A few MapThis / GPS questions
Hi all... I'm new to the forum although I've been lurking for a few weeks now. I've just purchased a GPSlim 236 and am awaiting it's arrival in the mail but in the mean-time, I've got a few general questions about Deniska's fantastic app and the PSP and GPS in general.
I'm keen to try a few hardware options out. I'm no electronics guru but I've scratch-built a few devices over the years. However I have a fairly limited knowledge of the PSP hardware and also the limitations of homebrew on the PSP. That's where I was hoping I could get some help. I suppose most of these questions are directed at Deniska but if anyone can provide input, I'd be most appreciative.
1. Bluetooth: From reading around other threads in the forum, I can see there are a few barriers to this. Firstly, I understand we're fairly limited as to what we can ask from the PSP in terms of power to run any devices from the remote socket. Does anybody know if similar limitations apply to the USB socket?
I also understand that the GPSlim 236 and, by the sounds of it, most other PDA GPS systems transmit their data as serial (NMEA 0183). If a RS232 - USB converter were to be used, could the GPS be run from the USB port (assuming there were any advantages to doing this)?
I know there are off-the-shelf bluetooth tranceivers which can output serial data. Something like this: http://www.rfsolutions.co.uk/acatalo...Matik_2.0.html
The handy thing with a unit like this is that it can be a Master device independantly and can be wedded with the GPS (using an additional programming board whos price I'm having a suspiciously difficult time finding) so that it automatically connects as soon as the two devices are running. This means that the PSP doesn't need to know anything about Bluetooth as it's all handled by the Transceiver module.
According to the spec sheet, this will run off a 3.2v - 5.1v regulated supply (is the output from the remote socket regulated?) with a max current draw of less than 100mA (average under normal operating would be closer to 20mA - 30mA) so I assume this could run off the power lines on the remote connector. Even if this is still too much drain, it could have it's own power supply if necessary. It also provides for output as serial data with an adjustable baud between 1200 - 2765800.
It's a little pricey (the modules I can see range from £65 - £95) and needs to be configured on an additional programming board first but from what i can see, this should allow the PSP to communicate with the GPS via Bluetooth. I'm considering giving this a bash as a proof of concept, if nothing else, assuming I can get the necessary info to show it could work.
A cheaper option would be to just use a Bluetooth receiver and write software for it to handle all the Bluetooth functionality on the PSP. Is this even possible?
Comments?
2. General GPS question. I don't own a GPS yet so I don't know exactly what your typical unit is capable of. I assume that if I buy Tom Tom 5 or whatever in-car system, that I would be able to get point to point directions on the fly, right? So if I'm driving in my car in the middle of nowhere, I would expect to somehow be able to enter an address and have the unit calculate a route from here to there. Can GPS systems normally do this?
If so, then how do they manage it? With my limited imagination, I can picture a system whereby the maps would need to have all of the information about roads, one-way streets, addresses for everything, post-codes etc. I would assume this would result in very large map files. Given that a lot of PDAs don't have very large hard drives, how do they get around the problem of large map areas?
I always figured that if I bought an in-car GPS, that I could drive anywhere in the UK and get street directions the whole way. Is this not the case?
I'm just wondering because, of all the features which could be implemented in MapThis, on-the-fly directions would be by far the most useful, although it seems, in my head anyway, to be extremely difficult, if not impossible to implement on the PSP platform.
As a means of fudging this ability, could WiFi be used along with some of the code from in7ane's great map downloader to query google/msn while the system is running to download the POIs for a set of directions?
4. Are there any GPS units like the GPSlim which can act as network devices and transmit their data via WiFi (at a glance, Google seems to suggest there are)? I assume, since the idea is conceptually so simple, that someone has already thought of this. I'm just wondering what the barriers to an option like this are? I'm guessing the PSP can't be set-up as a router so you'd need a GPS with a built-in router which sounds like an unlikely device.
Sorry for the long post but I would like to add something to this project if it's at all possible and since Deniska seems well-and-truly on-top of the coding side of things, I wouldn't mind experimenting with the hardware.
