File content as of revision 6:bb0e5ef9befe:

//--------------------------------------------------------------
// FIR フィルタ，基本的な構造, 固定小数点演算を使う
//      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 = 0;
        for (int k=0; k<=ORDER_; k++)
            yn = yn + hm_[k]*xn[k];

        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
    }
}