不韋 呂 / Mbed 2 deprecated UIT2_FIR_LPF_Direct_FixedFast

FIR filter using DSP instructions for ST Nucleo F401RE.

Dependencies:   UITDSP_ADDA mbed

main.cpp@4:0b3b70b0af0b, 2014-10-30 (annotated)

Committer:
MikamiUitOpen
Date:
Thu Oct 30 02:56:50 2014 +0000
Revision:
4:0b3b70b0af0b
Parent:
3:bfb6d1e6deee
Child:
6:f005cc78b9aa
5

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:797a9c10261e 1 //--------------------------------------------------------------
MikamiUitOpen 0:797a9c10261e 2 // FIR フィルタ，基本的な構造, 固定小数点演算用 DSP 命令を使う
MikamiUitOpen 0:797a9c10261e 3 // Analog Input : A0
MikamiUitOpen 0:797a9c10261e 4 // Analog Output: MCP4922 using SPI
MikamiUitOpen 4:0b3b70b0af0b 5 // 2014/10/29, Copyright (c) 2014 MIKAMI, Naoki
MikamiUitOpen 0:797a9c10261e 6 //--------------------------------------------------------------
MikamiUitOpen 0:797a9c10261e 7
MikamiUitOpen 0:797a9c10261e 8 #include "mbed.h"
MikamiUitOpen 0:797a9c10261e 9
MikamiUitOpen 0:797a9c10261e 10 #include "ADC_Base.hpp" // for ADC not using interrupt
MikamiUitOpen 0:797a9c10261e 11 #include "DAC_MCP4922.hpp" // for DAC MCP4922
MikamiUitOpen 0:797a9c10261e 12 #include "ScfClockTim3.hpp" // for clock supplied to SCF
MikamiUitOpen 0:797a9c10261e 13 #include "Coefficients_200_LPF_Fixed.hpp"
MikamiUitOpen 0:797a9c10261e 14
MikamiUitOpen 0:797a9c10261e 15 using namespace Mikami;
MikamiUitOpen 0:797a9c10261e 16
MikamiUitOpen 3:bfb6d1e6deee 17 const int FS_ = 12000; // Sampling frequency: 12 kHz
MikamiUitOpen 4:0b3b70b0af0b 18 const uint16_t OFFSET = 2047; // Correspond to "0"
MikamiUitOpen 3:bfb6d1e6deee 19 ADC_Base adc_(A0, FS_); // for AD
MikamiUitOpen 3:bfb6d1e6deee 20 DAC_MCP4922 myDac_; // for DA
MikamiUitOpen 0:797a9c10261e 21
MikamiUitOpen 0:797a9c10261e 22 int main()
MikamiUitOpen 0:797a9c10261e 23 {
MikamiUitOpen 0:797a9c10261e 24 ScfClockTim3(500000); // cutoff frequency: 5 kHz
MikamiUitOpen 0:797a9c10261e 25
MikamiUitOpen 0:797a9c10261e 26 int16_t xn[ORDER_+1];
MikamiUitOpen 0:797a9c10261e 27 for (int n=0; n<=ORDER_; n++)
MikamiUitOpen 0:797a9c10261e 28 xn[n] = 0;
MikamiUitOpen 0:797a9c10261e 29
MikamiUitOpen 0:797a9c10261e 30 while (true)
MikamiUitOpen 0:797a9c10261e 31 {
MikamiUitOpen 4:0b3b70b0af0b 32 xn[0] = adc_.Read_u16() - OFFSET; // Read from A0
MikamiUitOpen 0:797a9c10261e 33 //-----------------------------------------------
MikamiUitOpen 0:797a9c10261e 34
MikamiUitOpen 0:797a9c10261e 35 int32_t yn = hm_[ORDER_]*xn[ORDER_];;
MikamiUitOpen 0:797a9c10261e 36 for (int k=0; k<ORDER_; k+=2)
MikamiUitOpen 0:797a9c10261e 37 {
MikamiUitOpen 0:797a9c10261e 38 uint32_t x = __PKHBT(xn[k], xn[k+1], 16);
MikamiUitOpen 0:797a9c10261e 39 uint32_t h = __PKHBT(hm_[k], hm_[k+1], 16);
MikamiUitOpen 0:797a9c10261e 40 yn = __SMLAD(x, h, yn); // Dual multiply and accumulate
MikamiUitOpen 0:797a9c10261e 41 }
MikamiUitOpen 0:797a9c10261e 42 for (int k=ORDER_; k>0; k--)
MikamiUitOpen 0:797a9c10261e 43 xn[k] = xn[k-1]; // move input signals
MikamiUitOpen 0:797a9c10261e 44
MikamiUitOpen 4:0b3b70b0af0b 45 // rounding and devide by 32768 + DC offset
MikamiUitOpen 4:0b3b70b0af0b 46 uint16_t yOut = ((yn + 0x8000) >> 15) + OFFSET;
MikamiUitOpen 0:797a9c10261e 47 //-----------------------------------------------
MikamiUitOpen 4:0b3b70b0af0b 48 myDac_.Write(yOut); // Write to DAC
MikamiUitOpen 0:797a9c10261e 49 }
MikamiUitOpen 0:797a9c10261e 50 }