Re: [Discuss-gnuradio] [USRP-users] what is the largest data transfer rate between fpga and overo in e100

[Page Jack]

Hi Philip,
How does the conclusion be made that ARM can not swallow the current
max data transfer rate? I need to build a project that need to process
60MB/s data, so any way to achieve my goal. Use a more powerful CPU or
use dsp on the omap?

On 5/25/12, Philip Balister <address@hidden> wrote:
> On 05/24/2012 09:46 PM, Page Jack wrote:
>> Thanks Ben,
>> does e100 use EMIF to transfer sample data between FPGA and ARM? If so
>> the
>> data rate should be able to improved.
>> Anyone have tried to improve the data rate?
>
> EMIF is basically identical to GPMC. The interface uses DMA to move data
> in 2K chunks between the FPGA and memory. This is the largest transfer
> possible due to how we connected the address and data lines
>
> My impression of the current limiting factor is interrupt response time.
> There is probably some room for small improvements, but as Ben notes, we
> are already collecting data faster than the ARM can swallow it.
>
> Philip
>
>>
>> Regards
>>
>> On Thu, May 24, 2012 at 9:01 AM, Ben Hilburn <address@hidden>
>> wrote:
>>
>>> The CPU sets up the initial DMA parameters, but from then on, it's pure
>>> DMA.  No CPU is required.
>>>
>>> Cheers,
>>> Ben
>>> ----------------------------
>>> Ben Hilburn <http://goo.gl/5DdZ3> @ Ettus Research,
>>> LLC<http://www.ettus.com/>
>>>
>>>
>>>
>>> On Wed, May 23, 2012 at 5:55 PM, Page Jack <address@hidden>
>>> wrote:
>>>
>>>> Thanks, does the ARM memory bus use DMA or it eat cpu?
>>>>
>>>>
>>>> On Thu, May 24, 2012 at 5:06 AM, Ben Hilburn
>>>> <address@hidden>wrote:
>>>>
>>>>> Page -
>>>>>
>>>>> The memory bus to the ARM provides 40 MBytes / second.  This is used
>>>>> for
>>>>> streaming samples, as controlled via software.  Currently, UHD supports
>>>>> 16
>>>>> bit and 8 bit samples for TX & RX.  The GPMC can only going to talk to
>>>>> one
>>>>> slave at a time; the possible slaves are TX, RX, and ethernet.  So you
>>>>> can
>>>>> only be sending TX samples, receiving RX samples, or communicating via
>>>>> ethernet.
>>>>>
>>>>> Thus, doing the math with the numbers above, you can stream:
>>>>> 16 bit I, 16 bit Q -- Total: 32-bit samples -- @ 10 MSps
>>>>> 8 bit I, 8 bit Q -- Total: 16-bit samples -- @ 20 MSps
>>>>>
>>>>> What you choose to do with this data is obviously up to you. It is
>>>>> very
>>>>> easy to try to do more processing than the ARM can handle, in which
>>>>> case
>>>>> samples will start getting thrown out by UHD.  Thus, you can typically
>>>>> process between 4 and 8 MHz of baseband bandwidth, depending on your
>>>>> application.  If you are willing to dig deep into the code to make NEON
>>>>> and
>>>>> C64 optimizations, you can improve the performance dramatically.
>>>>>
>>>>> Cheers,
>>>>> Ben
>>>>> ----------------------------
>>>>> Ben Hilburn <http://goo.gl/5DdZ3> @ Ettus Research,
>>>>> LLC<http://www.ettus.com/>
>>>>>
>>>>>
>>>>>
>>>>> On Tue, May 22, 2012 at 7:47 PM, Page Jack
>>>>> <address@hidden>wrote:
>>>>>
>>>>>> Hi,
>>>>>> I want to know the overo model used in e100 and the largest data
>>>>>> transfer rate between fpga  and overo in e100.
>>>>>>
>>>>>> Regards!
>>>>>>
>>>>>> _______________________________________________
>>>>>> USRP-users mailing list
>>>>>> address@hidden
>>>>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>>
>>
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>