Raspberry Pi Forums

Hi,

Just a quick question about the voltage of the 1820 temperature probes. I read that you should only use 3.3v with the GPIO pins on the PI, but most of the wiring diagrams for the 1820 are connected to the 5 volt pin.
As I am going to be using between 7 and 10 probes ( about a 10 meter run, evenly spaced ) should I be use 3.3 or 5 volts.

Any comments or advice?

Thanks
Leo

leodh wrote:
Any comments or advice?

Thanks
Leo

Read the datasheet from the manufacturer. Follow their recommendations.

Hi Leo,

leodh wrote:As I am going to be using between 7 and 10 probes ( about a 10 meter run, evenly spaced ) should I be use 3.3 or 5 volts.

Any comments or advice?

Since you have several probes, try to avoid parasite power mode (this depends also on conversion frequency, etc). You can use 5V supply voltage, which offers some more margin. Additionally, you could get better results by decreasing the data line pull-up resistor (value mostly listed as 4k7) to 3k3 or even slightly more.


Best wishes, Ivan Zilic.