Problems with Ds18b20

Hi!

I'm using 12 ds18b20 sensors, all connected to the same port (I didn't use the parasite configuration)
When I am reading the sensor values, on some cards it is not possible to read the values ​​when I have more than 8 sensors (even though the code is configured for these readings).

It happens that on some boards the sensors are read correctly without problems, but on some not.

Has anyone had any problems with readings from many ds18b20 sensors?

Thanks in advance.

I believe that nasty thing called capacitance is getting you. The longer the wire the worse the problem. Probably the first thing to try would be to add a pull up resistor on the pin, start with something in the 4.7K range and go from there. If that fails try splitting it on several pins. This is only a guess to help as I cannot see the signals.

Maxim GUIDELINES FOR RELIABLE LONG LINE 1-WIRE NETWORKS - Guidelines for Reliable Long Line 1-Wire - Maxim Integrated

gilshultz:
I believe that nasty thing called capacitance is getting you. The longer the wire the worse the problem. Probably the first thing to try would be to add a pull up resistor on the pin, start with something in the 4.7K range and go from there. If that fails try splitting it on several pins. This is only a guess to help as I cannot see the signals.

Thanks for the help gilshultz!!