protected override void Dispose(bool disposing)
{
if (disposing)
{
// clean up any managed code objects
_irqPort.Dispose();
_spi.Dispose();
}
// clean up any unmanaged code objects
// dispose of our base object
base.Dispose(disposing);
}
/// <summary>
///
/// SPI interface for the MPL115A barometric sensor.
/// Created by deepnarc, deepnarc at gmail.com
///
/// Netduino platform
///
/// Sensor Breakout---------Netduino
/// ================================
/// SDN---------------------optional
/// CSN---------------------pin 0 (user definable)
/// SDO---------------------pin 12
/// SDI---------------------pin 11
/// SCK---------------------pin 13
/// GND---------------------GND
/// VDO---------------------VCC (3.3V)
///
/// References: (1) Freescale Semiconductor, Application Note, AN3785, Rev 5, 7/2009 by John Young
/// provided the code for the manipulations of the sensor coefficients; the original comments
/// were left in place without modification in that section. (2) Freescale Semiconductor, Document
/// Number: MPL115A1, Rev 6, 10/2011. (3) MPL115A1 SPI Digital Barometer Test Code Created on:
/// September 30, 2010 By: Jeremiah McConnell - miah at miah.com, Portions: Jim Lindblom - jim at
/// sparkfun.com. (4) MPL115A1 SPI Digital Barometer Test Code Created on: April 20, 2010 By: Jim
/// Lindblom - jim at sparkfun.com.
///
/// </summary>
public static double calculatePressure()
{
SPI SPI_Out = new SPI(new SPI.Configuration(
(Cpu.Pin)FEZ_Pin.Digital.Di7, // SS-pin
false, // SS-pin active state
0, // The setup time for the SS port
0, // The hold time for the SS port
false, // The idle state of the clock
true, // The sampling clock edge
1000, // The SPI clock rate in KHz
SPI.SPI_module.SPI1 // The used SPI bus (refers to a MOSI MISO and SCLK pinset)
)
);
string decPcomp_out;
sbyte sia0MSB, sia0LSB;
sbyte sib1MSB, sib1LSB;
sbyte sib2MSB, sib2LSB;
sbyte sic12MSB, sic12LSB;
sbyte sic11MSB, sic11LSB;
sbyte sic22MSB, sic22LSB;
int sia0, sib1, sib2, sic12, sic11, sic22;
uint uiPadc, uiTadc;
byte uiPH, uiPL, uiTH, uiTL;
long lt1, lt2, lt3, si_c11x1, si_a11, si_c12x2;
long si_a1, si_c22x2, si_a2, si_a1x1, si_y1, si_a2x2;
float siPcomp;//, decPcomp;
// start pressure & temp conversions
// command byte + r/w bit
const byte com1_writeData = 0x24 & 0x7F;
const byte com2_writeData = 0x00 & 0x7F;
byte[] WriteBuffer = { com1_writeData, com2_writeData };
SPI_Out.Write(WriteBuffer);
Thread.Sleep(3);
// write(0x24, 0x00); // Start Both Conversions
// write(0x20, 0x00); // Start Pressure Conversion
// write(0x22, 0x00); // Start temperature conversion
// delay_ms(10); // Typical wait time is 3ms
// read pressure
// address byte + r/w bit
// data byte + r/w bit
const byte PRESHw_writeData = 0x00 | 0x80;
const byte PRESHr_writeData = 0x00 | 0x80;
const byte PRESLw_writeData = 0x02 | 0x80;
const byte PRESLr_writeData = 0x00 | 0x80;
const byte TEMPHw_writeData = 0x04 | 0x80;
const byte TEMPHr_writeData = 0x00 | 0x80;
const byte TEMPLw_writeData = 0x06 | 0x80;
const byte TEMPLr_writeData = 0x00 | 0x80;
const byte BLANK1r_writeData = 0x00 | 0x80;
byte[] press_writeData = { PRESHw_writeData, PRESHr_writeData, PRESLw_writeData, PRESLr_writeData,
TEMPHw_writeData, TEMPHr_writeData, TEMPLw_writeData, TEMPLr_writeData, BLANK1r_writeData };
byte[] press_readBuffer = new byte[9];
SPI_Out.WriteRead(press_writeData, press_readBuffer);
uiPH = press_readBuffer[1];
uiPL = press_readBuffer[3];
uiTH = press_readBuffer[5];
uiTL = press_readBuffer[7];
uiPadc = (uint)uiPH << 8;
uiPadc += (uint)uiPL & 0x00FF;
uiTadc = (uint)uiTH << 8;
uiTadc += (uint)uiTL & 0x00FF;
// read coefficients
// address byte + r/w bit
// data byte + r/w bit
const byte A0MSBw_writeData = 0x08 | 0x80;
const byte A0MSBr_writeData = 0x00 | 0x80;
const byte A0LSBw_writeData = 0x0A | 0x80;
const byte A0LSBr_writeData = 0x00 | 0x80;
const byte B1MSBw_writeData = 0x0C | 0x80;
const byte B1MSBr_writeData = 0x00 | 0x80;
const byte B1LSBw_writeData = 0x0E | 0x80;
const byte B1LSBr_writeData = 0x00 | 0x80;
const byte B2MSBw_writeData = 0x10 | 0x80;
const byte B2MSBr_writeData = 0x00 | 0x80;
const byte B2LSBw_writeData = 0x12 | 0x80;
const byte B2LSBr_writeData = 0x00 | 0x80;
const byte C12MSBw_writeData = 0x14 | 0x80;
const byte C12MSBr_writeData = 0x00 | 0x80;
const byte C12LSBw_writeData = 0x16 | 0x80;
const byte C12LSBr_writeData = 0x00 | 0x80;
const byte C11MSBw_writeData = 0x18 | 0x80;
const byte C11MSBr_writeData = 0x00 | 0x80;
const byte C11LSBw_writeData = 0x1A | 0x80;
const byte C11LSBr_writeData = 0x00 | 0x80;
const byte C22MSBw_writeData = 0x1C | 0x80;
const byte C22MSBr_writeData = 0x00 | 0x80;
const byte C22LSBw_writeData = 0x1E | 0x80;
const byte C22LSBr_writeData = 0x00 | 0x80;
const byte BLANK2r_writeData = 0x00 | 0x80;
byte[] coeff_writeData = { A0MSBw_writeData, A0MSBr_writeData, A0LSBw_writeData, A0LSBr_writeData, B1MSBw_writeData,
B1MSBr_writeData, B1LSBw_writeData, B1LSBr_writeData, B2MSBw_writeData, B2MSBr_writeData,
B2LSBw_writeData, B2LSBr_writeData, C12MSBw_writeData, C12MSBr_writeData, C12LSBw_writeData,
C12LSBr_writeData, C11MSBw_writeData, C11MSBr_writeData, C11LSBw_writeData, C11LSBr_writeData,
C22MSBw_writeData, C22MSBr_writeData, C22LSBw_writeData, C22LSBr_writeData, BLANK2r_writeData };
byte[] coeff_readBuffer = new byte[25];
SPI_Out.WriteRead(coeff_writeData, coeff_readBuffer);
//====================================================
// MPL115A Placing Coefficients into 16 bit variables
//====================================================
//coeff a0 16bit
sia0MSB = (sbyte)coeff_readBuffer[1];
sia0LSB = (sbyte)coeff_readBuffer[3];
sia0 = (int)sia0MSB << 8; //s16 type //Shift to MSB
sia0 += (int)sia0LSB & 0x00FF; //Add LSB to 16bit number
//coeff b1 16bit
sib1MSB = (sbyte)coeff_readBuffer[5];
sib1LSB = (sbyte)coeff_readBuffer[7];
sib1 = (int)sib1MSB << 8; //Shift to MSB
sib1 += (int)sib1LSB & 0x00FF; //Add LSB to 16bit number
//coeff b2 16bit
sib2MSB = (sbyte)coeff_readBuffer[9];
sib2LSB = (sbyte)coeff_readBuffer[11];
sib2 = (int)sib2MSB << 8; //Shift to MSB
sib2 += (int)sib2LSB & 0x00FF; //Add LSB to 16bit number
//coeff c12 14bit
sic12MSB = (sbyte)coeff_readBuffer[13];
sic12LSB = (sbyte)coeff_readBuffer[15];
sic12 = (int)sic12MSB << 8; //Shift to MSB only by 8 for MSB
sic12 += (int)sic12LSB & 0x00FF;
//coeff c11 11bit
sic11MSB = (sbyte)coeff_readBuffer[17];
sic11LSB = (sbyte)coeff_readBuffer[19];
sic11 = (int)sic11MSB << 8; //Shift to MSB only by 8 for MSB
sic11 += (int)sic11LSB & 0x00FF;
//coeff c22 11bit
sic22MSB = (sbyte)coeff_readBuffer[21];
sic22LSB = (sbyte)coeff_readBuffer[23];
sic22 = (int)sic22MSB << 8; //Shift to MSB only by 8 for MSB
sic22 += (int)sic22LSB & 0x00FF;
//===================================================
//Coefficient 9 equation compensation
//===================================================
//
//Variable sizes:
//For placing high and low bytes of the Memory addresses for each of the 6 coefficients:
//signed char (S8) sia0MSB, sia0LSB, sib1MSB,sib1LSB, sib2MSB,sib2LSB, sic12MSB,sic12LSB, sic11MSB,sic11LSB, sic22MSB,sic22LSB; //
//Variable for use in the compensation, this is the 6 coefficients in 16bit form, MSB+LSB.
//signed int (S16) sia0, sib1, sib2, sic12, sic11, sic22;
//
//Variable used to do large calculation as 3 temp variables in the process below
//signed long (S32) lt1, lt2, lt3;
//
//Variables used for Pressure and Temperature Raw.
//unsigned int (U16) uiPadc, uiTadc.
//signed (N=number of bits in coefficient, F-fractional bits) //s(N,F)
//The below Pressure and Temp or uiPadc and uiTadc are shifted from the MSB+LSB values to remove the zeros in the LSB since this
// 10bit number is stored in 16 bits. i.e 0123456789XXXXXX becomes 0000000123456789
uiPadc = uiPadc >> 6; //Note that the PressCntdec is the raw value from the MPL115A data address. Its shifted >>6 since its 10 bit.
uiTadc = uiTadc >> 6; //Note that the TempCntdec is the raw value from the MPL115A data address. Its shifted >>6 since its 10 bit.
//******* STEP 1 c11x1= c11 * Padc
lt1 = (long)sic11; // s(16,27) s(N,F+zeropad) goes from s(11,10)+11ZeroPad = s(11,22) => Left Justified = s(16,27)
lt2 = (long)uiPadc; // u(10,0) s(N,F)
lt3 = lt1 * lt2; // s(26,27) /c11*Padc
si_c11x1 = (long)lt3; // s(26,27)- EQ 1 =c11x1 /checked
//divide this hex number by 2^30 to get the correct decimal value.
//b1 =s(14,11) => s(16,13) Left justified
//******* STEP 2 a11= b1 + c11x1
lt1 = ((long)sib1) << 14; // s(30,27) b1=s(16,13) Shift b1 so that the F matches c11x1(shift by 14)
lt2 = (long)si_c11x1; // s(26,27) //ensure fractional bits are compatible
lt3 = lt1 + lt2; // s(30,27) /b1+c11x1
si_a11 = (long)(lt3 >> 14); // s(16,13) - EQ 2 =a11 Convert this block back to s(16,X)
//******* STEP 3 c12x2= c12 * Tadc
// sic12 is s(14,13)+9zero pad = s(16,15)+9 => s(16,24) left justified
lt1 = (long)sic12; // s(16,24)
lt2 = (long)uiTadc; // u(10,0)
lt3 = lt1 * lt2; // s(26,24)
si_c12x2 = (long)lt3; // s(26,24) - EQ 3 =c12x2 /checked
//******* STEP 4 a1= a11 + c12x2
lt1 = ((long)si_a11 << 11); // s(27,24) This is done by s(16,13) <<11 goes to s(27,24) to match c12x2's F part
lt2 = (long)si_c12x2; // s(26,24)
lt3 = lt1 + lt2; // s(27,24) /a11+c12x2
si_a1 = (long)lt3 >> 11; // s(16,13) - EQ 4 =a1 /check
//******* STEP 5 c22x2= c22 * Tadc
// c22 is s(11,10)+9zero pad = s(11,19) => s(16,24) left justified
lt1 = (long)sic22; // s(16,30) This is done by s(11,10) + 15 zero pad goes to s(16,15)+15, to s(16,30)
lt2 = (long)uiTadc; // u(10,0)
lt3 = lt1 * lt2; // s(26,30) /c22*Tadc
si_c22x2 = (long)(lt3); // s(26,30) - EQ 5 /=c22x2
//******* STEP 6 a2= b2 + c22x2
//WORKS and loses the least in data. One extra execution. Note how the 31 is really a 32 due to possible overflow.
// b2 is s(16,14) User shifted left to => s(31,29) to match c22x2 F value
lt1 = ((long)sib2 << 15); //s(31,29)
lt2 = ((long)si_c22x2 >> 1); //s(25,29) s(26,30) goes to >>16 s(10,14) to match F from sib2
lt3 = lt1 + lt2; //s(32,29) but really is a s(31,29) due to overflow the 31 becomes a 32.
si_a2 = ((long)lt3 >> 16); //s(16,13)
//******* STEP 7 a1x1= a1 * Padc
lt1 = (long)si_a1; // s(16,13)
lt2 = (long)uiPadc; // u(10,0)
lt3 = lt1 * lt2; // s(26,13) /a1*Padc
si_a1x1 = (long)(lt3); // s(26,13) - EQ 7 /=a1x1 /check
//******* STEP 8 y1= a0 + a1x1
// a0 = s(16,3)
lt1 = ((long)sia0 << 10); // s(26,13) This is done since has to match a1x1 F value to add. So S(16,3) <<10 = S(26,13)
lt2 = (long)si_a1x1; // s(26,13)
lt3 = lt1 + lt2; // s(26,13) /a0+a1x1
si_y1 = ((long)lt3 >> 10); // s(16,3) - EQ 8 /=y1 /check
//******* STEP 9 a2x2= a2 *Tadc
lt1 = (long)si_a2; // s(16,13)
lt2 = (long)uiTadc; // u(10,0)
lt3 = lt1 * lt2; // s(26,13) /a2*Tadc
si_a2x2 = (long)(lt3); // s(26,13) - EQ 9 /=a2x2
//******* STEP 10 pComp = y1 +a2x2
// y1= s(16,3)
lt1 = ((long)si_y1 << 10); // s(26,13) This is done to match a2x2 F value so addition can match. s(16,3) <<10
lt2 = (long)si_a2x2; // s(26,13)
lt3 = lt1 + lt2; // s(26,13) /y1+a2x2
// FIXED POINT RESULT WITH ROUNDING:
siPcomp = (long)lt3 >> 13; // goes to no fractional parts since this is an ADC count.
//decPcomp is defined as a floating point number.
//Conversion to Decimal value from 1023 ADC count value. ADC counts are 0 to 1023. Pressure is 50 to 115kPa correspondingly.
var decPcomp = (double)((65.0 / 1023.0) * siPcomp) + 50;
var decPcompHg = decPcomp*0.295300586466965;
decPcomp_out = decPcomp.ToString();
Debug.Print("decPcomp: " + decPcomp_out + " millibars: " + decPcompHg);
SPI_Out.Dispose();
return decPcompHg;
}