waynepiekarski

Good news! I tested the latest nightly build Armbian_5.77.190401_Odroidc2_Debian_stretch_dev_5.0.5.7z, and I was able to get /dev/ttyAML1 to do the loopback test at 115200, and talk to my GPS at 9600 baud. I just needed to add "overlays=uartA" into /boot/armbianEnv.txt and it all worked. Thank you so much @martinayotte for fixing this for me so quickly, I very much appreciate it!

Thanks for the quick fix! I'm waiting for the next build to appear tomorrow and then I'll give it a try.

I just tried the picocom test with a wire jumpered from pin 8 to pin 10, and nothing happened. There were no error messages, so the Linux device is valid, but no characters were being echo'd back. I tried the same test with a USB-FTDI dongle and picocom -b 115200 /dev/ttyUSB0 and this worked ok and I could see my typing being echo'd back.

I had a chance to download the nightly build, wrote it to an SD card, and I can now see a uartA overlay. I added overlays=uartA to /boot/armbianEnv.txt and after rebooting, I can see /dev/ttyAML1. But it doesn't return any data. However, when I connect up a GPS serial device at 9600 baud to pin 10 on the header, labelled as RXD1 (#241), I get nothing. I also tried using pin 8 TXD1 (#240) as well, and nothing. I can connect the same serial device to an RPi3 and it works fine. So perhaps this overlay is connecting to a different pin on the board? Originally I was expecting this to be called uartB, because I thought uartA would be the console? Also, I tried the uartC overlay and it does nothing. It does not create any /dev/ttyAML* device, so perhaps that indicates there is some other problem here too? I don't know much about how to debug these kinds of things, but running dmesg and grepping for AML returns this: [ 0.000000] Kernel command line: root=UUID=8594f23b-1887-4ca2-82a9-7a0203eba0ee rootwait rootfstype=ext4 panic=10 console=ttyAML0,115200 console=tty1 consoleblank=0 loglevel=1 ubootpart=b3770000-01 usb-storage.quirks=0x2537:0x1066:u,0x2537:0x1068:u cgroup_enable=memory swapaccount=1 [ 1.694196] c11084c0.serial: ttyAML1 at MMIO 0xc11084c0 (irq = 10, base_baud = 1500000) is a meson_uart [ 1.694482] c81004c0.serial: ttyAML0 at MMIO 0xc81004c0 (irq = 14, base_baud = 1500000) is a meson_uart [ 1.694517] printk: console [ttyAML0] enabled Thanks, Wayne

I found the build configuration https://github.com/armbian/build/blob/master/config/boards/odroidc2.conf which has "next" in the list of targets, so I guess this part is configured properly? # S905 C2 quad core BOARD_NAME="Odroid C2" BOARDFAMILY="meson64" BOOTCONFIG="odroid-c2_defconfig" # MODULES="bonding" MODULES_NEXT="" # KERNEL_TARGET="default,next,dev" CLI_TARGET="stretch,bionic:next" DESKTOP_TARGET="stretch,bionic:next" # CLI_BETA_TARGET="" DESKTOP_BETA_TARGET="" Do I need to file an issue for the nightlies not being built?

I found there is a nightly build server, so I'll see if something gets generated tonight and test that. Otherwise I'll try rebuilding it myself or decompiling the DTB, although it will take me a while since I'm new to Armbian. Thank you so much for your quick reply and commits fixing this, it is much appreciated!

Thanks for fixing this so quickly! Is there a build server that generates new system images that I can test for you? What is the timeline for these commits to make it into the next release?

I read through the link https://docs.armbian.com/User-Guide_Allwinner_overlays/ and it mentions there is README in /boot/dtb/amlogic/overlay/README.meson-overlays which should contain the list of overlays. However, it doesn't mention anything about a UART: So I had a look in /boot/dtb/amlogic/overlay and there seem to be some overlay files. There appears to only be something for uartC, but I want to enable what I believe should be uartB (/dev/ttyS1). I tried putting overlays=uartB in /boot/armbianEnv.txt but nothing changed, and there is no .dtbo for this so I didn't expect much, but I don't really know what I'm doing here. I also did a grep over the entire /boot directory looking for anything mentioning uart* inside the file, I found a few mentions and tried the following overlay line to see if any of them would make a difference: Nothing happened and all the /dev/ttyS0, ttyS1, etc devices still return "Input/output error" when accessed. From the README file and available .dtbo files, it does not appear there is any way to enable the 2nd UART for /dev/ttyS1. I was expecting this to be enabled by default, but is there a trick to getting this working?

No, I haven't done anything like that. Its an unmodified stock image. Is there a guide on how to set this up or what options are available? I've found older articles that talk about cloning github repos from hardkernel and rebuilding the device tree, but this seemed related to older kernels and overly complicated. Is there a way to query what overlays are currently active and the /dev/* entries they map to?

The serial port speed is not configurable? Is this documented somewhere? Also, this fails even without the stty command. So assuming the port was set to 115200 by default, cat /dev/ttyS1 still fails. So it appears like the port is not enabled properly, rather than a baud rate issue.

Hi everyone, I'm trying to use the serial port on pins 8+10 on an ODroid C2. My understanding is that this maps to /dev/ttyS1 by default, but whenever I try to use this serial port, or any of ttyS0, S1, S2, S3, I get the error "Input/output error". root@odroidc2:~# stty raw -crtscts 9600 < /dev/ttyS1 stty: 'standard input': Input/output error root@odroidc2:~# cat /dev/ttyS1 cat: /dev/ttyS1: Input/output error I have done a lot of searching on this forum and others, and it sounds like this could be something I need to enable in my device tree config, or some kind of overlay, but I'm very new to this and couldn't find anything specific on what to do. I had a look around in the /boot directory but couldn't find anything that might indicate that the UART was disabled. I would have thought this /dev/ttyS1 would be enabled by default, while /dev/ttyS2 is optional since it collides with some GPIO pins. I'm using the latest Armbian_5.75_Odroidc2_Debian_stretch_next_4.19.20 and have also had the same problem with the latest Ubuntu as well. Is there a trick to enabling the default UART included with the ODroid C2? Thanks!