my son and i started a project in spring. It should be a home made bbq thermometer with 4 probes and android app
It seems to be no problem and my son made a app which is realy more than we planned. But when we tried the thermometers in action the measurements aren´t OK.
if only one sensor changes all other react to it... I´m not sure what´s the problem ? Maybe the circuit ? maybe the current ?
The LCD Backlight is on/off with some mercury switch to save some energy while BT using.
Please post a proper schematic (those Fritzings are too unreadable), and code is best posted inline rather than as attachment (now I'm on my Windows laptop and it doesn't even know how to open it) - between code tags for readability.
Wawa:
Try reading the analogue inputs twice (the second reading will be used).
durchschnitt1 = analogRead(ntc1); // dummy read
durchschnitt1 = analogRead(ntc1); // real reading
durchschnitt2 = analogRead(ntc2); // dummy read
durchschnitt2 = analogRead(ntc2); // real reading
etc.
Leo..
That's not the issue, those are 10k resistors in the thermistor dividers so the source impedance is low enough.
What is probably happening is there's a poor connection somewhere on the supply or ground between Arduino
and the dividers, so they don't get the full supply voltage and the changing currents causes a variation in voltage for the others.
The power to the BT module should go direct from the Arduino, not share wiring with the sensors.
