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Author Topic: Temperature Sensor behaves strangely  (Read 487 times)
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Dear all,
i have the configuration as shown in the attachment.
i connected an external 5v to the GSM shield to prevent short burst.  For my temperature sensors, i tested with TMP36 and LM35 (they are powered by a separated power supply; A 220AC to 4.9DC), they give me the same problem which is the analogRead() returns a random number, of which i see 1023 and 0 coming out quite a lot.  Is there something wrong with the hardware connection?  Please help me a little bit.  Thank you in advance!

Regards,


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Guys!  Now the problem shall reduce to the voltage supplied to the temperature sensor, when i am powering my LM35 sensor from the 5v Supply on the Arduino UNO, everything works fine.  But if i am powering it from a separated power supply, things gone wrong terribly?  Anyone got a clue for this?

Regards,
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Do you have the grounds connected between the arduino board and the external PSU?
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I believe no sir!  Which ground on the arduino shall i connect smiley-yell

It may be the cause of it!  Thank you  for replying! smiley-mr-green
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I believe no sir!  Which ground on the arduino shall i connect smiley-yell

It may be the cause of it!  Thank you  for replying! smiley-mr-green
Any one of the ground pins on the arduino will do. An UNO () has 3 of them (marked GND), 2 next to the 5Vand one the other side next to AREF. Your board may be different but you should get the idea
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Problem solved! Thank you very much for your help! smiley
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