On 10/03/2013 10:18 AM, Jan Stary wrote:
Dear BBB users,
I just bought me a BeagleBone Black board,
and want to install the latest snapshot.
Firstly, OpenBSD/beagle is dead,
replaced by OpenBSD/armv7, right
yep.
Secondly, I need a serial cable to connect to the board.
http://circuitco.com/support/index.php?title=BeagleBone_Black_Serial
mentions 6pin cables that do not quite look like the serial cable
I have always used. (The serial cables linked from that page
are about $20 each - which is about half the price of the board.
Am I missing something?)
yeah. $20. :)
keep in mind, for the intended use, you aren't supposed to need the
serial i/o. OpenBSD isn't the intended use.
The good news is that one serial device will support as many boards as
you wish to use. One at a time, of course.
Should the other end of the serial cable
be the traditional RS-232 connector,
not without an level changing electronics.
or do serial/USB cables also work?
Specifically, have you succesfully used any
of the following with the BeagleBone Black?
http://www.digikey.com/product-detail/en/TTL-232R-3V3/768-1015-ND/1836393
http://www.newark.com/jsp/search/productdetail.jsp?SKU=34M8872
https://www.sparkfun.com/products/9717
http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm
https://www.adafruit.com/products/70
http://www.adafruit.com/products/954
http://www.logicsupply.com/products/ss_ttl3vt
http://dx.com/p/arduino-pl2303hx-to-usb-ttl-upload-download-wire-black-100cm-199553
http://dx.com/p/ft232-to-usb-ttl-wire-integrated-terminal-cable-for-programmer-black-95cm-203717
Those should all work.
The signals are standard RS232 with a huge exception: they are NOT the
normal +/- voltage swing of an RS232 chip, instead they are 0-3.3v, and
much more than that will break things.
SO...you either need RS232 line drivers and receivers going to 3.3v
(which will require a power supply), or use one of the USB->3.3v serial
do-hickies out there that use the USB power supply. That's easier,
really. So these devices have a USB -> serial chip (usually made by
FTDI) and no other line drivers, leaving the voltage level at the 0-3.3v
needed for the BBB.
The good news is probably all those devices will work. Apparently, FTDI
has managed to make a de-facto standard six pin serial interface. IIRC,
the Beaglebone Black only uses three pins anyway (ground, td, rd).
Curiously, it is enough of a de-facto standard that I had difficulty
verifying the pinout on the BBB.
I have managed to buy a couple devices that are little boards with a six
pin connector on one side and a mini-USB on the other. They look cute,
and the board provides a crude keying so you can't put the board in one
way as easily as the other way. Problem is, in the boards I have, the
way it plugs in easily is the WRONG way (bending the pins can permit it
to be directly plugged in, but it's ugly). So stick with the types of
cables you have listed above -- USB on one side, six pin on the other.
Lastly, does the amrv7 platform have its own mailing list?
As the beagle support is a work very much in progress,
what is the discussion I should follow?
arm@ would work.
For what it is worth, I have two BBB's attached to a 2x12x12 block of
wood (that's US wood inches, which translates to around the size of a
hardbound book), with a five port switch and a seven port USB hub and a
power strip screwed to it The BBB's get their power from the USB hub
and the serial device plugs in there (I've mounted the serial device to
the board and added wires to the BBS's). Kinda silly to be bolting tiny
things to a big block like that, 'cept it keeps them and their wires
under control...
Nick.
