Hi, just looking for advice on a ds18b20 network, i have about 10 points im measuring each one has 3 sensors to get an average and show up and bad sensors, im using a method where each group of 3 sensors is ona digital pin and i call a command from node red raspberry pi to create the onewire and read and retuen data amd all works well as long as i stagger requests as can be expected, if interested one of my other posts shows the code for this, ive done it this way as i want to add and remove sensors or relays to digital pins without recoding the arduino.
My quaestion is about parasite power, would connecting all my + and - power wires to ground and having a 5v conection passing through a 4k7 resitor and connecting to the signal wire before it connects to the digital pin work well? Im in the process of connection and the workng is a complete mess and this would simplify and hopefully stabily would be better.
In the parasite power setup, you usually have a pull-up resistor (commonly around 4.7k ohms) between the VCC and data lines. The data line is pulled high by this resistor when it's not actively being driven low by a sensor. Connecting the VCC of all sensors together might not work as expected, as each sensor may not get enough power for accurate readings.
Only one sensor will be polled for data at a time, to be honest im struggling to understand how parasitic power works, my normal configuration is all negative 5v connected and all positive 5v connected with a 4k7 ohm resistance for each signal wire to pull it up due to the fact each signal wire is going to a different digital pin. Would parastic offer any better stabilty, only the active pin been polled for data is using power and any one time i think?
Almost certainly not. Nobody has ever come up with a good reason for using parasite power in the face of the grief for which it is notorious, and if you insist on using it, you will deserve all the grief you get.
I don't think you have a power problem.
Thank you, no i dont have a power problem, my sensors were unreliable at returning serial data when i was trying to call them all at once, now i have staggered the calls they are much more reliable, the only problem i have at the moment is how to keep the wiring manageable and everything terminates into one box and its quite messy.
I was just curious about parastic power, basically if it was useful or stable.