208 lines
8.7 KiB
C++
208 lines
8.7 KiB
C++
/*
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* This program source code file is part of KICAD, a free EDA CAD application.
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*
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* Copyright (C) 2011 jean-pierre.charras
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* Copyright (C) 1992-2011 Kicad Developers, see change_log.txt for contributors.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you may find one here:
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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* or you may search the http://www.gnu.org website for the version 2 license,
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* or you may write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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/* see
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* http://www.desmith.net/NMdS/Electronics/TraceWidth.html
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* http://www.ultracad.com/articles/pcbtemp.pdf
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* for more info
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*/
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#include <cmath>
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#include <wx/wx.h>
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#include <wx/config.h>
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#include <pcb_calculator_frame_base.h>
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#include <pcb_calculator.h>
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#include <UnitSelector.h>
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#include <units_scales.h>
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extern double ReturnDoubleFromString( const wxString& TextValue );
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// Key words to read/write some parameters in config:
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#define KEYWORD_TW_CURRENT wxT( "TW_Track_Current" )
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#define KEYWORD_TW_DELTA_TC wxT( "TW_Delta_TC" )
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#define KEYWORD_TW_TRACK_COPPER_THICKNESS wxT( "TW_Track_CopperThickness" )
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#define KEYWORD_TW_TRACK_LEN wxT( "TW_Track_Len" )
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#define KEYWORD_TW_TRACK_COPPER_THICKNESS_UNIT wxT( "TW_Track_CopperThickness_Unit" )
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#define KEYWORD_TW_TRACK_LEN_UNIT wxT( "TW_Track_Len_Unit" )
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#define KEYWORD_TW_EXTTRACK_WIDTH_UNIT wxT( "TW_ExtTrack_Width_Unit" )
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#define KEYWORD_TW_INTTRACK_WIDTH_UNIT wxT( "TW_IntTrack_Width_Unit" )
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void PCB_CALCULATOR_FRAME::TW_WriteConfig()
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{
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// Save current parameters values in config:
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m_Config->Write( KEYWORD_TW_EXTTRACK_WIDTH_UNIT, m_TW_ExtTrackWidth_choiceUnit->GetSelection() );
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m_Config->Write( KEYWORD_TW_INTTRACK_WIDTH_UNIT, m_TW_IntTrackWidth_choiceUnit->GetSelection() );
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m_Config->Write( KEYWORD_TW_TRACK_COPPER_THICKNESS_UNIT,
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m_TW_CuThickness_choiceUnit->GetSelection() );
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m_Config->Write( KEYWORD_TW_TRACK_LEN_UNIT, m_TW_CuLength_choiceUnit->GetSelection() );
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m_Config->Write( KEYWORD_TW_CURRENT, m_TrackCurrentValue->GetValue() );
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m_Config->Write( KEYWORD_TW_DELTA_TC, m_TrackDeltaTValue->GetValue() );
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m_Config->Write( KEYWORD_TW_TRACK_COPPER_THICKNESS, m_TrackThicknessValue->GetValue() );
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m_Config->Write( KEYWORD_TW_TRACK_LEN, m_TrackLengthValue->GetValue() );
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}
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void PCB_CALCULATOR_FRAME::OnTWCalculateButt( wxCommandEvent& event )
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{
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// Prepare parameters:
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double current = std::abs( ReturnDoubleFromString( m_TrackCurrentValue->GetValue() ) );
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double thickness = std::abs( ReturnDoubleFromString( m_TrackThicknessValue->GetValue() ) );
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double deltaT_C = std::abs( ReturnDoubleFromString( m_TrackDeltaTValue->GetValue() ) );
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double track_len = std::abs( ReturnDoubleFromString( m_TrackLengthValue->GetValue() ) );
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double extTrackWidth;
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double intTrackWidth;
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// Normalize units:
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thickness *= m_TW_CuThickness_choiceUnit->GetUnitScale();
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track_len *= m_TW_CuLength_choiceUnit->GetUnitScale();
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extTrackWidth = TWCalculate( current, thickness, deltaT_C, false );
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intTrackWidth = TWCalculate( current, thickness, deltaT_C, true );
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// Display values:
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wxString msg;
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msg.Printf( wxT( "%g" ), extTrackWidth / m_TW_ExtTrackWidth_choiceUnit->GetUnitScale() );
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m_ExtTrackWidthValue->SetValue( msg );
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msg.Printf( wxT( "%g" ), intTrackWidth / m_TW_IntTrackWidth_choiceUnit->GetUnitScale() );
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m_IntTrackWidthValue->SetValue( msg );
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// Display areas:
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double scale = m_TW_ExtTrackWidth_choiceUnit->GetUnitScale();
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double ext_area = thickness * extTrackWidth;
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msg.Printf( wxT( "%g" ), ext_area / (scale * scale) );
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m_ExtTrackAreaValue->SetValue( msg );
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wxString strunit = m_TW_ExtTrackWidth_choiceUnit->GetUnitName();
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msg = strunit + wxT( " x " ) + strunit;
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m_ExtTrackAreaUnitLabel->SetLabel( msg );
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scale = m_TW_IntTrackWidth_choiceUnit->GetUnitScale();
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double int_area = thickness * intTrackWidth;
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msg.Printf( wxT( "%g" ), int_area / (scale * scale) );
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m_IntTrackAreaValue->SetValue( msg );
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strunit = m_TW_IntTrackWidth_choiceUnit->GetUnitName();
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msg = strunit + wxT( " x " ) + strunit;
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m_IntTrackAreaUnitLabel->SetLabel( msg );
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// Display resistance (assuming using copper ):
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double rho = 1.72e-008; // In Ohms*meter
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double ext_res = rho / ext_area * track_len;
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msg.Printf( wxT( "%g" ), ext_res );
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m_ExtTrackResistValue->SetValue( msg );
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double int_res = rho / int_area * track_len;
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msg.Printf( wxT( "%g" ), int_res );
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m_IntTrackResistValue->SetValue( msg );
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// Display drop voltage
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double ext_drop_volt = ext_res * current;
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msg.Printf( wxT( "%g" ), ext_drop_volt );
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m_ExtTrackVDropValue->SetValue( msg );
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double int_drop_volt = int_res * current;
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msg.Printf( wxT( "%g" ), int_drop_volt );
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m_IntTrackVDropValue->SetValue( msg );
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// Display power loss
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double loss = ext_drop_volt * current;
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msg.Printf( wxT( "%g" ), loss );
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m_ExtTrackLossValue->SetValue( msg );
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loss = int_drop_volt * current;
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msg.Printf( wxT( "%g" ), loss );
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m_IntTrackLossValue->SetValue( msg );
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}
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/* calculate track width for external or internal layers
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*
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* Imax = 0.048 * dT^0.44 * A^0.725 for external layer
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* Imax = 0.024 * dT^0.44 * A^0.725 for internal layer
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* with A = area = aThickness * trackWidth ( in mils )
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* and dT = temperature rise in degree C
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* Of course we want to know trackWidth
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*/
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double PCB_CALCULATOR_FRAME::TWCalculate( double aCurrent, double aThickness, double aDeltaT_C,
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bool aUseInternalLayer )
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{
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double scale = 0.048; // We are using normalize units (sizes in meters)
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if( aUseInternalLayer )
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scale *= 0.024 / 0.048;
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// aThickness is given in normalize units (in meters) and we need mil
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aThickness /= UNIT_MIL;
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/* formula is Imax = scale * dT^0.44 * A^0.725
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* or
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* log(Imax) = log(scale) + 0.44*log(dT)
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* +(0.725*(log(aThickness) + log(trackWidth))
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* log(trackWidth) * 0.725 = ln(Imax) - ln(scale) - 0.44*log(dT) - 0.725*log(aThickness)
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*/
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double dtmp = log( aCurrent ) - log( scale ) - 0.44 * log( aDeltaT_C ) - 0.725 * log( aThickness );
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dtmp /= 0.725;
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double trackWidth = exp( dtmp );
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trackWidth *= UNIT_MIL; // We are using normalize units (sizes in meters) and we have mil
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return trackWidth; // in meters
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}
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void PCB_CALCULATOR_FRAME::TW_Init()
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{
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int tmp;
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wxString msg;
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// Read parameters values:
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m_Config->Read( KEYWORD_TW_EXTTRACK_WIDTH_UNIT, &tmp, 0 );
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m_TW_ExtTrackWidth_choiceUnit->SetSelection( tmp );
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m_Config->Read( KEYWORD_TW_INTTRACK_WIDTH_UNIT, &tmp, 0 );
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m_TW_IntTrackWidth_choiceUnit->SetSelection( tmp );
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m_Config->Read( KEYWORD_TW_TRACK_COPPER_THICKNESS_UNIT, &tmp, 0 );
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m_TW_CuThickness_choiceUnit->SetSelection( tmp );
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m_Config->Read( KEYWORD_TW_TRACK_LEN_UNIT, &tmp, 0 );
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m_TW_CuLength_choiceUnit->SetSelection( tmp );
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m_Config->Read( KEYWORD_TW_CURRENT, &msg, wxT( "1.0" ) );
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m_TrackCurrentValue->SetValue( msg );
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m_Config->Read( KEYWORD_TW_DELTA_TC, &msg, wxT( "10.0" ) );
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m_TrackDeltaTValue->SetValue( msg );
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m_Config->Read( KEYWORD_TW_TRACK_COPPER_THICKNESS, &msg, wxT( "0.035" ) );
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m_TrackThicknessValue->SetValue( msg );
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m_Config->Read( KEYWORD_TW_TRACK_LEN, &msg, wxT( "20" ) );
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m_TrackLengthValue->SetValue( msg );
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// Init formulas text
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m_htmlWinFormulas->AppendToPage( _( "<br><em>The formula (from IPC 2221) is:</em></br>" ) );
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m_htmlWinFormulas->AppendToPage( _( "<br><b>I = K * dT<sup>0.44</sup> * (W*H)<sup>0.725</sup></b></br>" ) );
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m_htmlWinFormulas->AppendToPage( _( "<br>Internal traces : <b>K = 0.024</b></br>" ) );
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m_htmlWinFormulas->AppendToPage( _( "<br>External traces: <b>K = 0.048</b></br>" ) );
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m_htmlWinFormulas->AppendToPage( _( "<br>where:</br>" ) );
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m_htmlWinFormulas->AppendToPage( _( "<br><b>I</b> = maximum current in Amps</br>" ) );
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m_htmlWinFormulas->AppendToPage( _( "<br><b>dT</b> = temperature rise above ambient in deg C</br>" ) );
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m_htmlWinFormulas->AppendToPage( _( "<br><b>W,H</b> = Width and Thickness in mils</br>" ) );
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}
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