Hi,
some of you may remember my earlier attempts to add a libftdi based
LinkUSB interface into master. For reference:
http://sourceforge.net/p/owfs/mailman/message/32492037/
In short, the client-timings are generally cut about 2.5 times,
depending on operation. A temp sensor is read in ~50ms instead of
~123ms. More details can be found at the link.
Last time (2014) it was well received, but got stuck on discussions
about different methods of auto-detection (something which isn't too
easy/possible with FTDI). I have since run that code in production
without any glitches, so the ftdi-part has really proven stable.
In the recent days, I've cleaned up the code to not be LinkUSB specific,
but rather work with any serial-based device (and fixed some minor
issues). There is no auto-detection though (and again, I don't believe
that is possible to do reliable with serial devices; see discussions in
above link).
A cut from the (updated) man page is available below, please see that
for usage details.
I realize that this isn't the simplest thing to explain to a user, but
then again, a regular user who don't really care about those extra
milliseconds shaved off each request can easily use the same old
/dev/ttyS0 addressing. For us who *do* care however, it is very useful.
The ftdi parts of the code has been running since 2014, but only with
LinkUSB. But it's mostly the device setup parts which has changed
lately, so it shouldn't be any unstability. I've tested the LinkUSB,
emulated and --link mode, and DS2480 through a FTDi adapter without any
issues.
I've commited all the changes in the new ftdi branch:
http://sourceforge.net/p/owfs/code/ci/2982df8ca648bd9cec4d820151046b044ef504e0/
The above is a clean patch based on my earlier work (which may be
interesting for those wanting to check out how it evolved) at
http://sourceforge.net/u/stromnet/owfs/ci/ca85d64eefaaa9f1e90bbc079db65cfda623c472/log/?path=
One potential issue could be the BUS_close related changes in
ow_connection.c, could someone take a look at that please? I think that
is actually a bug fix, basically it calls device-specific BUS_close
*before* cleaning up and closing the device, instead of after.. But an
extra set of eyes would be great.
Another issue could be that I now bring any link-devices into 19200-mode
after initial detection (also increases the speed a lot). This is the
mode I've been running my LinkUSB during the last years, via the FTDI
layer, so should be OK. But I have not tested with older links, or
non-USB based links (or the linkusb via old serial addressing for any
longer duration).
To sum it up, I hope we can get this branch merged into master sooner
rather than later! If we want to add a sane auto-detection scheme
somehow, let's add that later..
Any testing and feedback is much appreciated!
Regards
Johan
Man-page cut:
-------
* Serial devices
port specifies a serial port, e.g. /dev/ttyS0
If OWFS was built with libftdi support, you may be able to
use the
ftdi: prefix to address a FTDI-based USB device.
For details, see the FTDI ADDRESSING section.
....
FTDI ADDRESSING
FTDI is a brand of USB-to-serial chips which are very common.
If your
serial device is connected via a USB serial dongle based on
a FTDI
chip, or if your adapter uses a built-in FTDI USB chip (for
example,
the LinkUSB), you can use this FTDI addressing.
The main benifit with this mode of access is that we can
decrease the
communication delay, yielding twice as fast 1-Wire
communication in
many cases.
The following values for port can be used to identify a
specific FTDI
port. Note that this requires that OWFS is built with libftdi
support.
ftdi:d:<devicenode>
path of bus and device-node (e.g. "003/001") within usb
device
tree (usually at /proc/bus/usb/)
ftdi:i:<vendor>:<product>
first device with given vendor and product id, ids can
be deci-
mal, octal (preceded by "0") or hex (preceded by "0x")
ftdi:i:<vendor>:<product>:<index>
as above with index being the number of the device
(starting
with 0) if there are more than one
ftdi:s:<vendor>:<product>:<serial>
first device with given vendor id, product id and serial
string
The above formats are parsed fully by libftdi, but with the
ftdi: pre-
fix stripped.
Simplified device serial-only support
An additional format is supported, for certain bus types.
This only
specifies the USB serial number.
ftdi:<serial>
Identifies a FTDI device by serial only. Currently,
this is
only valid for the VID/PID found on the LinkUSB (i.e.
--link).
Note that those VID/PID's are the default for any FT232R
device,
and in no way exclusive to LinkUSB.
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