- Joined Aug 8, 2015
I have a working temperature sensor that is connected correctly and working but there is a simple issue that still bugs me. The sensor has 4 pins namely VCC, gnd, humidity(not important for topic) and a temperature pin. The temperature is measured as a function of resistance. When the temperature changes, the resistance of the sensor changes as well. Before i read the data sheet carefully i connected the pin directly to the ADC and it gave a maximum reading of 1023 irrespective of temperature. I understood this as the voltage drop over the temperature sensor to be the input voltage of 5V as it is the only resistor in the circuit. This must mean the pin leaving the sensor would need to be attached at a point before the temperature sensitive resistance inside the sensor. What puzzles me is that to solve the problem, i connected a resistor from the temperature output pin to ground and the the output pin to the ADC. This solved the problem on the concept of series resistors being voltage dividers but if my first assumption was correct then shouldn't that mean that the resistor that i added was in fact connected in parallel?