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//
// Transistor Gijutu - LPC11U35 ARM Writer
// LCR meter
//
#include "mbed.h"
#include "parts.h"

#include "lcd_P4bit.h"

#define IPC 25 // interrupt per cycle
#define PI 3.14159265358979

int ps1k = 0;   // pre-scaler for measure freq.
int sintable[] = { 8, 9, 11, 12, 13, 14, 14, 14, 14, 13, 12, 10, 8, 7, 5, 3, 2, 1, 1, 1, 1, 2, 3, 4, 6 };
double Vraw[IPC], Iraw[IPC];    // AD convert data
int VorI;
double vcalc[IPC], icalc[IPC];  // waveform buffer for calc.

Ticker f25k;    // interval timer - make sine wave and measure current and voltage

DigitalOut sine0(P0_14);    // R2R DAC bit 0
DigitalOut sine1(P0_2);     // R2R DAC bit 1
DigitalOut sine2(P0_23);    // R2R DAC bit 2
DigitalOut sine3(P0_17);    // R2R DAC bit 3
DigitalOut ISRflag(P0_20);  // interrupt service routine flag

AnalogIn Voltage(p20);  // Voltage ADC
AnalogIn Current(p19);  // Current ADC

// 50KHz interval interrupt
void interval_25k() {   
  ISRflag = 1;
  ++ ps1k;
  if( IPC <= ps1k ) {
    ps1k = 0;
    VorI = !VorI;
  }
  sine0 = sintable[ps1k] & 0x01;    // DAC output - each bit
  sine1 = sintable[ps1k] & 0x02;
  sine2 = sintable[ps1k] & 0x04;
  sine3 = sintable[ps1k] & 0x08;
//
  if( VorI ) Vraw[ps1k] = Voltage.read();    // measure Voltage or Current
  else       Iraw[ps1k] = Current.read();
  ISRflag = 0;
}

int main() {
  int i;
  char s[10];
  double vi, vq, ii, iq;    // voltage/current, in-phase,quad-phase -> vi + jvq, ii + jiq
  double r, x;      // register, reactance -> r + jx
  double a;     // amplitude
  
  // work area initialize
  VorI = 0;
  for( i = 0; IPC > i; i ++ ) Vraw[i] = Iraw[i] = 0.0; 
  // LCD module initialize
  LCD_iniz();
  // start interval interrupt
  f25k.attach_us( &interval_25k, FREQ / IPC );
  // LCD test
  LCD_cmd( 0x80 );
  LCD_puts( "LCR Mete" );
  LCD_cmd( 0xC0 );
  LCD_puts( "r V0.0" );
  // Main routine
  for( ; ; ) {
    // copy raw data to calc. buffer
    for( i = 0; IPC > i; i ++ ) vcalc[i] = Vraw[i], icalc[i] = Iraw[i];
    // calc. in-phase and quad-phase
    vi = vq = ii = iq = 0.0;
    for( i = 0; IPC > i; i ++ ) {
      a = 2 * PI * (double)i / (double)IPC;
      vi = vi + vcalc[i] * sin( a );
      vq = vq + vcalc[i] * cos( a );
      ii = ii - icalc[i] * sin( a );
      iq = iq - icalc[i] * cos( a );
    }
    // gain calc.
    a = ( R3 * ( R4 + R5 ) ) / ( R4 * ( R2 + R3 ) );
    vi /= a;    // voltage real
    vq /= a;    // voltage imaginary
    ii /= R1;   // current real
    iq /= R1;   // current immaginary
    // divide : Z = v / i
    if( 0.0 != ii || 0.0 != iq ) {
      a = ii * ii + iq * iq;
      r = ( ( vi * ii ) + ( vq * iq ) ) / a;
      x = ( ( vq * ii ) - ( vi * iq ) ) / a;
    }
    else {
      r = 999999.9, x = 999999.9;   // hi-Z
    }
    //  display R
    if( 1000.0 > r )        sprintf( s, "R%4.1f  ", r );
    else if( 10000.0 > r )  sprintf( s, "R%2.3fK ", r / 1000.0 );
    else if( 100000.0 > r ) sprintf( s, "R%3.2fK ", r / 1000.0 );
    else sprintf( s, "R ----- " );
    LCD_cmd( 0x80 );
    LCD_puts( s );
    // display X
    if( 0 < x ) {
      // inductance
      x = x / ( 2.0 * PI * FREQ );  // H
      if( 1.0 > x )        sprintf( s, "L%4.1fm ", x * 1000.0 );
      else if( 10.0 > x )  sprintf( s, "L%2.3f  ", x );
      else if( 100.0 > x ) sprintf( s, "L%3.2f  ", x );
      else sprintf( s, "L ----- " );
    }
    else {
      // capacitance
      x = -1000000.0 / ( x * 2.0 * PI * FREQ );    // uF
      if( 1.0 > x )        sprintf( s, "C%4.1fn ", x * 1000.0 );
      else if( 10.0 > x )  sprintf( s, "C%2.3fu ", x );
      else if( 100.0 > x ) sprintf( s, "C%3.2fu ", x );
      else sprintf( s, "C ----- " );
    }
    LCD_cmd( 0xC0 );
    LCD_puts( s );
  }
}