Serial Monitor Readings - TMP36

Other Hardware Sensors
1

Hello, I am a beginner and working my way through the Arduino projects book up to Project 03 - Love-o-Meter.

I have followed all instructions and my Serial Monitor readings are all over the place and showing minus temperatures. Other forums I've read from people that have problems with the readings at least show that their readings are consistent but I'm not sure where to start with fixing the problem.

When I touch the temperature TMP36 input nothing changes with the readings or any lights on the board. I've tried editing the code and changing the base temperature but I don't think its anything to do with the code.

I am using a MacBook Pro 2.3 GHz Intel Core i5 - and power is connected via USB port.

Is there something obvious here that I am doing wrong or is there an issue with the sensor?

Thank you in advance :slight_smile:

11:22:09.565 -> Sensor: 84, Volts: 0.41, degrees C: -8.98
11:22:09.601 -> Sensor: 67, Volts: 0.33, degrees C: -17.29
11:22:09.637 -> Sensor: 25, Volts: 0.12, degrees C: -37.79
11:22:09.705 -> Sensor: 57, Volts: 0.28, degrees C: -22.17
11:22:09.741 -> Sensor: 83, Volts: 0.41, degrees C: -9.47
11:22:09.774 -> Sensor: 49, Volts: 0.24, degrees C: -26.07
11:22:09.843 -> Sensor: 27, Volts: 0.13, degrees C: -36.82
11:22:09.881 -> Sensor: 76, Volts: 0.37, degrees C: -12.89
11:22:09.914 -> Sensor: 71, Volts: 0.35, degrees C: -15.33
11:22:09.982 -> Sensor: 26, Volts: 0.13, degrees C: -37.30
11:22:10.014 -> Sensor: 52, Volts: 0.25, degrees C: -24.61
11:22:10.051 -> Sensor: 84, Volts: 0.41, degrees C: -8.98
11:22:10.085 -> Sensor: 55, Volts: 0.27, degrees C: -23.14
11:22:10.159 -> Sensor: 26, Volts: 0.13, degrees C: -37.30
11:22:10.197 -> Sensor: 71, Volts: 0.35, degrees C: -15.33
11:22:10.231 -> Sensor: 75, Volts: 0.37, degrees C: -13.38
11:22:10.299 -> Sensor: 29, Volts: 0.14, degrees C: -35.84
11:22:10.336 -> Sensor: 48, Volts: 0.23, degrees C: -26.56
11:22:10.369 -> Sensor: 84, Volts: 0.41, degrees C: -8.98
11:22:10.438 -> Sensor: 60, Volts: 0.29, degrees C: -20.70
11:22:10.473 -> Sensor: 26, Volts: 0.13, degrees C: -37.30
11:22:10.508 -> Sensor: 66, Volts: 0.32, degrees C: -17.77
11:22:10.543 -> Sensor: 79, Volts: 0.39, degrees C: -11.43
11:22:10.615 -> Sensor: 34, Volts: 0.17, degrees C: -33.40
11:22:10.649 -> Sensor: 43, Volts: 0.21, degrees C: -29.00
11:22:10.682 -> Sensor: 84, Volts: 0.41, degrees C: -8.98
11:22:10.751 -> Sensor: 64, Volts: 0.31, degrees C: -18.75
11:22:10.788 -> Sensor: 30, Volts: 0.15, degrees C: -35.35
11:22:10.822 -> Sensor: 63, Volts: 0.31, degrees C: -19.24
11:22:10.889 -> Sensor: 81, Volts: 0.40, degrees C: -10.45
11:22:10.926 -> Sensor: 41, Volts: 0.20, degrees C: -29.98
11:22:10.959 -> Sensor: 42, Volts: 0.21, degrees C: -29.49
11:22:11.029 -> Sensor: 83, Volts: 0.41, degrees C: -9.47
11:22:11.066 -> Sensor: 69, Volts: 0.34, degrees C: -16.31
11:22:11.101 -> Sensor: 31, Volts: 0.15, degrees C: -34.86
11:22:11.134 -> Sensor: 59, Volts: 0.29, degrees C: -21.19
11:22:11.205 -> Sensor: 83, Volts: 0.41, degrees C: -9.47
11:22:11.242 -> Sensor: 53, Volts: 0.26, degrees C: -24.12
2

Your Arduino board is working; the Serial Monitor is working; the Arduino IDE environment is working. I think that you are doing allright.

Sometimes there is a broken wire or a wire is connected to the wrong input or the sensor is broken. If you can't fix, just move on. You can fix it once you know more about Arduino and electronics.

It seems that you are reading an open analog input (a input with nothing attached to it, or perhaps only a wire).
Do you have a multimeter ? Then you can measure the voltage of the pins of the sensor and check if that same voltage gets to the Arduino.