OK, here is not mention which FFT will be suitable to be used DIT OR DIF FFT?? what algorithms(radix)??
There is no convention as to how the results appear in the array. Here are things to watch for:This is not entirely true. If you were to sample a 1Hz signal for 1 Second at 1024 SPS, and do an FFT on the result, you should have a rather nice approximation of a delta function at 1Hz. Interpretation should be trivial.
1)On my chip Reference Manuall saise "Analog input voltage range: 0V to 3.3V". So i must amplified to max 3.3V ?1) If your other question is "do I need to amplify the signal", yes. You'll want it to be about 4-5V, with center at 2 or 2.5V
2) or whatever RAM you have.
3) Decide frequency buckets
4) Did you look at the source code that was in the link I posted above? You are doing the same thing, except to double the frequency (40kHz Sample Rate), and a different output device (LED Matrix).
Ok, then you have a 3.3v controller, so the input needs to be amplified to 0-3.3V, it cannot go below 0, or over 3.3V. If you power the input amp from 3.3V with a Rail to Rail Op amp, then you'll be fine. Too much gain will just cause the signal to clip rather than hurt the ADC/uC. Though a clipped signal will show false high frequencies after the FFT, so set it close to clipping with max input volume if you have a scope and signal generator.1)On my chip Reference Manuall saise "Analog input voltage range: 0V to 3.3V". So i must amplified to max 3.3V ?
4)That source code is write in HiTech C18 i think, so i cant view it.
My uc is programable with an Arduino like IDE. Its the same software modify to suport PIC32.
I finaly decided abouth the LED matrix and the programabile board: it will be 26X64 led matrix powerd by an chipKIT MAX 32 http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,892,894&Prod=CHIPKIT-MAX32
If I found a good amp to work properly at 3,3 vYou won't need the Zener if you power your amp from the 3.3V source.
MCP6024If I found a good amp to work properly at 3,3 v
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