[USRP-users] Oddity in E1xx FPGA

Almohanad Fayez almohanad.fayez at gmail.com
Mon Jun 18 18:35:34 EDT 2012


John, I just found out that the E100 can in fact read RS232 through
the J86 connector as detailed in the Ettus GPSDO datasheet.  I
apologize for that.



On Thu, May 31, 2012 at 5:49 PM, John Buetefuer
<john.buetefuer at unisa.edu.au> wrote:
> Thanks Almohanad.. Do you know if the up-to-date E100 schematics are
> available? I assume the differences are not huge between revisions, but it's
> always good to have correct information.
>
> Cheers
>
> John
>
>
> On 31/05/2012 2:12 AM, Almohanad Fayez wrote:
>>
>> To answer your FPGA/GPS/serial question,  the FPGA image doesn't read
>> in the RS232 values it just takes PPS and the 10 MHz reference signal.
>>
>>
>> On Tue, May 29, 2012 at 10:10 PM, John Buetefuer
>> <john.buetefuer at unisa.edu.au>  wrote:
>>>
>>> It appears I may have spoken too soon. If I remove these signals the port
>>> stops working, which suggests that I have outdated schematics for the
>>> E100.
>>>
>>> Are the latest E100/E110 schematics available? (Rev4?)
>>>
>>> Cheers
>>>
>>> John
>>>
>>>
>>> On 30/05/2012 1:15 PM, John Buetefuer wrote:
>>>>
>>>> I've just commenced integrating a 3rd party GPS unit (ie, not a GPSDO)
>>>> with an E100 and have noticed the following odd things with the E100
>>>> FPGA
>>>> and schematics.
>>>>
>>>> * The FPGA appears to be driving the overo_rxd1 net (and uart Rx input
>>>> pin
>>>> on the overo) with a signal from the FPGA input pin "fpga_rxd1" (ball
>>>> AB8) -
>>>> which according to my schematics is not connected on the PCB at all
>>>> (presume
>>>> this is pulled high by the FPGA I/O pull-ups).
>>>>  [fpga/usrp2/top/E1x0/u1e.v]
>>>>
>>>>   //
>>>>
>>>> /////////////////////////////////////////////////////////////////////////
>>>>   // UART level conversion
>>>>   assign fpga_txd1 = overo_txd1;
>>>>   assign overo_rxd1 = fpga_rxd1;
>>>>
>>>> overo_rxd1 is defined as an output pin, which sees it driving against
>>>> the
>>>> MAX232 driving this line - surely this is not correct or intended.?
>>>>
>>>> It looks to me that this code may have had some historical purpose on an
>>>> earlier rev of the board, but perhaps with the current version of the
>>>> hardware, is not correct?
>>>>
>>>> On a somewhat related note, can someone confirm that on the E1x0 series
>>>> units, the FPGA firmware does not communicate with the GPSDO unit at all
>>>> (via RS232), and that the UHD accesses the GPS via the Overo serial port
>>>> (ttyO0)?
>>>>
>>>> Cheers
>>>>
>>>> John
>>>
>>>
>>> _______________________________________________
>>> USRP-users mailing list
>>> USRP-users at lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>>
>



-- 
Almohanad (Al) Fayez




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