Martin Simpson
FFT using CMSIS for non mbed-os for smaller capacity chips with DAC output e.g. F303K8 to display FFT to an Oscilloscope with example to send to MAX7219 LED Array
Dependencies: MAX7219 mbed-dsp mbed
Revision 0:6daa40cd81ec, committed 2018-04-13
- Comitter:
- martinsimpson
- Date:
- Fri Apr 13 09:22:26 2018 +0000
- Commit message:
- 1st commit
Changed in this revision
diff -r 000000000000 -r 6daa40cd81ec MAX7219.lib --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MAX7219.lib Fri Apr 13 09:22:26 2018 +0000 @@ -0,0 +1,1 @@ +http://os.mbed.com/teams/Maxim-Integrated/code/MAX7219/#b5e4379a3d90
diff -r 000000000000 -r 6daa40cd81ec main.cpp
--- /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;
+}
\ No newline at end of file
diff -r 000000000000 -r 6daa40cd81ec mbed-dsp.lib --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed-dsp.lib Fri Apr 13 09:22:26 2018 +0000 @@ -0,0 +1,1 @@ +https://developer.mbed.org/users/mbed_official/code/mbed-dsp/#3762170b6d4d
diff -r 000000000000 -r 6daa40cd81ec mbed.bld --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Fri Apr 13 09:22:26 2018 +0000 @@ -0,0 +1,1 @@ +https://os.mbed.com/users/mbed_official/code/mbed/builds/e7ca05fa8600 \ No newline at end of file