Multiplexer causing data corruption?????

Other Miscellaneous
1

Hey all, I’m really stumped.

I’ve been trying to make a temperature sensor to put in my refrigerator. I’m using a TMP36 temp sensor, sending data to an Adafruit Feather Huzzah 8266 and thru that to AdafruitIO. Since I also want to monitor battery voltage and the Huzzah only has one ADC, I’ve added the SparkFun Multiplexer Breakout - 8 Channel (74HC4051) to send alternately the battery voltage and the temperature voltage.

I’ve managed to get it working with only the TMP36 and no MUX, but when I add the MUX, the temperature voltage no longer drops when I put it in the fridge. Since it works without the MUX, it seems to point to the MUX as the problem, but I can’t think of why that would be. When I try it with the multiplexer, I DO get realistic values from the battery voltage, but not the temperature.

Can anyone suggest what is wrong?

2

Are you sure you’ve selected the correct port on the MUX? If the temp isn’t changing at all, I’d suspect your selecting the wrong port on the MUX.