----- Reply message -----
From: "Scott Sullivan" <scott@xxxxxx>
To: "Robert Moskowitz" <rgm@xxxxxxxxxxxxxxx>
Cc: "arm@xxxxxxxxxxxxxxxxxxxxxxx" <arm@xxxxxxxxxxxxxxxxxxxxxxx>
Subject: [fedora-arm] Problems with a pogoplug v02
Date: Tue, Apr 16, 2013 8:58 pm
On 04/16/2013 06:58 PM, Robert Moskowitz wrote:
>
> On 04/16/2013 05:40 PM, Scott Sullivan wrote:
>> On 04/16/2013 05:24 PM, Robert Moskowitz wrote: I am looking at the
>> instructions at
>>>
>>> http://fedoraproject.org/wiki/Architectures/ARM/F18/GuruPlug
>>>
>>> And am I suppose to be using a serial port during this first boot? I do
>>> have a USB serial device, but I would need that on my linux notebook for
>>> a serial port. Oh, wait, I have an old XP notebook with a serial
>>> port... If this USB serial device works, do I use a 'regular' serial
>>> cable (whatever that is these days) and what port settings do I use?
>>
>> /!\ Do Not Use a normal serial adapter/port! The logic levels will be
>> at 12volts and will fry your pogoplugs UART.
>>
>> The pogoplus expects 3.3V logic level.
>> I personally use one these https://www.sparkfun.com/products/9873
>
> Where does this get plugged into? Do I break open the case? All I see
> on the outside is power, LAN, and 4 USB ports.
Internal Header, this is a good photo.
http://www.hack247.co.uk/hack247/wp-content/uploads/serialport.jpg
I've got a little adapter cable I built to go from the JST connector for
the serial to the correct pins on that USB to 3.3v Serial adapter.
You'll find the vast majority of arm devices do not have proper 12v
RS232. Instead they have a UART which is serial with only the TX, RX and
GND lines. The usually operate at the core logic voltage of the SoC and
if you apply the wrong voltage you'll fry the UART.
Most of my devices have had 3.3v serial UARTs including the openWRT
capable routers I experiment with, so I invested in that adapter. It's
served me rather well as I can easily us jumper wires for custom adapter
cables for each board.
--
Scott Sullivan
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