HI,
I use arduino to read a sensor (Antenna) value. we measure from a oscilloscope that antenna values. we got that the maximum value or peak value is some what 200 mV. But the analog read value gives 1023 read as peak. when i give 5 v to the that pin then it gives 1023 also. what is the problem. Can you help me?
Here i attached the arduino readings and the screen shot of the oscilloscope.
230V-1A - 0cm .txt (9.68 KB)
hi,
can you help me with this?
this signal is 50 Hz.
I use arduino to read a sensor (Antenna) value. we measure from a oscilloscope that antenna values. we got that the maximum value or peak value is some what 200 mV. But the analog read value gives 1023 read as peak. when i give 5 v to the that pin then it gives 1023 also. what is the problem. Can you help me?
Here i attached the arduino readings and the screen shot of the oscilloscope.
230V-1A - 0cm .txt (9.68 KB)
But the analog read value gives 1023 read as peak. when i give 5 v to the that pin then it gives 1023 also. what is the problem.
The problem is how you have wired it up. You need to post a schematic.
moderator:
please do not crosspost (asking the same question more than once)
please do not use other persons thread for your questions.
thank you.
Achira:
...
this signal is 50 Hz.
as peak. when i give 5 v to the that pin then it gives 1023 also. what is the problem. Can you help me?
Here i attached the arduino readings and the screen shot of the oscilloscope.
http://www.eetimes.com/author.asp?section_id=36&doc_id=1319495
You are misunderstanding what you are measuring w/ the o'scope.
You are simply measuring the power-line 50Hz inducement into the open wire connected to a probe with a 1 megaOhm typical AC/DC impedance.
W/Arduino, the AC hum inducement will be based upon the ADC characteristic DC impedance of approx 100 megaOhm. But, Atmel indicates that a DC impedance of 10 kiloOhm is desired for accurate ADC measurements:
(23.6.1) Page 257 states: "The ADC is optimized for analog signals with an output impedance of approximately 10 k? or less. If such a source is used, the sampling time will be negligible. "
Then there is the whole issue that on the Arduino, you can only measure positive voltage, so the input signal must " ride" a bias voltage to allow the +/- nature of the AC to be DC offset.
So, in American lingo, you are comparing Apples to Oranges.
Ray
Your problem would be more obvious if you attached a speaker instead of an oscilloscope. Mains hum is very distinctive 
