All input and output delays should be referenced to a virtual clock.
If the input and output delays reference base clocks or PLL clocks rather than
virtual clocks, the intra- and inter-clock transfer clock uncertainties,
determined by derive_clock_uncertainty, are incorrectly applied to the I/O ports.
See mnl_timequest_cookbook.pdf for more info.
By defualt the supported tool chain is Quartus PRO. If you want to
build the project with Quartus Standard, you need to define an environment
variable called QUARTUS_PRO_ISUSED with the value 0. (e.g. export
QUARTUS_PRO_ISUSED=0 )
Note: Not all projects going to build on Quartus Standard, you should
fix the errors if there is any.
Optimize the oversampling mechanism.
The behavior of the axi_dac_interpolate was changing if a debug module was
added to the core.
The current code has a better utilization and reliability.
When using an oversampling of 2 for axi_dac_interpolate the rate was
the same as with oversampling by 1(bypassing).
This commit removes the bypass for the ratio of 2.
For projects where the clock ratio between the sampling clock and core clock
is higher than 2, the ad_dds generates a number of samples equal with
the clock ratio. There is a phase offset between the samples, proportional
with the requested DDS frequency.
In scenarios where the DDS out frequency is closer to the upper
limit(Nyquist) and/or the clock ratio is also greater than 2 and the
dac_data_sync reminds low for an extended period of time, the DAC will
receive at each core clock period, a number of samples equal with the
clock ratio and with an amplitude influenced by the DDS out frequency.
In most cases similar with a sawtooth signal.
With this commit we ensures that samples received by the DAC are 0 for
the period where dac_data_sync signal is high. Only when the signal
transitions to low, the phase accumulator is initialized and the phase
information is passed to the phase to amplitude converter.
Another issue can appear when the sync signal is too short; less then
CLK_RATIO * clock cycles. Because the phase accumulator will not
synchronize at all stages, the final result will be a random combination of
sine-waves. Added a minimum sync pulse after the dac_data_sync is set
low.
When frame alignment error monitoring is enabled and error threshold is met
at least for one lane, generate an interrupt so software can reset the link and
do further bring-up steps.
Istvan Csomortani
Laszlo Nagy
AndreiGrozav