Hi,
Thanks for the reply and sorry for the delayed response.
Yes, the x-axis represent the time and y-axis represents the signed 8 bit
output. The negative bias is due to the nature of the input.
I was trying to use the files in the link you mentioned, but I keep getting
the error shown below. I am using the bof file provided for roach2.
test roach connectivity ... ok
check if requested bof is available ... ok
test roach pingability ... ok
program the requested bof ... ok
estimate clock rate, should be within 1 MHz of expected ... ok
confirm the design has the ADC SPI controller ... ok
confirm the design has the needed scope ... ok
test if calibration finds optimal MMCM phase ... FAIL
======================================================================
FAIL: test if calibration finds optimal MMCM phase
----------------------------------------------------------------------
Traceback (most recent call last):
File "test_adc5g.py", line 107, in test_optimal_solution_found
self.assertIsNotNone(self._optimal_phase)
AssertionError: unexpectedly None
----------------------------------------------------------------------
Ran 8 tests in 7.230s
FAILED (failures=1)
Please let me know if I am doing anything wrong or where could be the
problem.
For your information:
System: roach2
ADC : ASIAA ADC5G ADC
Clock : 2500MHz.
Thanks and regards,
Sharat
On 1 September 2015 at 23:01, Primiani, Rurik <rprimi...@cfa.harvard.edu>
wrote:
> Hi Sharat,
>
> The plot you provided has no labels or units so I will assume the x-axis
> represents time in samples and the y-axis represents signed 8-bit sample
> values. I'm not sure why there is such a negative bias but perhaps that's
> particular to your instrument.
>
> Please, at the very least, run the MMCM calibration described at
> https://github.com/sma-wideband/adc_tests to reduce glitches on the
> interface. I believe Jack also has a more sophisticated approach which
> adjusts the IODELAY for each individual data line; sadly I don't have a
> link handy for that.
>
> Although you may not see these glitches with a sine wave, a noise-like
> signal will cause more transitions on each bit and thus more glitches with
> an uncalibrated interface.
>
> Thanks,
> Rurik
>
>
>
> On Tue, Sep 1, 2015 at 2:54 AM, sharat varma <va...@hku.hk> wrote:
>
>> Hi Jack,
>>
>> Thanks for the reply.
>>
>> I did not run mmcm calibration. Actually, we checked the ADC by feeding
>> it a low frequency sine wave from a function generator and it works fine.
>>
>> The problem with spikes occurs when we feed the ADC with the
>> photo-detector output.
>>
>> Regards,
>> Sharat
>>
>>
>> On 1 September 2015 at 13:52, Jack Hickish <jackhick...@gmail.com> wrote:
>>
>>> Hi Sharat,
>>>
>>> Are you running the adc mmcm calibration routine after programming your
>>> roach?
>>>
>>> Cheers,
>>> Jack
>>>
>>> On 31 August 2015 at 22:41, sharat varma <va...@hku.hk> wrote:
>>>
>>>>
>>>> Hi Casper,
>>>>
>>>> I am working as a post-doc working under guidance of Dr. Hayden So at
>>>> The University of Hong Kong.
>>>>
>>>> We are using ROACH2 to capture data from optical cytometry. We are
>>>> using ASIAA ADC5G ADC to capture data at 4 to 5 Gsps.
>>>>
>>>> We basically use the following parameters.
>>>>
>>>> Block parameter: two-channel, ZDOK0, demux 1:1 .
>>>> System: roach2, clock source:adc0_clk, clock rate: 300 MHz.
>>>>
>>>> We are connecting the output of a photo-detector 1544-B from Newport
>>>> Corp (the spec is attached) to the ADC input using SMA.
>>>> We find that noisy spikes are introduced when we capture the data
>>>> through the ADC (see attached fig). We double checked if the source had
>>>> problems using a oscilloscope, but on the oscilloscope we do not see any of
>>>> these spikes.
>>>>
>>>> We would be grateful if you could let us know if we are doing anything
>>>> wrong.
>>>>
>>>> Rgards,
>>>> Sharat
>>>>
>>>>
>>>>
>>>
>>
>
