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Topic: Temperature Sensor behaves strangely (Read 538 times) previous topic - next topic

camac

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,

camac

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,

Riva

Do you have the grounds connected between the arduino board and the external PSU?

camac

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:

Riva


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

camac

Problem solved! Thank you very much for your help! :)

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