Pi 3 + Microstack GPS communication - raspberry-pi

Question

I bought a Raspberry Pi 3 Model B, a microstack baseboard and a microstack GPS.
I followed the instructions written in the official documentation but I can't connect to the GPS.
Basically, the GPS led flashes so it means it has find a gps fix, but I can't see any data from the PI.
For example, if I try
cat /dev/ttyAMA0
I get always nothing. I already used raspi-config to disable kernel serial and to enable i2c and spi.
Also if I try
stty -F /dev/ttyAMA0 ispeed 4800 && cat </dev/ttyAMA0"
I get an error.
Anyone has any advice, please?
Or maybe these modules are not compatible with Pi 3?
Thanks a lot!

Answer 1

It's hard telling what has been done, or not done. The 'official' documentation from Microstack provides two methods of setting up the serial port. It then continues with
Automatically Starting gpsd
To automatically start the gps service when the Raspberry Pi® boots, re­configure the GPS
daemon by typing into a terminal
sudo dpkg-­reconfigure gpsd
● Choose <yes> when asked if you want to start gpsd automatically.
● Choose <no> when asked “should gpsd handle attached USB GPS
receivers automatically” .
● When asked which “Device the GPS receiver is attached to” , enter
/dev/ttyAMA0 .
● Accept the defaults for other options.
If you have configured your serial port as per instructions and configured gpsd to automagically start and pick up the device you have just setup, ...then, since the gpsd is handling the device (right?), the device will be busy and the command cat /dev/ttyAMA0 should return cat: /dev/ttyAMA0: Device or resource busy...but, it did not.
Either the serial is not configured as per instructions, or the gpsd is not running and picking up the device, or both.
The goal is not to cat your gps data, but the cat not returning an error indicates something is amiss.
Typically, it's just a typo. But it can be from skipping a step in the process, or mixing instructions from various sources so that the left hand doesn't know what the right hand has done.
Try:
sudo killall gpsd if it returns gpsd: no process found that answers one question.
If it returns with no error, follow it up with cat /dev/ttyAMA0. If it returns nothing, the direction you should look is your serial port configuration.
If sudo dpkg-reconfigure gpsd is not allowing you to reconfigure (I thought it was just me) you can modify the configuration of gpsd by using your favourite editor, e.g. sudo nano /etc/default/gpsd and entering something like:
# Default settings for the gpsd init script and the hotplug wrapper.
# Start the gpsd daemon automatically at boot time
START_DAEMON="true"
# Use USB hotplugging to add new USB devices automatically to the daemon
USBAUTO="false"
# Devices gpsd should collect to at boot time.
# They need to be read/writeable, either by user gpsd or the group dialout.
DEVICES="/dev/ttyAMA0"
# Other options you want to pass to gpsd
GPSD_OPTIONS="-n -G"
You may find the -n and -G useful. Save and restart.

Answer 2

I finally found a solution:
On the Pi 3, there are more steps to use serial, you have to disable the BT.
Edit config file:
sudo nano /boot/config.txt
Add this at the bottom:
dtoverlay=pi3-disable-bt-overlay
Then run this:
sudo systemctl disable hciuart

Answer 3

This article was very usefull for me
http://spellfoundry.com/2016/05/29/configuring-gpio-serial-port-raspbian-jessie-including-pi-3/#comment-67160
and i recommand you to read it
Now on RPI3 the Serial port
ttyAMA0 is used by BlueTooth
ttySO refers to the GPIO
The Alias Serial0 refers to the GPIO both on RPI2 and RPI3.
So :
after a reinstallation of Jessie with a recent version to be sure all is clean
as usual
$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo raspi-config
go to Advanced options : Would you like a login shell to be accessible over serial? response "yes" (not as in the microstack datasheet )
$ sudo apt-­get install python3-­microstacknode
To install the gpsd standard tools
$ sudo apt­-get install gpsd gpsd-­clients python­-gps
edit GPSD by
$ sudo nano /etc/default/gpsd
and put the options :
START_DAEMON="true"
USBAUTO="false"
DEVICES="/dev/serial0"
GPSD_OPTIONS="-n -G"
equally
$ sudo nano /boot/cmdline.txt
remove
console=serial0,115200
and save
$ sudo nano /boot/config.txt
you must have at the end
enable_uart=1
Disable the console by
$ sudo systemctl stop serial-getty#ttyS0.service
$ sudo systemctl disable serial-getty#ttyS0.service
i have equally done $ sudo chmod 775 ../../dev/ttySO ( i dont know if it is really necessary )
and obviously a reboot
and miracle the gps works with
cgps -s
NB: you must have a fix on the GPS ( the red led flashes )
jpherrenknecht