this to the point but with as much relevant detail as possible.
- we’ve been working a tracking project for cars/boats/bikes/trucks/etc. and using the Telit EZ10-GPS Module, so basically a GM862-GPS in a little box of electronics that until now i’ve never worried about. Our background is in swdev, so we’ve written our Python, put it on the 862, setup our server to receive the info over GPRS, wired the units into the cars, and everything has been fine. My background in electronics is somewhat limited, and so i’ve been working through all the Sparkfun tutorial sections to hopefully learn what I need to know and make a start on the electronic design.
The EZ10 pre-packaged, plug in unit has been good, but we’re now reaching the limitations of that package and want to design our own circuitry around the GM862 module.
So now we get down to my questions:
The product we wish to produce is to be based around the GM862-GPS. We however need to work on the following points:
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Giving our device a fairly wide input range - given it could run in a number of vehicles i’d ideally like it to take anything from 6v to 36v (and enough to cover spikes, etc. out of that range. I could potentially drop that down to 24v, but preferably not.
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We wish to include a 3-axis accelerometer. My main problem is i’m unsure how to interface it with the 862 - my understanding of how this step works is still a bit hazy. Should I be starting with a digital accelerometer or analog? How do I actually make them communicate? Do they literally connect to specified pins or do I need something else in between? If so, what? This is my biggest problem right now, so if you only answer one question, please pick this one
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We also need to setup a battery with it - i’ve looked at the 2000MAh 3.7v ones that seem to come with IPods - would that be recommended?
The documentation for the GM862 says use LiIon in some places, and LiPo in others - does that mean I can use either? The Telit docs also make mention of having a battery pin I can use - whats the process for that? Obviously I want it to charge the battery when on main feed, use the battery when not, and obviously we need to know the status in the GM862’s Python script.
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We wish to be able to detect the incoming voltage from the power supply (prior to it being filtered) and provide that info to the 862.
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We will need LEDs on the board for power, GSM, GPRS. I’m thinking GSM/GPRS can be a single tri-colour, I assume you can’t just drive things like this off the 862 - what do i need to look for in between?
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We also want to give the user options on additional connections - car alarm, door unlock, smoke detector, etc.
What i’m really looking for in this is some form of direction. I really enjoyed the tutorials section of the SFE website, and have been through the process of playing with the Atmel 168 as explained in there, but I think the biggest problem is still understanding how I then interface things like that with the GM862 - I feel like i’ve got a block of info missing somewhere, so if someone can give me some pointers on where to start at least, or as much information as you’re willing to give, i’d be extremely grateful. I realise as a first project this is somewhat ambitious, but so was developing the software side of things when we started, and now it’s brilliant. Any/all help greatly appreciated.