Minor glitch in Pi Start Guide


15 posts
by cjw43 » Fri Jan 25, 2013 2:27 pm
Is this the right place to post what appears to be a documentation problem?

The Pi Start Guide has:
Port_Name: Linux automatically assigns different names for different types of serial connectors.
Choose your option:
• Standard Serial Port: ttyS0 ... ttySn
• USB Serial Port Adapter: ttyUSB0 ... ttyUSBn
• Speed: 115200
• Bits: 8
• Parity: None
• Stop Bits: 1
• Flow Control: None
The Serial Port is generally usable by the users in the group dialout. To add oneself to
the group dialout the the following command needs to be executed with root privileges:
$useradd -G {dialout} your_name
2.2.3. Super Easy Way using GNU Screen
Enter the command below into a terminal window
screen Port_Name 115200
_______________________
The Pi says:
pi@raspberrypi ~ $ screen ttyS0 115200
-bash: screen: command not found
pi@raspberrypi

Colin W.
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by cmatthews » Fri Jan 25, 2013 6:43 pm
Screen isn't installed in the standard Raspbian distribution. I guess that the guide could explicitly tell the reader to install it first, but then if they are looking to connect to a serial interface with screen, they will probably know to go and install it.
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by jojopi » Fri Jan 25, 2013 7:18 pm
cjw43 wrote:The Pi says:
pi@raspberrypi ~ $ screen ttyS0 115200
-bash: screen: command not found
The instructions you were following were to allow you to connect to the Pi from another computer, if you had an appropriate serial cable with voltage conversion.

You have not said where you got the "Pi Start Guide" from. In a document published by RS Components at one time, the serial connection was in a section headed "Advanced Setup (Geeks Only)".

The Foundation's Quick Start Guide is here: http://www.raspberrypi.org/quick-start-guide . I think you have already completed most of those steps.
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by cjw43 » Fri Jan 25, 2013 8:44 pm
Thanks for the response.
I should have explained that I currently connect to the Pi from a PC using PUTTY. In general this mode performs satisfactorily.
The aim of using the "screen" command was to explore the possibility of using the HDMI monitor for screen output.

Colin W.
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by cjw43 » Fri Jan 25, 2013 8:56 pm
jojopi wrote:
cjw43 wrote:The Pi says:
pi@raspberrypi ~ $ screen ttyS0 115200
-bash: screen: command not found
The instructions you were following were to allow you to connect to the Pi from another computer, if you had an appropriate serial cable with voltage conversion.

You have not said where you got the "Pi Start Guide" from. In a document published by RS Components at one time, the serial connection was in a section headed "Advanced Setup (Geeks Only)".

[cjw]Yes, you have identified the 13 page document I referenced It carries the Raspberry logo, but no date or author indications..



The Foundation's Quick Start Guide is here: http://www.raspberrypi.org/quick-start-guide . I think you have already completed most of those steps.

[cjw] That is a two pager and doesn't address the issues on which I'm seeking help.

Colin W.
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by cjw43 » Fri Jan 25, 2013 9:05 pm
cmatthews wrote:Screen isn't installed in the standard Raspbian distribution. I guess that the guide could explicitly tell the reader to install it first, but then if they are looking to connect to a serial interface with screen, they will probably know to go and install it.


Thanks for the above. As is explained in an earlier posting, My aim is to use a HDMI monitor. Two questions arise:

Is there some simple way to install the screen command, perhaps by apt-get?

Is the use of screen a necessary step towards using HMDI?

Colin W.
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by alexeames » Fri Jan 25, 2013 9:06 pm
Code: Select all
sudo apt-get install screen


A fuller explanation on my blog. I'll find you a link

http://raspi.tv/2012/using-screen-with-raspberry-pi-to-avoid-leaving-ssh-sessions-open

Very useful program indeed. One of the first things I install when I flash a new SD card.

As far as I know, screen has precious little to do with HDMI. It's a program that allows you to create tty instances and attach and detach at will.
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by cjw43 » Fri Jan 25, 2013 9:10 pm
cmatthews wrote:Screen isn't installed in the standard Raspbian distribution. I guess that the guide could explicitly tell the reader to install it first, but then if they are looking to connect to a serial interface with screen, they will probably know to go and install it.


I should also have explained that I am currently using Wheezy. When I have resolved the basic problems, I plan to install Rasbian.

Colin W.

PS I have the Halfacre Upton book on order,
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by jojopi » Fri Jan 25, 2013 9:27 pm
cjw43 wrote:Yes, you have identified the 13 page document I referenced It carries the Raspberry logo, but no date or author indications..
The version I have says on page 1, "RS Components Vsn 1.0 3/2012".
I should have explained that I currently connect to the Pi from a PC using PUTTY. In general this mode performs satisfactorily.
The aim of using the "screen" command was to explore the possibility of using the HDMI monitor for screen output.
In the instructions you were following, you were supposed to have screen installed on your other computer, not the Pi, as a terminal emulator. You are using PuTTY as your terminal emulator, and a network connection instead of serial. Your configuration is more flexible.

Not sure what you mean you mean by "using the HDMI monitor for screen output". Do you at least see boot messages on the monitor? Video and 3D programs such as omxplayer will use the monitor output automatically, even when run remotely. Most text programs send their output to the machine you are typing on.
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by cjw43 » Fri Jan 25, 2013 9:34 pm
alexeames wrote:
Code: Select all
sudo apt-get install screen


A fuller explanation on my blog. I'll find you a link

http://raspi.tv/2012/using-screen-with-raspberry-pi-to-avoid-leaving-ssh-sessions-open

Very useful program indeed. One of the first things I install when I flash a new SD card.

As far as I know, screen has precious little to do with HDMI. It's a program that allows you to create tty instances and attach and detach at will.


Beautifully simple. Thanks.

I have implemented screen but I don't see how that helps me with HDMI.

I does seem likely to help with another problem. When I attempt to exit, I am told that there are n jobs running.

I shall read your raspiTV posting more carefully.

Thanks,

Colin W.
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by cjw43 » Fri Jan 25, 2013 9:57 pm
jojopi wrote:
cjw43 wrote:Yes, you have identified the 13 page document I referenced It carries the Raspberry logo, but no date or author indications..
The version I have says on page 1, "RS Components Vsn 1.0 3/2012".
I should have explained that I currently connect to the Pi from a PC using PUTTY. In general this mode performs satisfactorily.
The aim of using the "screen" command was to explore the possibility of using the HDMI monitor for screen output.
In the instructions you were following, you were supposed to have screen installed on your other computer, not the Pi, as a terminal emulator. You are using PuTTY as your terminal emulator, and a network connection instead of serial. Your configuration is more flexible.

My error, the indication is at the bottom of page 1. So screen is of no value in my situtation?

Not sure what you mean you mean by "using the HDMI monitor for screen output". Do you at least see boot messages on the monitor? Yes, all the Linux messages appear as expected

Video and 3D programs such as omxplayer will use the monitor output automatically, even when run remotely. Most text programs send their output to the machine you are typing on.
. I am not at the stage of trying out a player, but would like to route the output to the HDMI monitor. I have not yet been able to use VCN with the Wheezy version of Debian.

Later, I hope to be able to use HDMI with VCN, expecting to be able to display graphics from midori.


Thanks again for your help.

Colin W.
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by terrycarlin » Fri Jan 25, 2013 10:05 pm
Have you tried to plug in the HDMI monitor? It should just work. You don't need anything special to use it.
If it ain't broke, take it apart and see how it works.
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by cjw43 » Fri Jan 25, 2013 11:27 pm
terrycarlin wrote:Have you tried to plug in the HDMI monitor? It should just work. You don't need anything special to use it.

Yes, it is connected, but no signal is received with Wheezy.

Colin W.
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by buteman » Sat Jan 26, 2013 1:04 pm
So you are saying that you have your monitor connected to the Pi via an HDMI lead but when you turn them on you see nothing on the monitor?

If so then first try turning off the Pi and the monitor. Switch the monitor on and wait 30 seconds.
Turn the Pi on and see what happens.
Do you see >> anything at all << happening on the monitor?

If not switch Pi and monitor off. connect a different HDMI lead an repeat the above.
If it still doesn't work then repeat it with a different SD card.
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by cjw43 » Sat Jan 26, 2013 1:26 pm
Thanks. I've tried the different switch on times.

I only have one SD card with Wheezy on it.

Colin W.
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