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FMC DEL 1ns 4cha - Software
Commit 06eaaa1f authored by Alessandro Rubini's avatar Alessandro Rubini
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doc: documented what we have for output

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doc/fine-delay.in
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......@@ -181,9 +181,10 @@ when this driver is completed.
sudo make modules_install
@end example
@b{Warning:} the commit-ID above is volatile until this driver is
finalized, that's why the command above retrieves the @i{current}
@b{Warning:} the commit-ID above might change in the future,
that's why the command above retrieves the @i{current}
branch @code{for-linux-2.6.32} if the first checkout fails.
I don't plan to change this during May 2012, though.
The procedure for @i{spec-sw} is similar, but the master branch will
......@@ -202,9 +203,10 @@ identifier.
sudo make modules_install
@end example
@b{Warning:} the commit-ID above is volatile until this driver is
finalized, that's why the command above retrieves the @i{current}
@b{Warning:} the commit-ID above might change in the future,
that's why the command above retrieves the @i{current}
branch @code{for-linux-2.6.32} if the first checkout fails.
I don't plan to change this during May 2012, though.
@c FIXME: the commit identifiers.
Finally, you need to compile and install this driver, using the following
......@@ -310,7 +312,9 @@ implementation (@code{fdelay_lib.h}) to avoid trying to compile older
code with new headers.
@item The @i{tools} directory includes standalone tools that access ZIO
directly. Their name begins with @code{fd-raw-}.
directly. Their name begins with @code{fd-raw-} (but there is a
non-fine-delay tool to generate pulses on the parallel port, which has
a different name pattern).
@item The @i{lib} directory includes example programs for the library.
Unfortunately sources of programs and library files both begin with
......@@ -671,24 +675,114 @@ of the motherboard, the address is @code{378}):
@node The Output cset
@section The Output cset
@b{Note:} This is not documentation at this point in time, it is
just material for some brainstorming: the code is not there yet.
The output channels need some configuration to be provided. This
is done using attributes. Attributes can either be written in
@i{sysfs} or can be passed in the control block that sides data.
While in theory we may define the channels as zero-data ones (like the
input channel described earlier), this would prevent a shell user to
configure the output: attributes can be set in @i{sysfs} but then to
fire the action you'll need to write a data block. This would not be
a problem for compiled code, which will just push attributes to the
control device and would be happy with a zero-length data area.
This driver defines the sample size as 4 bytes and the trigger should
be configured for a 1-sample block (the library does it at open
time). We should aim at a zero-size data block, but this would require
a patch to ZIO, and I'd better not change version during development.
The output is configured and activated by writing a control block
with proper attributes set. Then a write to the data channel will
push the block to hardware, for it to be activated.
The following attributes are defined:
@example
/* Output ZIO attributes */
enum fd_zattr_out_idx {
FD_ATTR_OUT_MODE = FD_ATTR_DEV__LAST,
FD_ATTR_OUT_REP,
/* Start (or delay) is 4 registers */
FD_ATTR_OUT_START_H,
FD_ATTR_OUT_START_L,
FD_ATTR_OUT_START_COARSE,
FD_ATTR_OUT_START_FINE,
/* End (start + width) is 4 registers */
FD_ATTR_OUT_END_H,
FD_ATTR_OUT_END_L,
FD_ATTR_OUT_END_COARSE,
FD_ATTR_OUT_END_FINE,
/* Delta is 3 registers */
FD_ATTR_OUT_DELTA_L,
FD_ATTR_OUT_DELTA_COARSE,
FD_ATTR_OUT_DELTA_FINE,
FD_ATTR_OUT__LAST,
};
enum fd_output_mode {
FD_OUT_MODE_DISABLED = 0,
FD_OUT_MODE_DELAY,
FD_OUT_MODE_PULSE,
};
@end example
So, to disable the output, just write 0 to the mode attribute.
To configure pulse or delay all attributes must be written.
@b{Note:} writing to @i{sysfs} is not working with this version of ZIO.
While recent developments introduced more complete consistency between
the various places where attributes live, with this version you can
only write attributes to the control block.
@menu
* Using fd-raw-output::
@end menu
@c --------------------------------------------------------------------------
@node Using fd-raw-output
@subsection Using fd-raw-output
The simplest way to generate output is using @i{fd-raw-output}, part
of the @i{tools} directory of this package. The tool writes a control
block to the ZIO control file, setting the block size to 1 32-bit
sample; it then writes 4 bytes to the data file to force output of the
attributes.
The tool acts on channel 1 (the first) by default, but uses the
environment variable @code{CHAN} if set. All arguments on the command
line are passed directly in the attributes. Thus, it is quite a
low-level tool.
To help the user, any number that begins with @code{+} is added to the
current time (in seconds). It is thus recommended to set the card to follow
system time.
The following example sets card time to 0 and programs 10 pulses at
the beginning of the next second. The pulses are 8usec long and
repeat after 16usec. The next example runs 1s of 1kHz square wave.
For readability, numbers are grouped as @i{(mode, delay), (start --
utc-h, utc-l, coarse, frac), (stop -- utc-h, utc-l, coarse, frac),
(delta - utc-l, coarse, frac)}.
@smallexample
spusa# ./fd-raw-settime 0 0; \
./fd-raw-output 2 10 0 1 0 0 0 1 1000 0 0 2000 0
spusa# ./fd-raw-settime 0 0; \
./fd-raw-output 2 500 0 1 0 0 0 1 62500 0 0 125000 0
@end smallexample
The following example sets board time to host time and programs a single
40us pulse at the beginning of the next second (note use of @code{+})
@smallexample
spusa# echo 0 > /sys/bus/zio/devices/zio-fd-*/command; \
./fd-raw-output 2 0 0 +1 0 0 0 +1 5000 0
@end smallexample
The following example programs a pps pulse (1ms long) on channel 1
and a 1MHz square wave on channel 2, assuming board time is already
synchronized with host time:
@smallexample
spusa# CHAN=1 ./fd-raw-output 2 -1 0 +1 0 0 0 +1 125000 0 1 0 0; \
CHAN=2 ./fd-raw-output 2 -1 0 +1 0 0 0 +1 64 0 0 125 0
@end smallexample
The attributes to be defined are the various parameters of the output
channel: whether it is triggered by the input or is outputting pulses
by itself; the delay; the number of pulses, the two periods, and so
on.
@b{Note:} mode, that should output pulses delayed over the input, is not
currently working.
@c ##########################################################################
@node Using the Provided API
......@@ -969,15 +1063,15 @@ allows:
@item There is no support for White Rabbit at this time.
@item Output support is missing. It simply is not there at this point.
@item Generation of delayed pulses is missing (it is not working)
@item The API for pulse generation is not yet available.
@item We need interrupt support. The input is performed with a kernel timer.
@item There is no EEPROM support. The driver uses default calibration
settings.
@item Offsets for input and output timestamps are not used at this point.
@item We need a module parameter to avoid probing non-fine-delay SPEC
cards. Reading the magic number from an SPEC that is not programmed
(or likely that is programmed with a different gateware) may lock up
......
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