:: [DNG] rpi3 serial console
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Autor: Gregory Nowak
Data:  
Para: dng
Assunto: [DNG] rpi3 serial console
Hi all.

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.

Greg


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