Talking to a GPS unit over USB

[Dar Scott]

On Saturday, April 10, 2004, at 05:51 PM, Trevor DeVore wrote:

>> I would expect that a GPS unit with a USB interface is set up to look 
>> just like serial.  If that is not the case, you will not be able to 
>> establish communications without something special.

> Rats, it looks like it isn't going to work .  driverNames() returns 
> empty.  There is a serial connection cable that I can get for it.  I 
> have a Keyspan serial->USB converter so I think I will pick that up 
> and give it a try.

Rats.  I am surprised; the GPS protocols are based on a family of 
navigation standards that specifies serial.

Here is an alternative to driverNames() that might come up with a 
different answer.  (I only know of driverNames() missing the built-in 
modem; if you see anything else in deviceNames() and not in 
driverNames(), please let me know.)

-- Ken Ray and Dar Scott did this
function deviceNames
   local theNames="", ioregOutput, skipLines, temp
   local IOTTYDevice, IODialinDevice, IOCalloutDevice
   set the hideConsoleWindows to true
   put shell("ioreg -n IOSerialBSDClient") into ioregOutput
   repeat forever
     put lineOffset("IOSerialBSDCLient",ioregOutput) into skipLines
     if skipLines is zero then return thenames
     delete line 1 to skipLines of ioregOutput
     -- Get all the data between the braces
     put char(offset("{",ioregOutput)) to (offset("}",ioregOutput)) of 
ioregOutput into temp
     get matchText(temp,"\"IOTTYDevice\" = \"(.*?)\"",IOTTYDevice)
     if it is not true then next repeat
     get matchText(temp,"\"IODialinDevice\" = \"(.*?)\"",IODialinDevice)
     if it is not true then next repeat
     get matchText(temp,"\"IOCalloutDevice\" = 
\"(.*?)\"",IOCalloutDevice)
     if it is not true then next repeat
     put IOTTYDevice,IODialinDevice,IOCalloutDevice & lineFeed after 
theNames
   end repeat
end deviceNames

Another clue that you can open it as serial is finding it with 'ls 
/dev/cu.*'.

I think there are three categories of serial devices in OS X and I 
suspect that driverNames() only looks in one.

Dar Scott