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@4:a4b03c9a371c, 2014-10-30 (annotated)

Committer:
MikamiUitOpen
Date:
Thu Oct 30 02:56:13 2014 +0000
Revision:
4:a4b03c9a371c
Parent:
3:5c085430972b
Child:
6:bb0e5ef9befe
5

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 4:a4b03c9a371c 5 // 2014/10/29, Copyright (c) 2014 MIKAMI, Naoki
MikamiUitOpen 0:da34e90f15a3 6 //--------------------------------------------------------------
MikamiUitOpen 0:da34e90f15a3 7
MikamiUitOpen 0:da34e90f15a3 8 #include "mbed.h"
MikamiUitOpen 0:da34e90f15a3 9
MikamiUitOpen 0:da34e90f15a3 10 #include "ADC_Base.hpp" // for ADC not using interrupt
MikamiUitOpen 0:da34e90f15a3 11 #include "DAC_MCP4922.hpp" // for DAC MCP4922
MikamiUitOpen 0:da34e90f15a3 12 #include "ScfClockTim3.hpp" // for clock supplied to SCF
MikamiUitOpen 0:da34e90f15a3 13 #include "Coefficients_200_LPF_Fixed.hpp"
MikamiUitOpen 0:da34e90f15a3 14
MikamiUitOpen 0:da34e90f15a3 15 using namespace Mikami;
MikamiUitOpen 0:da34e90f15a3 16
MikamiUitOpen 0:da34e90f15a3 17 const int FS_ = 12000; // Sampling frequency: 12 kHz
MikamiUitOpen 4:a4b03c9a371c 18 const uint16_t OFFSET = 2047; // Correspond to "0"
MikamiUitOpen 0:da34e90f15a3 19 ADC_Base adc_(A0, FS_); // for AD
MikamiUitOpen 0:da34e90f15a3 20 DAC_MCP4922 myDac_(DAC_MCP4922::DAC_A); // for DA
MikamiUitOpen 0:da34e90f15a3 21
MikamiUitOpen 0:da34e90f15a3 22 int main()
MikamiUitOpen 0:da34e90f15a3 23 {
MikamiUitOpen 0:da34e90f15a3 24 ScfClockTim3(500000); // cutoff frequency: 5 kHz
MikamiUitOpen 0:da34e90f15a3 25
MikamiUitOpen 0:da34e90f15a3 26 int16_t xn[ORDER_+1];
MikamiUitOpen 0:da34e90f15a3 27 for (int n=0; n<=ORDER_; n++)
MikamiUitOpen 0:da34e90f15a3 28 xn[n] = 0;
MikamiUitOpen 0:da34e90f15a3 29
MikamiUitOpen 0:da34e90f15a3 30 while (true)
MikamiUitOpen 0:da34e90f15a3 31 {
MikamiUitOpen 4:a4b03c9a371c 32 xn[0] = adc_.Read_u16() - OFFSET; // Read from A0
MikamiUitOpen 0:da34e90f15a3 33 //-----------------------------------------------
MikamiUitOpen 0:da34e90f15a3 34
MikamiUitOpen 0:da34e90f15a3 35 int32_t yn = 0;
MikamiUitOpen 0:da34e90f15a3 36 for (int k=0; k<=ORDER_; k++)
MikamiUitOpen 0:da34e90f15a3 37 yn = yn + hm_[k]*xn[k];
MikamiUitOpen 0:da34e90f15a3 38
MikamiUitOpen 0:da34e90f15a3 39 for (int k=ORDER_; k>0; k--)
MikamiUitOpen 0:da34e90f15a3 40 xn[k] = xn[k-1]; // move input signals
MikamiUitOpen 0:da34e90f15a3 41
MikamiUitOpen 4:a4b03c9a371c 42 // rounding and devide by 32768 + DC offset
MikamiUitOpen 4:a4b03c9a371c 43 uint16_t yOut = ((yn + 0x8000) >> 15) + OFFSET;
MikamiUitOpen 0:da34e90f15a3 44 //-----------------------------------------------
MikamiUitOpen 4:a4b03c9a371c 45 myDac_.Write(yOut); // Write to DAC
MikamiUitOpen 0:da34e90f15a3 46 }
MikamiUitOpen 0:da34e90f15a3 47 }