Transistor Gijutsu, October 2014, Special Features Chapter 7,Software of the LCRmeter トランジスタ技術2014年10月号 特集第7章のソフトウェア,サバイバルLCRメータ
Dependencies: mbed
Diff: main.cpp
- Revision:
- 0:b3e41ec91adf
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/main.cpp Thu Aug 28 07:09:42 2014 +0000 @@ -0,0 +1,123 @@ +// +// 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 ); + } +} +