Saturday, August 30, 2014

Backup monitor?

If you set up your serial port for communications and have a serial terminal (some systems may require a usb adapter), you will never worry about not having a monitor for emergencies. (Connecting in this case to an nslu2 running linux.)



Notes from an earlier article to set up serial communication, Your system may vary.
Now to get the Pda working with the unit. The Palm pda will not work as is as a dumb terminal, so I had to install a program on to it from another computer called ptelnet.prc using a usb to serial interface. The Palm has an interface cable that will plug directly into the 9 pin serial port on the back of the computer. HP Journa has a standard rs232 port.

$  pilot-xfer -p /dev/ttyUSB0 -i ptelnet.prc

That should be easy. First to test the port. Strange the serial port on what is commonly known as com2:. (com1: =ttyS0)

$ sudo /sbin/getty -h -L /dev/ttyS1 9600 vt100 &
$ sudo chmod 666 /dev/ttyS1

A prompt did not show up on the Palm pda. Now what is the problem? Time to log out and restart the computer to go into the bios. Went into the bios and noticed there were two serial ports, but you could only have one port working at a time. The motherboard was set for the second port which was IR only. Changed the motherboard to use port 1 and disabled IR. Saved the settings and rebooted. Used the temp command again to test the serial port.
 
$ sudo /sbin/getty -h -L /dev/ttyS0 9600 vt100 &
$ sudo chmod 666 /dev/ttyS0
 
The login prompt came right up on the Palm pda. Logged in and all was well. Beginning to feel like Sherlock Holmes solving issues.  Sshed back into Robotpet. Now I had to make the port available all the time.

$ sudo vim /etc/inittab

Needed to uncomment on line to make that so. (i.e. remove the pound sign)

Changed:
# T0:23:respawn:/sbin/getty -L ttyS0 9600 vt100
to
T0:23:respawn:/sbin/getty -L ttyS0 9600 vt100

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