In cases when a shallow FIFO is requested the synthesizer infers distributed RAM
instead of block RAMs. This can be an issue when the clocks of the FIFO are
asynchronous since a timing path is created though the LUTs which implement the
memory, resulting in timing failures. Ignoring timing through the path is not a
solution since would lead to metastability.
This does not happens with block RAMs.
The solution is to use the ad_mem (block RAM) in case of async clocks and letting
the synthesizer do it's job in case of sync clocks for optimal resource utilization.
The XFER_END state defines the end of a transaction, when the entire
data set is written or read to/from the DDRx memory.
A transaction can contain multiple Avalon bursts. Make sure that the FSM
goes back into staging phase at the end of each burst; also define a
signals which indicate the end of each burst for control.
The dac_xfer_req should indicate one single thing, that the FIFO is in
read phase. Should not be affected by any signals, which indicates data
validity on any interface. (e.g. dac_valid)
This signal is not used by the device core, its main purpose is to
indicate the state of the interface for a posible intermediat processing
module.
+ Build both the read and write logic around an FSM
+ Consistent naming of registers and wires
+ Add support for burst lenghts higher than one, current burst lenght
is 64
+ Fix all the bugs, and make it work (first bring up with
adrv9371x/a10soc)
By adding support for partial avalon transfers (data width < bus width),
valid data set size (DMA transfer length) will be dependent on the DMA bus
width only.
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
Istvan Csomortani
Laszlo Nagy