Minor updates to get the FFT sample running again.

Although it currently calculates frequencies that are twice the
signal frequency, but that might be a simple fix once somebody
can look into the audio configuration.

Author: microbit-carlos

CMakeLists.txt

@@ -50,7 +50,7 @@ RECURSIVE_FIND_FILE(LIB_ARCHIVE_FILES "${CMAKE_CURRENT_LIST_DIR}/lib" "*.a")
 
 set(CMAKE_SYSTEM_PROCESSOR "armv7-m" PARENT_SCOPE)
 
-set(ROOT "${CMAKE_CURRENT_LIST_DIR}/CMSIS_5/")
+set(ROOT "${CMAKE_CURRENT_LIST_DIR}/CMSIS_5")
 list(APPEND INCLUDE_DIRS "${ROOT}/CMSIS/Core/Include/")
 
 

samples/fft_example.cpp

@@ -2,7 +2,6 @@
 #include "CodalDmesg.h"
 #include "MicroBitAudioProcessor.h"
 #include "StreamNormalizer.h"
-#include "Tests.h"
 
 static NRF52ADCChannel *mic = NULL;
 static StreamNormalizer *processor = NULL;
@@ -14,8 +13,9 @@ MicroBit uBit;
   * fft_test function - creates an example MicroBitAudioProcessor and then queries it for results.
   * Currently configured to use 1024 samples with 8bit signed data.
   */
-void fft_test(){
+void fft_test() {
     uBit.display.print("L");
+/*
      if (mic == NULL){
         mic = uBit.adc.getChannel(uBit.io.microphone);
         mic->setGain(7,0);
@@ -29,13 +29,17 @@ void fft_test(){
 
     uBit.io.runmic.setDigitalValue(1);
     uBit.io.runmic.setHighDrive(true);
+*/
 
+    // Code above commented out was from the original example, which can
+    // probably be replaced with this single line, but we need to double check
+    // the configuration because the fft calculation results are twice the frequency
+    fft = new MicroBitAudioProcessor(*uBit.audio.splitter->createChannel());
 
     //Start fft running
     fft->startRecording();
 
-
-    while(1){
+    while (1){
         //TODO - de-noise : if last X samples are same - display ect.
         //The output values depend on the input type (DATASTREAM_FORMAT_8BIT_SIGNED) and the size
         //of the FFT - which is changed using the 'AUDIO_SAMPLES_NUMBER' in MicroBitAudioProcessor.h
@@ -64,13 +68,7 @@ void fft_test(){
     }
 }
 
-
-
-int 
-main()
-{
-
+int main() {
     uBit.init();
     fft_test();
-    
-}
+}

source/MicroBitAudioProcessor.cpp

@@ -55,8 +55,6 @@ MicroBitAudioProcessor::~MicroBitAudioProcessor()
 
 int MicroBitAudioProcessor::pullRequest()
 {
-
-    int s;
     int result;
 
     auto mic_samples = audiostream.pull();
@@ -99,9 +97,9 @@ int MicroBitAudioProcessor::pullRequest()
             //DMESG("Before FFT: %d", (int)a);
             //DMESG("After FFT: %d (%d)", (int)b, (int)(b - a));
 
-            uint32_t freq = ((uint32_t)MIC_SAMPLE_RATE / AUDIO_SAMPLES_NUMBER) * (index + 1);
+            lastFreq = ((uint32_t)MIC_SAMPLE_RATE / AUDIO_SAMPLES_NUMBER) * (index + 1);
             DMESG("Freq: %d (max: %d.%d, Index: %d)",
-                  freq,
+                  lastFreq,
                   (int)maxValue,
                   ((int)(maxValue * 100) % 100),
                   index);