Home Automation: [ha] Question re Dallas 1 Wire

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The question was asked as to what was the maximum line length for the 1 =
Wire bus.
Answer 1
If no slew rate control and active pull up then typically the cable run =
would be limited to 100m.

Answer=20
If slew rate control and active pull up where applied then typically the =
cable run would be limited to 300m.

The cable can be organised in a tree arrangement with branches =
controlled by nodes.

|-------------- I/O ----------- EOL
Controller ----------|
|--------------|----------------I/O + TS =
-------- I/O ----------- EOL
| |---------------- I/O =
--------- I/O --------- EOL
|
|---------------- I/O -------- I/O ------- =
TS ------- I/O -------------- EOL

I/O =3D This is a TO92 shaped device that can be either a 5V =
digital input or open collector output rated at 20mA.
EOL =3D This is a TO92 shaped device with a unique serial number =
internally. This allows you to check if the cable run is function =
correctly.
TS =3D Temperature Sensor in a TO92 Package.

The I/O, TS and EOL use two of there three legs to connected to the bus =
the third leg on the I/O is the actual I/O pin. The third leg on the EOL =
is not used. The third leg on the TS connects to en external 5V Power =
supply.

Typical Prices area as follows
DS2407 $5.00 Each I/O Device
DS1820 $8.00 Each Temperature Sensor
DS2401 $2.50 Each Serial number
DS1990A-F5 $4.00 Touch Serial Number F50 MicroCan - Used as a personal =
ID tag for gaining access to the house etc.

The interface for the 1 Wire could be done from either a PC, 68HC11, =
8051, Z180 basically anything with an I/O port.

X10
Unfortunately X10 devices are not available here in Australia 240VAC =
50Hz. Others wise this would make a great starting point for the HA =
system.

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Answer

If slew rate control and active pull = up where=20 applied then typically the cable run would be limited to = 300m.

The cable can be organised in a tree = arrangement=20 with branches controlled by nodes.

&nb= sp; &nbs= p; =20 |-------------- I/O ----------- EOL

Controller =20 ----------|

&n= bsp; &nb= sp; =20 |--------------|----------------I/O + TS -------- I/O ----------- = EOL

&n= bsp; &nb= sp; =20 | = =20 |---------------- I/O --------- I/O --------- EOL

&n= bsp; &nb= sp; =20 |

&n= bsp; &nb= sp; =20 |---------------- I/O -------- I/O ------- TS ------- I/O -------------- = EOL

I/O =3D This is a TO92 = shaped=20 device that can be either a 5V digital input or open collector output = rated at=20 20mA.

EOL =3D This is a TO92 shaped device with a = unique=20 serial number internally. This allows you to check if the cable run is = function=20 correctly.

TS =3D Temperature Sensor = in a TO92=20 Package.

The I/O, TS and EOL use two of there three legs to connected to the = bus the=20 third leg on the I/O is the actual I/O pin. The third leg on the EOL is = not=20 used. The third leg on the TS connects to en external 5V Power = supply.

You could not ask for anything simpler.

Typical Prices area as follows

DS2407 $5.00 Each = I/O=20 Device

DS1820 $8.00 Each = Temperature=20 Sensor

DS2401 $2.50 Each Serial=20 number

DS1990A-F5 $4.00 Touch Serial Number F50 MicroCan - Used as a = personal ID tag=20 for gaining access to the house etc.

The interface for the 1 Wire could be done from either a PC, = 68HC11, 8051,=20 Z180 basically anything with an I/O port.

X10

Unfortunately X10 devices are not available here in Australia = 240VAC 50Hz.=20 Others wise this would make a great starting point for the HA = system.

More food for thought

Neil.