RPi3: GPS cannot connect via UART

[ghost]

1. Stratux version: 0.8r2 build da5f5d003d

2. Stratux config:

   SDR [X] single [ ] dual

   GPS [X] yes [ ] no type: MTK3339

   AHRS [ ] yes [x] no

3. Description of your issue:

On the Raspberry Pi 3, devices ttyAMA0 and ttyS0 are not the same device. ttyAMA0 connects to the PL011 hardware UART (accessible via GPIO pins 8 and 10). ttyS0 uses a differrent hardware address and interrupt (mini-UART / Bluetooth?) -- in either case it does not address hardware connected to pins 8/10.

Suggest removing references to /dev/ttyS0 from ry835ai.go.

root@raspberrypi:/dev# dmesg | grep "tty"
...
[    0.268390] 3f215040.uart: ttyS0 at MMIO 0x3f215040 (irq = 29, base_baud = 50000000) is a 16550
[    0.927135] 3f201000.uart: ttyAMA0 at MMIO 0x3f201000 (irq = 83, base_baud = 0) is a PL011 rev2

root@raspberrypi:/dev# cat /dev/ttyAMA0
$GPGSV,3,2,12,51,36,199,,17,33,091,27,25,18,317,25,24,18,247,26*76
$GPGSV,3,3,12,03,09,034,14,05,05,187,16,28,03,147,16,23,01,068,*79
...

root@raspberrypi:/dev# cat /dev/ttyAMA0
root@raspberrypi:/dev# 

[peepsnet]

So can we get the 835/836 to connect on the pi3?

I am having an issue with that. I can get ttyS0 to show data with the 835 connected to pins 8 & 10. But it is unreadable. I am not able to get any baud rates to return usuable data...

If I screen /dev/ttyS0 9600 I see data but it's junk. If I disconnect pins 8 or 10 the data stops...

I have tried to connect on /dev/ttyAMA0 on my rpi3 and nothing. I have talked with cyoung about this.

I have 2 835's and both work on my rpi2. Plugging either 835 in to the rpi3 and I get nothing usuable.

My Rpi2 does not have a ttyS0 at all. Does yours? With the 835 connected there is a ttyAMA0 but no ttyS0

The ttyS0 only was seen on the rpi3...

PS. Got 2 ry836ai on the way

[skypuppy]

http://www.briandorey.com/post/Raspberry-Pi-3-UART-Boot-Overlay-Part-Two

[ghost]

Add dtoverlay=pi3-miniuart-bt to the end of /boot/config.txt. This will release the Bluetooth adapter from using the hardware UART, and make serial accessible over the GPIO pins.

[ghost]

Simulpost! :-D

[skypuppy]

Great minds think alike: always in the gutter.

[peepsnet]

I followed the steps here: http://www.briandorey.com/post/Raspberry-Pi-3-UART-Overlay-Workaround

and was able to get valid NMEA data on ttyAMA0

Does this mean we have to have version checks for RPi3's and mod the /boot/cmdline.txt , /boot/config.txt and sudo nano /lib/systemd/system/hciuart.service on all RPi3 on initial boot?? or can we do this for all RPi's and it will still work??

And then the Bluetooth will never work with a serial port interface in use????

[ghost]

@peepsnet -- we're using a version of Jessie dated after 3/18, so the simplified method in @skypuppy 's post (and originally discussed on reddit: https://redd.it/4bh5ku) is what we've been using on our Pi3s, and what I submitted in PR #394.

In theory, this should still allow BT use on the "mini UART" - though I haven't tested. Also need to validate on older Pi's.

[peepsnet]

Thats just the nano /boot/config.txt add dtoverlay=pi3-miniuart-bt reboot ok. ill try that.

[peepsnet]

SO the question become does this line in the /boot/config.txt break the RPi2s and RPi0s...