Revolution Reading GPS Data
benr_mc at cogapp.com
Sun Mar 2 07:42:43 EST 2008
On 1/3/08 22:59, R. Hillen wrote:
> is there anybody who succeeded in reading data from a gps device into a
> revolution application?
> How did you do it? Which device did you use?
I did this a couple of years ago in Rev - it was very straightforward. All
(er, virtually all) GPS devices speak NMEA, which is widely documented on the
web. We worked with a couple of different devices, and the software didn't
notice any difference (apart from anything else, I think pretty much everyone
is using the same chipsets).
We did this on Mac and Windows; the only difficulty was locating Mac drivers.
All the devices we worked with were serial originally with serial-USB chips
bolted on; there seemed to be a couple of different ones of these. The other
way that working on Windows was easier in locating the device automatically -
just iterated through COM1-10; on the Mac I think we had to set the name of
the device in the configuration.
The devices just spend a steady stream of data; in the NMEA format this is
ASCII, line formatted; so I had a handler running on a timer which read data
from the port and buffered it, and then invoked a handler to see whether there
were any completed "sentences" to process.
That handler in turn checked whether the position etc information had changed,
and if so invoked a handler to actually do whatever it was supposed to be.
In theory you can switch the devices into a binary format which should be much
faster - but we didn't seem to need the speed and I never dared try in case I
couldn't get it to switch back!
More information about the Use-livecode