Have this setup with a 16F18887 and a DS18B20 temp probe,
Setup is working fine over 50 cm wire, but when i encrease to around 10m
i get no reading,
Have an old setup with a 16F690 same wire, and that works fine.
Use a 5 k pull up near the sensor,
Have also tried to place the pull up near PIC,

What can i do to get a reading ?

And Spinaker, no need to say not again,

Rgds
Sten

 

Read pages 40-41 of an937.

 

AN937 here:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/937
More info here:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/148

You'll have to do some noodling on it.
Good luck!

 

Have you considered wireless?

 

AN937 here:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/937
More info here:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/148

You'll have to do some noodling on it.
Good luck!

Those 2 link are not working, dead.
Now point on wireless, to much interference, that is why i switched to wire,

Page 40-41 , all i have found to a AN937 datasheet has only 16 pages

 

Those 2 link are not working, dead.
Now point on wireless, to much interference, that is why i switched to wire,

Page 40-41 , all i have found to a AN937 datasheet has only 16 pages

I went directly to maximintegrated.com and none of their ap-notes come up. Server error? Try it again later, maybe.
BTW, some searches return Microchip's AN937. Not the same.

Here's the link to the ap-note page directory.
https://www.maximintegrated.com/en/...the contact range of iButtons&_charset_=UTF-8

 

Dont see that have to do with reading from a ds18b20 sensor.
Btw reading is stillnok up to 0.5 m. But over 5-7 i get problems.(16f18887)

Same sensor reads ok with 16f690.

 

Have been playing a lot, and searched all over.
On my desk i have the 16F18877 and a DS18B20
Use a 4,7k pull up near the PIC.
That works like perfect.

Want to extend the wire from PIC to DS18B20.
Have a CAT5E cable 10 meter. Use a Pair for +5v and GND, and another pair for 1-Wire and GND,
When using that, i get the sensor i precent, but no readings, Then i try a smaller resistor, and place it near the sensor,
4k5 3K0 1k5 , and R750, but nothing gives me readings,

Have my "old" setup with a 16F1509 where i just use an old loudspeaker wire, and that works with no problems at 10 meters.
There i just placed the 4k7 resistor near the sensor,

Could someone explain how to get it to work ?
Do i need changes to timing ?
Do i need some CAPS or other thing ?
Can i build an extender or ? and how ?

It's driving me mad.

Rgds

 

Generally, to make longer distance work, you want to use lower frequency.

How are you implementing 1-wire? Does PIC have hardware module to do 1-wire? Is it software implementation?

 

I think it works now. I just took one twisted pair for signal. Before i use one for signal and the other to ground.
Right now it runs perfect but 10m wire is not rolled out yet. Just connected.

Yes PIC use software.

 

Guidelines for Reliable Long Line 1-Wire Networks
https://www.maximintegrated.com/en/app-notes/index.mvp/id/148