Hi, I just got my spark core and have tried connecting an LM35 sensor to it, but am stumped with the results. Tinker app gives me a reading of cca 492, and if I convert this to voltage, it should be 0,39 V, right? If I measure with the voltmeter (measuring between A0 and GND), I get 0,29 V. I al…

Keep the Spark Core ABOVE the temp sensor or the heat it puts off will cause your temp readings to be high due to it running at 100+ Degrees F.

Not quite sure by what you mean above the sensor, it’s a bit away on the breadboard, however spark core is quite cold to the touch at the moment. Also, the main problem seems to be with the analogRead measurement which differs from the voltage measured with the voltmeter.

I can’t help with your Analog reading issue but just wanted to warn ya about the warm temp of the Spark Core will throw off your temp readings unless the Spark Core is placed above your temp sensor so all the heat it emits will rise up and not affect your temp readings. Good luck.

clarity, there were issues with the A/D conversions that are now fixed but I am not sure they have been updated in the Web IDE. I will check and update this post. UPDATE: Yup, the update has not been pushed to the web IDE yet but is available for users doing local compiling of the code.

Hi @clarity @peekay123 is right about the ADC code in the webIDE (the “Build” button on the website) being a little bit behind the “master” branch that can try out if you compile your code on your local computer. The “master” branch will move to the webIDE when Spark has fully tested it. Using th…

bko, regarding the 3.3* pin, I also found that I had problems with some devices whose lower supply tolerance is 3.3v such as a DHT22 temperature/humidity sensor. I had to use a separate 3.3v supply. @clarity , from the LM35 specs, I noticed that it operates from 4 to 30V so the 3.3v supply will no…

Hi, I’m trying run a lm35 but the temperatures are divergents. I’m using this code: I tried with 1024, 4095 and 5000 tthe pin vs = VIN for sample now is 25º but the sensor read 35 if I insert it on a freezer the minimum temperature is +22 int analogvalue = 0; double tempC = 0; void setup() { …

@rbbahia , I think you got your answer here already. [image] lm35 spark read incorrect temperature General Are you sure you’re using a 3V3 sensor? Since the standard LM35 requires a minimum if 4V supply …

I am using LM35 and I am getting a bad result. The temp reading is ok but when I turn on an external LED with Blynk app (or another method) the temp reading increase to 1 or 2 C (10 or 20mV). What is happening?

Hi @jonamleonel It sounds like your sensor is too close to your Photon device since when you turn on the LED, more current is needed from the Photon board and it heats up a bit more. Can you try extending the wiring so that the sensor is say 10cm or 4" away from everything else? I have found that…

Newbie - problem reading LM35 sensor - voltage measured differs

Troubleshooting

ScruffR April 27, 2015, 5:06am 9

@rbbahia, I think you got your answer here already.

Please, don't double post!

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Newbie - problem reading LM35 sensor - voltage measured differs

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