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@8:d226de4c3951, 2015-11-16 (annotated)

Committer:
MikamiUitOpen
Date:
Mon Nov 16 02:24:22 2015 +0000
Revision:
8:d226de4c3951
Parent:
6:f005cc78b9aa 
9

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 8:d226de4c3951 5 // 2015/11/16, Copyright (c) 2015 MIKAMI, Naoki
MikamiUitOpen 0:797a9c10261e 6 //--------------------------------------------------------------
MikamiUitOpen 0:797a9c10261e 7
MikamiUitOpen 8:d226de4c3951 8 #include "ADC_BuiltIn.hpp" // for ADC not using interrupt
MikamiUitOpen 8:d226de4c3951 9 #include "DAC_MCP4921.hpp" // for DAC MCP4921, MCP4922
MikamiUitOpen 0:797a9c10261e 10 #include "Coefficients_200_LPF_Fixed.hpp"
MikamiUitOpen 0:797a9c10261e 11
MikamiUitOpen 0:797a9c10261e 12 using namespace Mikami;
MikamiUitOpen 0:797a9c10261e 13
MikamiUitOpen 8:d226de4c3951 14 const int FS_ = 12000; // Sampling frequency: 12 kHz
MikamiUitOpen 4:0b3b70b0af0b 15 const uint16_t OFFSET = 2047; // Correspond to "0"
MikamiUitOpen 8:d226de4c3951 16 ADC_BuiltIn adc_(A0, FS_); // for AD
MikamiUitOpen 8:d226de4c3951 17 DAC_MCP4921 myDac_; // for DA
MikamiUitOpen 0:797a9c10261e 18
MikamiUitOpen 0:797a9c10261e 19 int main()
MikamiUitOpen 0:797a9c10261e 20 {
MikamiUitOpen 6:f005cc78b9aa 21 myDac_.ScfClockTim3(500000); // cutoff frequency: 5 kHz
MikamiUitOpen 0:797a9c10261e 22
MikamiUitOpen 0:797a9c10261e 23 int16_t xn[ORDER_+1];
MikamiUitOpen 0:797a9c10261e 24 for (int n=0; n<=ORDER_; n++)
MikamiUitOpen 0:797a9c10261e 25 xn[n] = 0;
MikamiUitOpen 0:797a9c10261e 26
MikamiUitOpen 0:797a9c10261e 27 while (true)
MikamiUitOpen 0:797a9c10261e 28 {
MikamiUitOpen 4:0b3b70b0af0b 29 xn[0] = adc_.Read_u16() - OFFSET; // Read from A0
MikamiUitOpen 0:797a9c10261e 30 //-----------------------------------------------
MikamiUitOpen 0:797a9c10261e 31
MikamiUitOpen 0:797a9c10261e 32 int32_t yn = hm_[ORDER_]*xn[ORDER_];;
MikamiUitOpen 0:797a9c10261e 33 for (int k=0; k<ORDER_; k+=2)
MikamiUitOpen 0:797a9c10261e 34 {
MikamiUitOpen 0:797a9c10261e 35 uint32_t x = __PKHBT(xn[k], xn[k+1], 16);
MikamiUitOpen 0:797a9c10261e 36 uint32_t h = __PKHBT(hm_[k], hm_[k+1], 16);
MikamiUitOpen 0:797a9c10261e 37 yn = __SMLAD(x, h, yn); // Dual multiply and accumulate
MikamiUitOpen 0:797a9c10261e 38 }
MikamiUitOpen 0:797a9c10261e 39 for (int k=ORDER_; k>0; k--)
MikamiUitOpen 0:797a9c10261e 40 xn[k] = xn[k-1]; // move input signals
MikamiUitOpen 0:797a9c10261e 41
MikamiUitOpen 4:0b3b70b0af0b 42 // rounding and devide by 32768 + DC offset
MikamiUitOpen 8:d226de4c3951 43 uint16_t yOut = ((yn + 0x4000) >> 15) + OFFSET;
MikamiUitOpen 0:797a9c10261e 44 //-----------------------------------------------
MikamiUitOpen 4:0b3b70b0af0b 45 myDac_.Write(yOut); // Write to DAC
MikamiUitOpen 0:797a9c10261e 46 }
MikamiUitOpen 0:797a9c10261e 47 }