Serial Cable HOWTO
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Communications FAQ
This is the Communications FAQ -- how to talk to your RoboSkiff board.
Workstations
Any computer with a working serial port and the Java JDK can program the
RoboSkiff controller board. The HP Apollo workstations in the 6th floor
EECS lab should have serial cables already attached to the back, along with
the machines in the 6.001 lab on the 5th floor. Please don't take the
cables -- make your own if you want one to use with
your home computer.
Connectors
The RoboSkiff controllers use RJ-10 jacks. These are the same jacks found
on a telephone->handset connection. These should not be confused with RJ-11
jacks, which is what goes between the phone and the wall. RJ-10 jacks are
smaller. Please don't try to force a RJ-11 jack into the Roboskiff
board. Yes, people have tried in the past, so that's why I have to write
this FAQ entry.
Comm Settings
The communications settings for the RoboSkiff controller should be set to
38400 baud, No parity, 8 data bits, and 1 stop bit. Hardware flow control
should not be enabled.
Terminal Programs
Pretty much any terminal program capable of talking over a serial port
and transferring files via the xmodem protocol should be able to
connect to the controller. Here are a few links to programs which have
been tested and are known to work:
TroubleShooting
Here are some frequent problems and fixes for them:
Q: I can't seem to access the serial port on my Windows NT PC
You have to be Administrator or have Administrator access on a NT
machine to access the serial port
Q: How do I quit Minicom?
Use Ctrl-A, Q.
Q: I turned on the board and got lots of garbage
It's likely that your communications settings are screwed up. See the
above FAQ entry. Also make sure you don't have hardware flow control
turned on.
Q: I turned on the board and get some proper output but also lots of garbage
You are probably running more than one copy of minicom.
You should never run more than one copy of minicom at a time.
Doing so screws up the connection.
Q: I can see the board's output fine, but I can't type anything in!
This has been likely caused by you forgetting to turn off hardware
flow control in your minicom settings.
Q: Minicom crashed, and now I get all sorts of odd output
The serial port has gotten confused due to the crash. Reboot your computer
and rerun minicom. If this happens under Windows, do the same thing.
Q: Minicom just doesn't seem to want to talk to the board
Check and make sure you are using the correct serial port. Under
Linux, that port is usually /dev/ttySx (where x is a number from
0-3). Make sure you also have permissions to read/write the serial
port -- check with your system administrator.
Q: Minicom can't seem to download files to the board
The xmodem protocol used by RoboSkiff doesn't seem to agree with the
built-in xmodem that comes with minicom very much. You need to
download this file xm.c, compile it, and use that instead of whatever
comes with minicom. See the minicom documentation for details on how
to do this.
Q: My laptop downloads files for a little while, but then stops.
Is your laptop running off of batteries and has power saving enabled?
Try disabling power saving. Some laptops try to save power by turning
off the serial port if there is no keyboard activity for some time. A
file transfer takes a long time, and most people probably don't touch
the keyboard while things are downloading, so that is when this
behavior exhibits itself.
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