不韋 呂 / Mbed 2 deprecated UIT2_SinGenerator_IirFilter

Sin generator using 2nd-ordered IIR filter for ST Nucleo F401RE.

Dependencies:   UIT_ADDA mbed

main.cpp@0:8edfedfcdd26, 2014-10-21 (annotated)

Committer:
MikamiUitOpen
Date:
Tue Oct 21 12:52:45 2014 +0000
Revision:
0:8edfedfcdd26
Child:
2:799a843be414
1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:8edfedfcdd26 1 //--------------------------------------------------------------
MikamiUitOpen 0:8edfedfcdd26 2 // Sin generator using IIR filter
MikamiUitOpen 0:8edfedfcdd26 3 // Analog Output: MCP4922 using SPI
MikamiUitOpen 0:8edfedfcdd26 4 // 2014/10/21, Copyright (c) 2014 MIKAMI, Naoki
MikamiUitOpen 0:8edfedfcdd26 5 //--------------------------------------------------------------
MikamiUitOpen 0:8edfedfcdd26 6
MikamiUitOpen 0:8edfedfcdd26 7 #include "mbed.h"
MikamiUitOpen 0:8edfedfcdd26 8
MikamiUitOpen 0:8edfedfcdd26 9 #include "ADC_Base.hpp" // for ADC not using interrupt
MikamiUitOpen 0:8edfedfcdd26 10 #include "DAC_MCP4922.hpp" // for DAC MCP4922
MikamiUitOpen 0:8edfedfcdd26 11 #include "ScfClockTim3.hpp" // for clock supplied to SCF
MikamiUitOpen 0:8edfedfcdd26 12
MikamiUitOpen 0:8edfedfcdd26 13 using namespace Mikami;
MikamiUitOpen 0:8edfedfcdd26 14
MikamiUitOpen 0:8edfedfcdd26 15 const int FS_ = 12000; // Sampling frequency: 12 kHz
MikamiUitOpen 0:8edfedfcdd26 16 ADC_Base adc_(A0, FS_); // for AD
MikamiUitOpen 0:8edfedfcdd26 17 DAC_MCP4922 myDac_(DAC_MCP4922::DAC_A); // for DA
MikamiUitOpen 0:8edfedfcdd26 18
MikamiUitOpen 0:8edfedfcdd26 19 int main()
MikamiUitOpen 0:8edfedfcdd26 20 {
MikamiUitOpen 0:8edfedfcdd26 21 const float PI2 = 6.283185f;
MikamiUitOpen 0:8edfedfcdd26 22 const float F0 = 440.0f;
MikamiUitOpen 0:8edfedfcdd26 23 const float A1 = 2.0f*cosf(PI2*F0/(float)FS_);
MikamiUitOpen 0:8edfedfcdd26 24 const float B1 = 0.8f*sinf(PI2*F0/(float)FS_);
MikamiUitOpen 0:8edfedfcdd26 25
MikamiUitOpen 0:8edfedfcdd26 26 ScfClockTim3(500000); // cutoff frequency: 5 kHz
MikamiUitOpen 0:8edfedfcdd26 27
MikamiUitOpen 0:8edfedfcdd26 28 float yn1 = B1;
MikamiUitOpen 0:8edfedfcdd26 29 float yn2 = 0;
MikamiUitOpen 0:8edfedfcdd26 30
MikamiUitOpen 0:8edfedfcdd26 31 while (true)
MikamiUitOpen 0:8edfedfcdd26 32 {
MikamiUitOpen 0:8edfedfcdd26 33 float xn = adc_.Read(); // Dummy read for synchronization to Fs
MikamiUitOpen 0:8edfedfcdd26 34 //-----------------------------------------------
MikamiUitOpen 0:8edfedfcdd26 35
MikamiUitOpen 0:8edfedfcdd26 36 float yn = A1*yn1 - yn2; // y[n] = a1*y[n-1] - y[n-2]
MikamiUitOpen 0:8edfedfcdd26 37 yn2 = yn1; // y[n-2] <= y[n-1]
MikamiUitOpen 0:8edfedfcdd26 38 yn1 = yn; // y[n-1] <= y[n]
MikamiUitOpen 0:8edfedfcdd26 39
MikamiUitOpen 0:8edfedfcdd26 40 //-----------------------------------------------
MikamiUitOpen 0:8edfedfcdd26 41 myDac_.Write(yn); // Write to DAC
MikamiUitOpen 0:8edfedfcdd26 42 }
MikamiUitOpen 0:8edfedfcdd26 43 }