Serial console cable selection

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After playing with an Rpi2 for a while, it looks like a serial
console cable would be a good idea. The display hosts would be
either an old-ish Intel CoreDuo Imac, with USB ports, or an  
even older but still reliable Intel box with traditional RS-232  
serial ports having 9-pin male dsub connectors.  

For the moment I tend to favor an RPi-RS-232 solution, but
they don't seem common. USB to RPi adapters seem more common,
but it appears they require device drivers, which I'd rather
avoid if possible.

Speed isn't an issue, 9600N81 is fine if the Pi will run that
slow.

Thanks for reading, and any guidance.

bob prohaska
  



Re: Serial console cable selection
On 6/15/2015 11:22 PM, User Bp wrote:
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Pardon me for clarifying, but when you say RPi-RS-232, you mean a  
physical RS-232 cable from the rPi as compared to a USB dongle with an  
RS-232 connector?  The RPi-RS-232 would require a level shifter to match  
the expansion connector serial port to the RS-232 standard.  Is that  
correct?

I believe I have seen these expansion port adapters before.  If you  
can't find one, I would be happy to make one for you.  It is a very  
simple design.  I'm sure you aren't the only person in the world who  
wants to use that serial port.

--  

Rick

Re: Serial console cable selection
On 16/06/15 04:22, User Bp wrote:
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I've made an adapter that connects the Pi to a PC or serial terminal (I  
sometimes use an old Wyse60 terminal).

What you need is a MAX3232 chip (not the MAX232 which runs at 5V instead  
of the 3.3V the Pi needs). You can get ready-built boards with a DB9  
socket on for a few quid. Then just connect them to TxD, Rxd, GND and  
3v3 on the Pi and you're done.

Set the console and terminal speed to whatever you want in cmdline.txt  
and /etc/inittab and you're ready to go.

I use 19200 or 9600 for the terminal, and 115200 for a PC. As there's no  
handshaking it might be wise to set it to a lower rate to avoid buffer  
overruns.

Re: Serial console cable selection

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I used these cables and work without problems.
You need to install a driver on the PC side though.
http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm

Bye Jack
--  
Yoda of Borg am I! Assimilated shall you be! Futile resistance is, hmm?

Re: Serial console cable selection
On 16/06/2015 08:23, Jack wrote:
[]
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Thanks for that pointer, Jack.  These also look very useful:

   http://www.ftdichip.com/Products/Cables/RPi.htm

  
http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_RPi.pdf

GBP 10 + tax from RS components:

   http://uk.rs-online.com/web/p/interface-development-kits/7676200

--  
Cheers,
David
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Re: Serial console cable selection
On Tue, 16 Jun 2015 03:22:49 +0000, User Bp wrote:

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How are you planning to get serial data out of the RPi? Plugging a USB-
Serial adapter into it would be easiest.

You don't say what OS the PC with serial ports is using. As I've used  
serial ports under both Linux and DOS/Windows, here's what I know:

If the PC end is running Linux, there's no general issue because all  
Linuxes have serial port drivers and utilities for setting baud rate,  
parity and stop bits: its serial ports can talk to the usb adapter at the  
RPi end. The standard set of USB Serial drivers and configuration  
utilities should be available for Raspbian.  

I've also used serial ports from DOS/early Windows. I don't know whether  
later Windows (XP or later) now have serial drivers, but I suspect not  
since serial ports have been on the way out from well before XP was  
released. Microsoft has never released serial drivers for either DOS or  
earlier Windows, so an application that used serial ports either rolled  
its own built-in drivers or used a third-party library such as Willies  
COM-DRIV. Programs I've written using COM-DRIV worked well (I used them  
to receive data from serial GPS receivers) and so did Kermit, a program  
that can emulate most serial terminals and do file transfers over serial  
lines.  

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Why not simply use an Ethernet connection? Configured SSH for X.11  
forwarding on the RPi and you will have both textual and graphic apps  
running on a Linux box with nothing more needed. If your PC is running  
Windows, PUtty lets textual apps run and installing one of the OSS X-Term  
packages (Cygwin/X, VcXsrv, XWinLogon) lets the RPi use a graphical  
desktop.

I don't know what you'd need on the iMac, but I'm certain somebody else  
will know about that.
  

--  
martin@   | Martin Gregorie
gregorie. | Essex, UK
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Re: Serial console cable selection
Martin Gregorie wrote:

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I think you can relax on that one!

Every version of Windows has drivers for standard COM: ports and all the  
USB->serial manufacturers provide drivers for their virtual COM: ports

Re: Serial console cable selection
On 16/06/15 10:20, Martin Gregorie wrote:
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The serial USB cable I bought worked out of the box on Debian (initially
to connect to a Pi with a corrupted memory card). Perhaps ironically
(being a port of software written originally for W******), Putty is the
best Linux software I've yet found for serial terminal emulation.

Re: Serial console cable selection
On 16.6.15 21:31, Hils wrote:
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Have you tried:

   screen /dev/ttyUSB0 9600

--  

-TV


Re: Serial console cable selection
On Tue, 16 Jun 2015 03:22:49 +0000, User Bp wrote:

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Wouldn't it be easier to put both on a network and ssh in?

Re: Serial console cable selection
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But that doesn't give you a serial _console_, i.e. a terminal where
the boot messages are sent to and that works even if the system is
unable to go multiuser or something upsets the network settings.
If you are running the Pi headless it is only a matter of time
before you'll need it even if you manage initial set up without
one.

--  
Andrew Smallshaw
snipped-for-privacy@sdf.lonestar.org

Re: Serial console cable selection
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Aye, there's the rub! 8-)

This looks like it might be appropriate:
http://www.nulsom.com/datasheet/NS-RS232_en.pdf

It's DCE, all I have to do is make up a 4 conductor
cable over to the Pi. Soldering up those tiny connectors
will be a challenge.


Does anybody see a fly in the ointment?

Just to clarify, the Intel box is running FreeBSD, so serial
terminal support is there. It's also close to the Pi, so cables
won't be long. The Mac (my terminal) is some distance away. All
three are on Ethernet.

Thanks for reading and replying,

bob prohaska


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