MPL115.cpp

00001 //**********************
00002 // MPL115.cpp for mbed
00003 //
00004 // MPL115A2 mpl115a2(P0_5,P0_4);
00005 // or
00006 // I2C i2c(P0_5,P0_4);
00007 // MPL115A2 mpl115a2(i2c);
00008 //
00009 // (C)Copyright 2014 All rights reserved by Y.Onodera
00010 // http://einstlab.web.fc2.com
00011 //**********************
00012 
00013 #include "mbed.h"
00014 #include "MPL115.h"
00015 
00016 MPL115A2::MPL115A2 (PinName sda, PinName scl) : _i2c(sda, scl) {
00017     init();
00018 }
00019 MPL115A2::MPL115A2 (I2C& p_i2c) : _i2c(p_i2c) {
00020     init();
00021 }
00022 
00023 
00024 void MPL115A2::start()
00025 {
00026 
00027     // Start Conversion
00028     buf[0] = 0x12;
00029     buf[1] = 0x01;
00030     _i2c.write(MPL115_ADDR, buf, 2);
00031 
00032     wait_ms(5);
00033     
00034     // Read Results
00035     buf[0] = 0x00;
00036     _i2c.write(MPL115_ADDR, buf, 1, false); // no stop, repeated
00037     _i2c.read( MPL115_ADDR, buf, 4);
00038 
00039     Padc.byte.HB=buf[0];
00040     Padc.byte.LB=buf[1];
00041     Tadc.byte.HB=buf[2];
00042     Tadc.byte.LB=buf[3];
00043 
00044 }
00045 
00046 
00047 short MPL115A2::temperature()
00048 {
00049     start();
00050     
00051     Tadc.Val >>= 6;     // to adjust 10 bit
00052     return Tadc.S;
00053 }
00054 
00055 
00056 short MPL115A2::pressure()
00057 {
00058 
00059     // Pcomp = a0 + (b1 + c12 * Tadc) * Padc + b2 * Tadc
00060     int c12x2, a1, a1x1, y1, a2x2, Pcomp;
00061 
00062     start();
00063 
00064     Padc.Val >>= 6;   // to adjust 10 bit
00065     Tadc.Val >>= 6;   // to adjust 10 bit
00066     c12x2 = (((int)c12.S) * (int)Tadc.S) >> 11; // c12x2 = c12 * Tadc
00067     a1 = (int)b1.S + c12x2;                     // a1 = b1 + c12x2
00068     a1x1 = a1 * (int)Padc.S;                    // a1x1 = a1 * Padc
00069     y1 = (((int)a0.S) << 10) + a1x1;            // y1 = a0 + a1x1
00070     a2x2 = (((int)b2.S) * (int)Tadc.S) >> 1;    // a2x2 = b2 * Tadc
00071     Pcomp = (y1 + a2x2) >> 9;                   // Pcomp = y1 + a2x2
00072 
00073     return (short)Pcomp;
00074 
00075     // hPa = (Pcomp/16) * (115.0-50.0)/1023.0 +  50.0
00076 }
00077 
00078 void MPL115A2::init()
00079 {
00080 
00081     buf[0] = 0x04;
00082     _i2c.write(MPL115_ADDR, buf, 1, false); // no stop, repeated
00083     _i2c.read( MPL115_ADDR, buf, 8);
00084     
00085     a0.byte.HB=buf[0];
00086     a0.byte.LB=buf[1];
00087     b1.byte.HB=buf[2];
00088     b1.byte.LB=buf[3];
00089     b2.byte.HB=buf[4];
00090     b2.byte.LB=buf[5];
00091     c12.byte.HB=buf[6];
00092     c12.byte.LB=buf[7];
00093     
00094 }
00095 
00096