How many DS18B20 can be connected to an ESP01 ?

[bennybubble]

Hi,

Can anyone tell me how many DS18B20's in parallel can/will be supported using only 1 pin on an ESP01 ?
In other words : how many will the software detect ?

-ben

[tozett]

may the SEARCH will be with you...

asked before here:
http://www.esp8266.nu/forum/viewtopic.p ... wire#p4175

[bennybubble]

Hi,

I did search before asking and you suggestion still did not answer the question

The question is not about how many sensors can be connected to one bus but how many does the software (ESPEASY) recognize and can be used ?

-ben

[costo]

Hi,

Can anyone tell me how many DS18B20's in parallel can/will be supported using only 1 pin on an ESP01 ?
In other words : how many will the software detect ?

-ben

Looking into the sourcecode of the Dallas plugin I see: byte devCount
so the number of Dallas devices is counted with a byte and because of that it is theoretically limited to 255 Dallas devices on one pin.

But (because of memory limitation ?) ESPEasy has reserved place for 12 devices only , so practically ESPEasy can support maximum 12 Dallas temperature sensors.

There is also the load_limitation of a ESP input and the load of the other devices on each other. This load consists of a resistive part and a capacitive part, which depends heavily on the length of the wires. Long wires means high capacitive load, means less devices.
Maybe if you use a line/bus driver I.C. you can overcome the load limitations of the hardware.

This all means you have to try it yourself, every situation is different because of the connecting wires to the sensors and the value of the resistor.

I hope this helps you a little bit.

[bennybubble]

Hi,

Thanks for the info, that is were I was looking for!

-ben

[chunter1]

Got 8 Sensors running on a 4m cable configured as 2-wire bus (just GND and Data, no Vcc wire used)

[andreo]

Got 8 Sensors running on a 4m cable configured as 2-wire bus (just GND and Data, no Vcc wire used)

How did you connect the sensors on the wires? Any schematic available?

[bennybubble]

Got 8 Sensors running on a 4m cable configured as 2-wire bus (just GND and Data, no Vcc wire used)

How did you connect the sensors on the wires? Any schematic available?

See http://www.tweaking4all.com/wp-content/ ... -power.jpg

-ben