Hey Mark.
I am having the same issues. I cannot get any output on a Raspberry Pi 3 with BerryGPS.
Here is my output:
pi@raspi2:~ $ dmesg | grep tty
[ 0.000000] Kernel command line: 8250.nr_uarts=1 bcm2708_fb.fbwidth=1824 bcm2708_fb.fbheight=984 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3dc00000 vc_mem.mem_size=0x3f000000 dwc_otg.lpm_enable=0 console=tty1 root=PARTUUID=e261b53b-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[ 0.000345] console [tty1] enabled
[ 0.820557] 3f201000.serial: ttyAMA0 at MMIO 0x3f201000 (irq = 87, base_baud = 0) is a PL011 rev2
[ 0.822204] 3f215040.serial: ttyS0 at MMIO 0x0 (irq = 220, base_baud = 31250000) is a 16550
pi@raspi2:~ $ cat /dev/ttyS0
^C
pi@raspi2:~ $ cat /dev/ttyAMA0
pi@raspi2:~ $ cat /dev/ttyS0
^C
pi@raspi2:~ $ cat /dev/serial0
^C
pi@raspi2:~ $ cat /boot/cmdline.txt
dwc_otg.lpm_enable=0 console=tty1 root=PARTUUID=e261b53b-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
pi@raspi2:~ $
I really don’t have an option to disable the on-board Bluetooth to free up ttyAMA0 as suggested in the raspberry forum on this issue.
I am really hoping you can help me out on this.
Cheers mate!