While working on a US Government Supercomputer, I ended up having to connect my Thinkpad to the Fan Power control module via Ethernet ( http://goo.gl/U36iMy ) I also had to connect to the serial port of the InfiniBand Switch for some configuration changes. Which is the topic of this post. That is Linux well Unix based systems use /dev/ttl0 for boot up messages and then use it for the default terminal. On IBM Power systems you can fully configure hardware via open firmware on TTL0. I only mention this since anyone who grew up in a Windows world expects bios and boot to be on the video card.
Thus a good system admin knows how to hookup a serial cable to a Unix server and discover the reason for the hang during boot do to messages on TTY0 and/or fix network settings since the box was unreachable. The Raspberry Pi does have a serial port that you can use to watch boot and also fully configure or access the board. Please see this article: http://putokaz.wordpress.com/2013/03/12/raspberry-pi-rs232-serial-interface-options-revisit/ I was able to find the 4 pin to USB connector on eBay for $1.50 shipped. The Prolific PL2303HX chip that is used will become /dev/ttyUSB0. Thus you can use your favorite comm program ( I suggest Putty or gtkterm ) use that as the connection along with “115200, N, 8, 1” and you'll have full access to your Pi from a Laptop or PC. Windows and Apple users will have to find the correct drivers, once installed it should show up as a “com” port like “com4” as an example. There are two points here: 1. You don't need to connect your Pi to a monitor and keyboard to do project development. With this $1.50 cable you can fully control the Pi. Good to have in case you mess up the network connection etc. Also when embedding the Pi into a large project, say a museum exhibit connecting a simple USB cable to a laptop will be a quick affordable way to gain access to the Pi. 2. While using the Pi in a classroom the instructor can demonstrate critical Admin trouble shooting skills. As on my recent on-site a simple serial connection is used to trouble shoot and configure even the most expensive equipment. These same methods of critical thinking can be thought with a simple $35 Pi and a $1.50 cable! -- Joe /** ** Joseph T Apuzzo ** High-Performance Computing File Systems Expert ** Supporting Linux, Windows, AIX, Linux LPIC-1 certified ** ** http://www.linkedin.com/in/japuzzo/ ** http://apuzzo.us ** ** PGP/GPG Key ID# Short: 0xA16E26CF Long: 0x2DAA3D75A16E26CF ** FingerPrint: 19A8 44EC F650 782B 6770 BF0E 2DAA 3D75 A16E 26CF **/ _______________________________________________ Mid-Hudson Valley Linux Users Group http://mhvlug.org https://mhvlug.org/cgi-bin/mailman/listinfo/mhvlug Upcoming Meetings (6pm - 8pm) Vassar College * Nov 5 - Modern Dns Is Cooler Than You Thought! Dec 3 - Home Disaster Recovery Jan 7 - When Will Then Be Now? Soon.
