不韋 呂 / Mbed 2 deprecated UIT2_FIR_LPF_Direct_Fixed

FIR filter using fixed point arithmetic operations for ST Nucleo F401RE.

Dependencies:   UITDSP_ADDA mbed

main.cpp@8:abd11816e480, 2015-11-16 (annotated)

Committer:
MikamiUitOpen
Date:
Mon Nov 16 02:23:51 2015 +0000
Revision:
8:abd11816e480
Parent:
6:bb0e5ef9befe 
9

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:da34e90f15a3 1 //--------------------------------------------------------------
MikamiUitOpen 0:da34e90f15a3 2 // FIR フィルタ，基本的な構造, 固定小数点演算を使う
MikamiUitOpen 0:da34e90f15a3 3 // Analog Input : A0
MikamiUitOpen 0:da34e90f15a3 4 // Analog Output: MCP4922 using SPI
MikamiUitOpen 8:abd11816e480 5 // 2015/11/16, Copyright (c) 2015 MIKAMI, Naoki
MikamiUitOpen 0:da34e90f15a3 6 //--------------------------------------------------------------
MikamiUitOpen 0:da34e90f15a3 7
MikamiUitOpen 8:abd11816e480 8 #include "ADC_BuiltIn.hpp" // for ADC not using interrupt
MikamiUitOpen 8:abd11816e480 9 #include "DAC_MCP4921.hpp" // for DAC MCP4921, MCP4922
MikamiUitOpen 0:da34e90f15a3 10 #include "Coefficients_200_LPF_Fixed.hpp"
MikamiUitOpen 0:da34e90f15a3 11
MikamiUitOpen 0:da34e90f15a3 12 using namespace Mikami;
MikamiUitOpen 0:da34e90f15a3 13
MikamiUitOpen 0:da34e90f15a3 14 const int FS_ = 12000; // Sampling frequency: 12 kHz
MikamiUitOpen 4:a4b03c9a371c 15 const uint16_t OFFSET = 2047; // Correspond to "0"
MikamiUitOpen 8:abd11816e480 16 ADC_BuiltIn adc_(A0, FS_); // for AD
MikamiUitOpen 8:abd11816e480 17 DAC_MCP4921 myDac_; // for DA
MikamiUitOpen 0:da34e90f15a3 18
MikamiUitOpen 0:da34e90f15a3 19 int main()
MikamiUitOpen 0:da34e90f15a3 20 {
MikamiUitOpen 6:bb0e5ef9befe 21 myDac_.ScfClockTim3(500000); // cutoff frequency: 5 kHz
MikamiUitOpen 0:da34e90f15a3 22
MikamiUitOpen 0:da34e90f15a3 23 int16_t xn[ORDER_+1];
MikamiUitOpen 0:da34e90f15a3 24 for (int n=0; n<=ORDER_; n++)
MikamiUitOpen 0:da34e90f15a3 25 xn[n] = 0;
MikamiUitOpen 0:da34e90f15a3 26
MikamiUitOpen 0:da34e90f15a3 27 while (true)
MikamiUitOpen 0:da34e90f15a3 28 {
MikamiUitOpen 4:a4b03c9a371c 29 xn[0] = adc_.Read_u16() - OFFSET; // Read from A0
MikamiUitOpen 0:da34e90f15a3 30 //-----------------------------------------------
MikamiUitOpen 0:da34e90f15a3 31
MikamiUitOpen 0:da34e90f15a3 32 int32_t yn = 0;
MikamiUitOpen 0:da34e90f15a3 33 for (int k=0; k<=ORDER_; k++)
MikamiUitOpen 0:da34e90f15a3 34 yn = yn + hm_[k]*xn[k];
MikamiUitOpen 0:da34e90f15a3 35
MikamiUitOpen 0:da34e90f15a3 36 for (int k=ORDER_; k>0; k--)
MikamiUitOpen 0:da34e90f15a3 37 xn[k] = xn[k-1]; // move input signals
MikamiUitOpen 0:da34e90f15a3 38
MikamiUitOpen 4:a4b03c9a371c 39 // rounding and devide by 32768 + DC offset
MikamiUitOpen 8:abd11816e480 40 uint16_t yOut = ((yn + 0x4000) >> 15) + OFFSET;
MikamiUitOpen 0:da34e90f15a3 41 //-----------------------------------------------
MikamiUitOpen 4:a4b03c9a371c 42 myDac_.Write(yOut); // Write to DAC
MikamiUitOpen 0:da34e90f15a3 43 }
MikamiUitOpen 0:da34e90f15a3 44 }