FIR filter using DSP instructions for ST Nucleo F401RE.
Dependencies: UITDSP_ADDA mbed
main.cpp
- Committer:
- MikamiUitOpen
- Date:
- 2014-11-12
- Revision:
- 6:f005cc78b9aa
- Parent:
- 4:0b3b70b0af0b
- Child:
- 8:d226de4c3951
File content as of revision 6:f005cc78b9aa:
//-------------------------------------------------------------- // 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 // Analog Input : A0 // Analog Output: MCP4922 using SPI // 2014/11/12, Copyright (c) 2014 MIKAMI, Naoki //-------------------------------------------------------------- #include "mbed.h" #include "ADC_Base.hpp" // for ADC not using interrupt #include "DAC_MCP4922.hpp" // for DAC MCP4922 #include "Coefficients_200_LPF_Fixed.hpp" using namespace Mikami; const int FS_ = 12000; // Sampling frequency: 12 kHz const uint16_t OFFSET = 2047; // Correspond to "0" ADC_Base adc_(A0, FS_); // for AD DAC_MCP4922 myDac_; // for DA int main() { myDac_.ScfClockTim3(500000); // cutoff frequency: 5 kHz int16_t xn[ORDER_+1]; for (int n=0; n<=ORDER_; n++) xn[n] = 0; while (true) { xn[0] = adc_.Read_u16() - OFFSET; // Read from A0 //----------------------------------------------- int32_t yn = hm_[ORDER_]*xn[ORDER_];; for (int k=0; k<ORDER_; k+=2) { uint32_t x = __PKHBT(xn[k], xn[k+1], 16); uint32_t h = __PKHBT(hm_[k], hm_[k+1], 16); yn = __SMLAD(x, h, yn); // Dual multiply and accumulate } for (int k=ORDER_; k>0; k--) xn[k] = xn[k-1]; // move input signals // rounding and devide by 32768 + DC offset uint16_t yOut = ((yn + 0x8000) >> 15) + OFFSET; //----------------------------------------------- myDac_.Write(yOut); // Write to DAC } }