Diff: main.cpp

Revision:

0:6daa40cd81ec

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Apr 13 09:22:26 2018 +0000
@@ -0,0 +1,123 @@
+#include "mbed.h"
+/*ADAFruit 8x8 LED Array driver chip SPI */
+#include "max7219.h"
+/* Include arm_math.h mathematic functions */
+#include "arm_math.h"
+/* Include mbed-dsp libraries */
+#include "arm_common_tables.h"
+#include "arm_const_structs.h"
+#include "math_helper.h"
+
+/* FFT settings */
+#define SAMPLES                 512             /* 256 real party and 256 imaginary parts */
+#define FFT_SIZE                SAMPLES / 2     /* FFT size is always the same size as we have samples, so 256 in our case */
+
+/* Global variables */
+float32_t Input[SAMPLES];
+float32_t sampler[SAMPLES]={0};
+float32_t Output[FFT_SIZE];
+bool      trig=0;
+
+/*Function Prototypes */
+uint16_t convert_bar(uint16_t);
+void sample();
+
+/* MBED class APIs */
+DigitalOut myled(LED1);
+AnalogIn   myADC(A1);
+AnalogOut  myDAC(A3);
+Ticker     timer;
+
+/* Other class APIs */
+Max7219 max7219(D11, D12, D13, D10);//SPI0_MOSI, SPI0_MISO, SPI0_SCK, SPI0_SS);
+
+void sample(){
+    trig=1;
+    }
+    
+int main() {
+
+    uint8_t  array[]={0x1F,0x14,0x10,0x00,0x1F,0x14,0x10,0x00,0x10,0x1F,0x10}; //text 'FFT'
+    uint16_t array_size=sizeof(array);
+    int16_t  i,j;
+    float maxValue;            // Max FFT value is stored here
+    uint32_t maxIndex;         // Index in Output array where max value is
+    
+    printf("FFT Example using 32F303K8 DAC output\r\n");
+    
+    max7219_configuration_t cfg = {
+         .device_number = 1,
+         .decode_mode = 0,
+         .intensity = Max7219::MAX7219_INTENSITY_4,
+         .scan_limit = Max7219::MAX7219_SCAN_8
+     };
+
+     max7219.init_device(cfg);
+     max7219.enable_device(1);
+     max7219.set_display_test();
+     max7219.clear_display_test();
+     max7219.display_all_off();
+   
+     for(j=-8;j<=array_size;j++){
+        for(i=1;i<=array_size;i++){
+            max7219.write_digit(1,9-i+j,array[i-1]);
+        }
+        wait_ms(100);
+        max7219.display_all_off();
+     }
+
+    //arm_cfft_instance_f32 S;   // ARM CFFT module
+    //float maxValue;            // Max FFT value is stored here
+    //uint32_t maxIndex;         // Index in Output array where max value is
+    
+    while(1) {
+            timer.attach_us(&sample,30); //30us 30,30 250KHz sampling rate ********
+
+            for (i = 0; i < SAMPLES; i += 2) {
+                while (trig==0){}
+                trig=0;  
+                Input[i] = myADC.read() - 0.5f; //Real part NB removing DC offset
+                Input[i + 1] = 0;               //Imaginary Part set to zero
+            }
+            timer.detach();
+            // Init the Complex FFT module, intFlag = 0, doBitReverse = 1
+            // NB using predefined arm_cfft_sR_f32_lenXXX, in this case XXX is 256
+            arm_cfft_f32(&arm_cfft_sR_f32_len256, Input, 0, 1);
+
+            // Complex Magniture Module put results into Output(Half size of the Input)
+            arm_cmplx_mag_f32(Input, Output, FFT_SIZE);
+        
+        Output[0]=0;
+        
+        
+            //Calculates maxValue and returns corresponding value
+            arm_max_f32(Output, FFT_SIZE, &maxValue, &maxIndex);
+            
+        
+            myDAC=1.0f; //SYNC here!! for Oscillscope at max DAC output for triggering purposes
+            wait_us(20);//All FFT values will be lower since max scaling is 0.9 as below
+            myDAC=0.0f;//set trigger level on oscilloscope between 0.9 to 1.0 (*3.3Volts) i.e. 3.0 to 3.3Volts
+        
+            for (i=2; i<FFT_SIZE/2 ; i++){
+                myDAC=(Output[i]/maxValue)*0.9f; // All Values scaled to 0.0 to 0.9 for output to DAC
+            //    if (Output[i]>0.2){printf("%d %f\r\n",i,(Output[i]/maxValue)*0.9f);}
+                wait_us(10);
+            }
+            myDAC=0.0f;
+
+            for (i=0; i<9;i++){
+                max7219.write_digit(1,9-i,convert_bar((uint16_t)(Output[i*16]*2.9f)));//  5.8f
+            }
+        }
+}
+
+// Will take a number (numVal) 0 to 255 and return (converted) the next (lower) 2^n-1 value
+// to light up all LEDS as a bar graph representation
+uint16_t convert_bar(uint16_t numVal){
+    if (numVal>255){return 0;} 
+    uint16_t converted = 0;
+        for (uint16_t i=1; i<=256 ; i*=2){
+            if ((numVal/(i)) >= 1){converted = (i-1);}
+            }
+    return converted;   
+}
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