DS18s20

[MagnusP]

Hi,

Could anyone help me? I would like to connect several DS18S20 on one 1-wire net. I have a 1-wire USB connector (DS9490R) as the computer connection for the 1-wire net.
I have successfullt connected several parasite powered DS18S20 to the RJ11 connector of the USB Adaptor (Connected RJ11 PIN 3 to DQ(2) on DS18s20, and pin 4 to Vdd(3) and GND(1) on DS18s20). Works fine!

Now I want to supply +5v to the DS18s20 to make it non-parasitic powered. I tested to connect RJ11 pin 1 (Vdd) to pin 3 (Vdd) of the DS18s20, but then I couldn't get the ds18s20 to work?

What did I do wrong? Do I need to do anything else to power the ds18s20 from the RJ11 connector?

/Magnus

 

[misho]

What is corpus of DS18S20 ? TO-92? or u use 8-Pin 150mil SO

For TO-92 read this manuals
http://datasheets.maxim-ic.com/en/ds/DS18S20.pdf and for 1-Wire USB

http://datasheets.maxim-ic.com/en/ds/DS9490-DS9490R.pdf

Pin 1 on DS18S20 to pin 4 on DS9490R (GND)
Pin 2 on DS18S20 to pin 3 on DS9490R (DQ)
Pin 3 on DS18S20 to pin 1 on DS9490R (+5V)

Check Power supply !

 

[MagnusP]

What is corpus of DS18S20 ? TO-92? or u use 8-Pin 150mil

Pin 1 on DS18S20 to pin 4 on DS9490R (GND)
Pin 2 on DS18S20 to pin 3 on DS9490R (DQ)
Pin 3 on DS18S20 to pin 1 on DS9490R (+5V)
!

Its the TO-92!

The connection you show is what I did, didn't get that to work.

Pin 4 on the RJ11 is 1-Wire Return GND

If I connect pin 3 on DS18S20 to pin 1 (+5V) on DS9490R shouldn't Pin 2 GND Power Return also be involved?

 

[misho]

Strange ...

Try to supply DS18S20 with external +5V power supply (not impulse power supply) and see what is results ..

Pin 2 on DS9490R is without protection .. See http://pdfserv.maxim-ic.com/en/ds/DS9503.pdf .. this is protection of DS9490R.
I think no problem to use Pin 4 for GND, because have only 2 x 5 Om resistors ..

I think Power supply of PC is not filtered and u must use external !

 

[rdheiliger]

Measure the +5vdc on the sensor. I have found that the supply voltage can drop with little load. I use 18B20 with an external +5 supply, power injector and they work fine. When using an external supply, disconect the +5 from the 9490, but leave the common connected. Recheck and make sure you have not identified the 18S20 leads backwards, it is easy to do.

RD

 

[MagnusP]

I must have been tired when I connected the 18s20 to the net, I tested again and now it works with external power supply. Thanks to all of you!

 

[MagnusP]

As i worte, I got it working, however there is a small problem...

If I *hammer* the DS18S20 in parasite mode i get the correct temperature every time.

If I do the same thing in non-parasytic mode I get the temp most of the time, but every now and then a 85 degree value is presented.
The temperature conversion is completed according to the DS18S20 (I send TMTouchBit(session,&h1) to see if conversion is complete and it returns 1)

Any ideas on that?