The clock monitor reports the ratio of the clock frequencies of a known
reference clock and a monitored unknown clock. The frequency ratio is
reported in a 16.16 fixed-point format.
This means that it is possible to detect clocks that are 65535 times faster
than the reference clock. For a reference clock of 100 MHz that is 6.5 THz
and even if the reference clock is running at only 1 MHz it is still 65
GHz, a clock rate much faster than what we'd ever expect in a FPGA.
Add a configuration option to the clock monitor that allows to reduce the
number of integer bits of ratio. This allows to reduce the utilization
while still being able to cover all realistic clock frequencies.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Currently when the monitored clock stops the clock monitor retains the old
frequency ratio value and there is no way to detect that the clock has
stopped and the reported value is indistinguishable form a clock still
running at the right rate.
If a full iteration as elapsed on the monitoring side and there is no
indication that the counter on the monitored side has started running set
the reported clock ratio value to 0 to indicate that the clock has stopped.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Currently the clock monitor features a hold register in the monitored clock
domain. This old register is used to store a instantaneous copy of the
counter register. The value in the old register is then transferred to the
monitoring domain. Since the counter is continuously counting it is not
possible to directly transfer it since that might result in inconsistent
data.
Instead stop the counter and hold the registers stable for a duration that
is long enough for the monitoring domain to correctly capture the value.
Once the value has been transferred the counter is reset and restarted for
the next iteration.
This allows to eliminate the hold register, which slightly reduces
utilization.
The externally visible behaviour is identical before and after the patch.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Make sure that the XML files are re-build when any of the scripts that are
used to generated it are modified.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
All the rules to generate the XML files are the same. Reduce the number of
rules by useing wildcard matching for the rule target.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Sort the entries in the library Makefile alphabetical. Keeping it ordered
makes it easier to track changes compared to randomly reshuffling it
every time a new entry is added.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
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
There are devices which have a asynchronous data ready signal. (asynchronous
with the spi clock) The CDC stages can be enabled by setting up
the ASYNC_TRIG parameter.
Lars-Peter Clausen
Rejeesh Kutty
Istvan Csomortani
AndreiGrozav
Adrian Costina