This feature will allow the user to hold(indefinitely) the last sample, from an
ongoing DMA transfer, simple or cyclic(stooped by user or trigger).
This commit also adds as functionality option:
-synchronized stop between the two channels(DMAs)
-stop by trigger
The previous mechanism was "probing" the DMAs for valid data. Better said,
each interpolation channel enabled it's DMA until a valid data was received,
then it disabled the DMA read and waited for the adjacent channel(DMA) to
receive a valid data. Only when for both channels had valid data on the
DMAs interfaces was the transmission started. This added an undesired and
redundant complexity to the interpolation channels. Furthermore, for continuous
transmission, using the above mechanism lead to a fixed phase(sample)
shift between the two channels at each start.
By using the streaming mechanism the interface is simplified and the
above problems are solved.
The previous channel sync mechanism was simply holding the transmission by
pulling down the dma_rd_en of the two DMAs for each channel(set reg 0x50). After a
period of time (that will take the two DMAs to have the data ready to move)
the dma_rd_en was set for both channels, resulting in a synchronized start.
This mechanism is valid when the two channels are streaming the same
type of data (constant, waveform, buffer or math) at close frequencies.
Streaming 10MHz on a channel and 100KHz on the second one will result
in different interpolation factors being used for the two channels.
The interpolation counter runs only when the dma_transfer_suspended(reg 0x50)
is cleared. Because of this, different delays are added by the interpolation
counter one DMA with continuous dma_rd_en will have data earlier than the
one with dma_rd_en controlled by the interpolation counter. Furthermore,
because the interpolation counter value is not reset at each
dma_transfer_suspended, the phase shift between the 2 channels will
differ at each start of transmission.
To make the transfer start synced immune to the above irregularities a
sync_transfer_start register was added (bit 1 of the 0x50 reg).
When this bit is set and the bit 0(dma_transfer_suspended) is toggled,
the interpolation counters are reset. Each channel enables it's DMA until
valid data is received, then it waits for the adjacent channel to get valid data.
This mechanism will be simplified in a future update by using a streaming
interface between the axi_dac_interpolate and the DMAs that does not require
the probing of the DMA.
The CIC filter introduces different amplifications depending on the
interpolation ratio. By adding a multiplier in the interpolation chain
the amplification can be compensated
All the hdl (verilog and vhdl) source files were updated. If a file did not
have any license, it was added into it. Files, which were generated by
a tool (like Matlab) or were took over from other source (like opencores.org),
were unchanged.
New license looks as follows:
Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
Each core or library found in this collection may have its own licensing terms.
The user should keep this in in mind while exploring these cores.
Redistribution and use in source and binary forms,
with or without modification of this file, are permitted under the terms of either
(at the option of the user):
1. The GNU General Public License version 2 as published by the
Free Software Foundation, which can be found in the top level directory, or at:
https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html
OR
2. An ADI specific BSD license as noted in the top level directory, or on-line at:
https://github.com/analogdevicesinc/hdl/blob/dev/LICENSE
The axi_dac_interpolate does not use the full width of the AXI interface
address. It only responds to register access in the first 32 registers.
Reduce the size of the AXI address to 7 bit accordingly. This allows the
scripts to correctly infer the internal register map size which will cause
the interconnect to filter out access to these unused register.
This slightly reduces utilization by getting rid of some pipeline
registers.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Move the processing pipeline of the axi_adc_decimate core to its own
sub-module. This makes it easier to simulate the processing independent of
the register map.
Also since the filter is two instances of the same logic, one for each
channel, let the new sub-module model one channel and instantiate it twice.
This allows to change the implementation without having to change the same
code twice.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
AndreiGrozav
Arpadi
Istvan Csomortani
Adrian Costina
Lars-Peter Clausen