On Thu, Oct 03, 2013 at 11:40:05AM -0400, Nick Holland wrote: > 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
Don't use the USB connector to power the board, you will have problems in the future. The BBB runs at 550mhz by default. Some drivers of u-boot (not available yet in the official source code) will check if your board is connected to the USB port or the real power connector. The driver won't increase the cpu speed to 1ghz if you're using the USB connector. Even if our ARM crew implements an OpenBSD driver to select the cpu speed, the OpenBSD driver can't increase the speed beyond of the limit imposed by u-boot. > 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. > -- Juan Francisco Cantero Hurtado http://juanfra.info
