TI Launchpad 8 bit FFT Spectrum Analyzer
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README.md

lp_8bitfft

TI Launchpad 8 bit FFT Spectrum Analyzer

Description:

This audio spectrum analyzer is a project for the TI Launchpad (Value Line) w/ CircuitCo's Educational BoosterPack. It is microphone based and require minimal external components. Efforts were made to maximize the use of device / features from the Educational BoosterPack.

ADC10, TimerA interrupt LPM wakeup, TimerA PWM like output, button use, integer arithmatic are used and demonstrated.

Features:

. 8 bit integer FFT
. 32 samples at 500Hz separation
. shows 16 amplitudes of 250Hz, 500Hz, 750Hz,....... 5.75Khz, 6.75Khz, 7.75Khz non-linear
. partial logarithm map to show amplitudes, limited as resolution has been reduced for 8 bit FFT
. LM358 two stage mic pre-amp at 100x 100x gain (can be improve vastly w/ better op-amps)
. utilize Educational BoosterPack; mic for input, potentiometer for pre-amp biasing
. draws power from launchpad
. square signal generator from TA0.1 toggling, good for initial testing
. TA0.1 ouput to P1.6 (io) or P2.6 (buzzer)
. P1.3 button used to cycle thru 1. no ouput, 2. P1.6 signal, 3. P2.6 buzzer
* in mode 2 and 3, both band and amplitude scales are linear
* in mode 3, signals are distorted after passing buzzer and condensor mic, especially in low frequency


      TI LaunchPad + Educational BoosterPack
     ---------------
 /|\|            XIN|-
  | |               |
  --|RST        XOUT|-
    |               |
    |           P1.4|<-- ADC4
    |               |
    |           P1.6|--> TA0.1


. LM358 Dual Op-Amp, GBW @0.7Mhz, each stage @x100 gain, bandwidth is 7Khz

                    +------------------------------+
                   _|.                             |
                   ___ 10uF                        |
                  + |   ---------------            |
                    +-1|----.       Vcc|8          |
                    |. |    ^      .---|7--+-------|-----o (A)
               100k| | |   / \     ^   |   |.      |.
                   |_| |  /__+\   / \  |  | |100k | |1k
      0.1u          |  |   | |   /__+\ |  |_|     |_|
(B) o--||--[ 1k  ]--+-2|---+ |    | |  |   |       |
(C) o-------------+---3|-----+    +-|--|6--+-------+
                  |   4|Gnd         +--|5----+
                  |     ---------------      |
                  |                          |
                  +--------------------------+

(A) to P1.4 EduBoost Mic jumper middle pin
(B) to Condenser Mic, EduBoost Mic Jumper top pin 
(C) to Potentiometer, EduBooster Potentiometer Jumper top pin
(+) connect Gnd + Vcc to Launchpad

Chris Chung June 2013 . init release

code provided as is, no warranty

you cannot use code for commercial purpose w/o my permission nice if you give credit, mention my site if you adopt much of my code