Now I am using DS9490R, but it is very unreliable. I now I have 6 DS18B20,
2 D2406, DS2408 and 2 DS2438. The network is about 50m long (twisted pair,
UTP-5). I can say, that DS9490R is totally not suitable for me. Devices
appear and disappear randomly, same device appears multiple times,
sometimes it is impossible to read or write a value. As I added one DS2438
more, network became unusable.

It will be great if DS2482-x00 will be more reliable in long networks. I'll
try to build adapter provided by Patryk and test it this week.


Best Regards,

Ivan, PhD


On Mon, Apr 23, 2012 at 1:25 PM, Chris Lautre <chris.lau...@karusoft.com>wrote:

>
> I would be very interested in a USB to 1Wire Hub with 8 1 Wire ports.
> This would eb much better than using multiple  DS9490R.
>
> Chris
>
>
> On 22/04/2012 10:42, Patryk wrote:
> > I propose a new USB 1-wire adapter.
> > The DS2490 native USB 1-wire adapter is no longer in production. I think
> > you can still buy built adapters from Hobbyboards but if You want to
> build
> > your own it's nearly impossible to source this chip. The popular solution
> > is to use DS2480B with some serial to USB converter like FT232 it behaves
> > then like native DS2490.  However if one plans to have w big 1-wire
> > network with multiple branches the better way seems be DS2482-800 which
> is
> > basically a 1-wire master with one bus  connected to a 8 port hub. You
> can
> > have then a star topology. Again You can still(not sure) buy a hub from
> > Hobbyborad to achieve the same goal but the hub chip is also out of
> > production. So if you are familiar with soldering iron this is a solution
> > for you.
> >
> > The DS2482-800 uses I2C bus. The conversion form I2C to USB is handled by
> > Atmega8A  which is a 8 bit microcontroller and runs a special program.
> > It's a very popular chip it costs about $2(at least in Poland). However
> > You have to upload the firmware to it for which you need a programmer. If
> > you don't have one but you have an old PC with parallel port you can
> build
> > one with few resistors and a plug. Also Raspberry Pi can program AVR
> chips.
> > First I run i2c-tiny-usb
> > http://www.harbaum.org/till/i2c_tiny_usb/index.shtml on Atmega8
> > but there was a performance issue. The read from DS18B20 took about 3
> > seconds
> > and without specifying the bus about 10. Compared to 1.5 with DS2480 and
> > similar
> > time connected to vga i2c port.
> > Fortunately there is a derivative project from Till's i2-usb-tiny it's
> > called OSFI(Open Source InterFace) . It's part of a project called
> > OpenServo http://www.openservo.com/StepByStep
> > It uses Atemga8 and has better performance because it uses some built in
> > i2c(do not know exactly).
> >
> > Here is the whole circuit. I think it's pretty explanatory. For testing
> > You can omit the voltage regulator and power it directly from USB and not
> > using the diodes should be fine for most computers. I done my prototype
> on
> > a breadboard and it works fine.
> > http://ubuntuone.com/6uM1yQRB36zgGEFDxrTc7c
> >
> >
> > On the 1-wire side DS9503 are not essential to get it running they just
> > protect the bus from electrostatic discharges. However they are cheap. I
> > used RJ-12 connectors (telephone) There are different standard's of
> wiring
> > the additional +5V the RJ45 are also popular. You can use screw
> connectors
> > as well. I think I will use 4 RJ45 for longer cables and if more power is
> > needed and  RJ12 for thermometers.
> >
> > After assembling it on a breadboard You have to program the uC the
> > firmware can be downloaded from OpenServo cvs.
> >
> http://www.openservo.com/viewcvs/OpenServo/Interfaces/OpenServo_InterFace/driver/Version_2/firmware/?root=cvs
> > You need main.hex
> > avrdude -c usbasp -p atmega8 -U lfuse:w:0x9f:m -U hfuse:w:0xc9:m -U
> > flash:w:main.hex
> >
> > Then you can test if it's recognized by the system
> > lsusb shows
> > Bus 001 Device 005: ID 1964:0001
> > There is no name for it
> >
> > Then you have to compile kernel module
> >
> http://www.openservo.com/viewcvs/OpenServo/Interfaces/OpenServo_InterFace/driver/Version_2/kernel/?root=cvs
> > make
> > sudo make install
> > sudo depmod -a
> >
> > sudo modprobe osif
> >
> > sudo modprobe i2c-dev
> >
> > then
> > sudo i2cdetect -l
> > should show something like this
> > i2c-0 i2c             OSIF at bus 001 device 005              I2C adapter
> >
> > Then you can run owfs
> > sudo owfs –i2c=/dev/i2c-0 /mnt/owfs
> > You can also use the parameter
> > --i2c=ALL:ALL  and owfs will look at every i2c device. However there is
> > some bug in older version an you might get segmentation fault. It is now
> > fixed in CVS
> >
> > The you should get something like this
> > sudo ls /mnt/owfs
> > bus.0
> > bus.1
> > bus.2
> > bus.3
> > bus.4
> > bus.5
> > bus.6
> > bus.7
> > settings
> > structure
> > uncached
> > statistics
> > system
> >
> > Here's the whole Eagle project the board is half done
> > http://ubuntuone.com/32tUJtqRyNr3ngTsApwW83
> > and how it looks like on a breadboard
> > http://ubuntuone.com/0CUuACUSJMW69aK2FznM6i
> >
> >
> > Pleas give tips how to improve this tutorial. The board is on the way.
> >
>
>
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