Serial gps (/dev/ttyS0)

[Colin Larsen]

Hi all

I'm beating my head against a wall a little here trying to use a serial gps.

Connected to the Pi3 uart pins (14/15)

Enabled serial in raspi-config

Disabled the console in ....../cmdline.txt

Have a serial device /dev/ttyS0

Modified /etc/default/gpsd

# Devices gpsd should collect to at boot time.
# They need to be read/writeable, either by user gpsd or the group dialout.


DEVICES="/dev/ttyS0"


# Icom705
#DEVICES="/dev/ttyACM1"

# DigiPi Hat
#DEVICES="/dev/ttyUSB1"

# Generic GPS Dongle
#DEVICES="/dev/ttyACM0"

# Other options you want to pass to gpsd
GPSD_OPTIONS="-n -b"

# Automatically hot add/remove USB GPS devices via gpsdctl
USBAUTO="false"

dmesg grep | tty shows the following -

[    0.000440] printk: console [tty0] enabled
[    3.286883] 3f201000.serial: ttyAMA1 at MMIO 0x3f201000 (irq = 114, base_baud = 0) is a PL011 rev2
[    3.287084] serial serial0: tty port ttyAMA1 registered
[    3.288634] 3f215040.serial: ttyS0 at MMIO 0x3f215040 (irq = 86, base_baud = 50000000) is a 16550
[    3.289015] printk: console [ttyS0] enabled
[    7.619023] systemd[1]: Created slice system-serial\x2dgetty.slice - Slice /system/serial-getty.
[    7.625516] systemd[1]: Expecting device dev-ttyS0.device - /dev/ttyS0...
[   14.048623] pps pps0: source "/dev/ttyS0" added

Cat /dev/ttyS0 is not what I expect to see. Initially it was standard gps messages but now looks like the wrong baud rate is selected ??????

Nothing from cgps but I do have a pps signal/3d fix light on the gps unit

Any thoughts on where to look or what I missed??

Cheers, Colin, ZL2FL

[Colin Larsen]

I had an email from a member asking me if I had added a couple of other lines into the boot.txt

enable_uart=1

init_uart_baud=9600  (or whatever baud rate your gps device outputs)

In the meantime I'd done a rebuild of the Digipi - but I added those anyway. Although the initialize page does not show the gps as available I added ttyS0 to the appropriate field and it worked!

Many thanks for the help!

[Craig]

great work guys!

digipi only looks for ttyUSB* and ttyACM* when suggesting device files, I'll add ttyS* as another hint.

-craig
KM6LYW

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