Re: [gpsd-dev] How to access two identical USB GPS plugged into one Raspeberry pi ?

[Joshua Judson Rosen]

On 6/18/19 12:04 PM, Sanjeev Gupta wrote:
> Hi,
>
> Please try the line
>
> DEVICES="/dev/ttyACM0   /dev/ttyACM1"


Also: since it sounds like you probably need to be able to reliably
identify which device is which...:

You might find the aliases in /dev/serial/by-id to be more useful,
(IIRC there are provisions for USB representing device serial-numbers in those 
device-names,
 but plenty of USB devices don't actually implement unique serial numbers...).

Alternately, if your devices don't have unique serial-numbers,
you may find the aliases in /dev/serial/by-path more useful.


> On Tue, Jun 18, 2019 at 9:36 PM Benoit Lechardoy <address@hidden 
> <mailto:address@hidden>> wrote:
>
>     I have two identical devices plugged in : they are seen as :
>     /dev/ttyACM0
>     /dev/ttyACM1
>
>     I would like to access both via GPSD to log positions and make statistics 
> about precision of both modules (antennas are set very close).
>
>      From now, I know that those two modules communicate with the Pi :
>     sudo cat ttyACM0 | grep -m 1 "GPGLL" return a NMEA position
>     sudo cat ttyACM0 | grep -m 1 "GPGLL" return a NMEA position
>
>     GPSD can only read the second one (ttyACM1) and I don't know how to 
> configure it to access both, ideally via Python.
>
>     /etc/default/gpsd configuration :
>
>     START_DAEMON="true"
>     USBAUTO="false"
>     DEVICES="/dev/ttyACM0"
>     DEVICES="/dev/ttyACM1"
>     GPSD_OPTIONS="-n"
>     GPSD_SOCKET="/var/run/gpsd.sock"