DS18B20 and 28 Pin Project Board

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pilko

Senior Member
Can I use a DS18B20 temp sensor with an Axe 20, 28 pin project board.
The project board has the 8-10k pulldown resistors on board in a resistor network.
Am I correct in saying that the only way I can use this combination, is to cut the PCB trace between one of the 10k resistors and 0V
 
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westaust55

Moderator
DS18B20 and AXE020

Yes, you need to remove the pull-down resistor.

The DS18B20 requires a 4k7 pull-up resistor from the data line to +V (5V).
If you do a check with a multimeter you should be able to work out which end of the SIL resistor module is the common. Then consider cutting away just the resistor at the opposite end and use that PICAXE input (0 or 7?) which has thus been disconnected. Would recommend to try and cut the resistor rather than cutting tracks on the AXE020 board.
 
B

BeanieBots

Moderator
If this is for an actual application, then you should remove the 10k pull-down as Westaust describes.
However, if it's just to 'play' or demo the DS18B20, then you can get away with using a lower value pull-up with the 10k pull-down still in place.

Using a 1k8 pull-up with a 10k pull-down still in place will work.
However, you might experience a small amount of self heating depending on how often the DS18B20 is read.
 
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