On Sun, Dec 11, 2016 at 09:56:15PM -0700, Gregory Nowak wrote:
>Can anyone out there with a raspberry pi 3 and a pl2303 cable please confirm
>that the devuan_jessie_1.0.0-beta2_arm64_raspi3.img.xz image actually
>has a working serial console? I do see that cmdline.txt in the first
>fat partition defines ttyAMA0, so it should work, but doesn't seem to
>work for me. I can tell that the rpi3 boots, because if I plug an
>ethernet cable into it, I can see it request an ip address from my
>dhcp server. Also, if I just unplug the power cable from the rpi3 when
>it is still running, and put my sd card into a reader, the file system
>on the second partition is not cleanly unmounted.
>
>I'll describe what I'm doing, in case the problem is mine.
>
>1. I have a pl2303 cable, which I asked a sighted person to label for
>me with pieces of tape, so I know which color is which. I have used
>this same cable on my rpi2 some time ago to get a serial console, so I
>know the cable works, and is labeled for me correctly.
>
>2. As far as I've been able to determine, the GPIO layout between the
>rpi2, and rpi3 is the same. With the rpi3 board positioned with the
>usb hub to my right, and the sd slot to my left, the first row of pins
>on the top going from left to right would therefore be pins 2, 4, 6,
>8, 10 ... So, I plug the black wire from my pl2303 cable into pin 6,
>the white wire into pin 8, and the green wire into pin 10. On my pc, I
>launch a screen session as:
>
>screen /dev/ttyUSB0 115200
>
>Yes, the pl2303 cable shows up as ttyUSB0 on my pc. Then I plug in my
>power supply ... and nothing happens, even though I can tell the rpi3
>does boot as I mentioned above. When I did these same steps on my rpi2
>multiple times, I would get with in a couple of seconds after
>connecting my power supply "uncompressing linux ..."
>
>Doing some research, I found this:
>
><https://openenergymonitor.org/emon/node/12311>
>
>So, as the instructions there suggest, I added to config.txt:
>
>dtoverlay=pi3-disable-bt
>
>but no joy there either. Before doing that, I also did try changing
>ttyAMA0 to ttyS0 in cmdline.txt, but that didn't do it for me
>either. I am wondering if the bluetooth taking over ttyAMA0 also means
>that the serial pins on the GPIO have changed between the rpi2 and
>rpi3, but haven't been able to find this out in my research. My
>research comes up with pictures for the rpi3 GPIO layout, but no
>textual description of the physical pin numbers as I was able to find
>when I first started with the rpi2.
>
>If someone out there could verify the rpi3 beta2 image has a working
>serial console, that would be great. If from what I described someone
>can determine that the problem is mine, then please set me
>straight. I'll do my best to provide whatever other info may be
>needed. Thanks.

Hello Greg,

First of all, this might help you with the GPIO stuff:
https://pinout.xyz/pinout/uart


Now, on to the serial port.

According to <http://frederickvandenbosch.be/?p=1672>:

> It seems the recently launched Raspberry Pi 3 behaves differently with
> regards to the UART interface on the GPIO header.

You might need to make sure that /boot/config.txt has the following line:

    enable_uart=1

(perhaps add `force_turbo=1` as well)

More information here:
https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=141195


If that doesn't work, I found a few folks who had a similar problem here:
https://www.raspberrypi.org/forums/viewtopic.php?p=90223

About halfway down, they mention that it's missing a certain kernel
module; perhaps that might help you.

--
A positive attitude may not solve all your problems, but it will annoy
enough people to make it worth the effort.

GPG Key:
4096R/50441726610D5AE0
fingerprint = 0769 AFCF 681E F61E 2137 F4CB 5044 1726 610D 5AE0