baro.cpp

00001 #ifdef  INC_BARO
00002 
00003 #include "mbed.h"
00004 #include "baro.h"
00005 #include "BufferedSerial.h"
00006 
00007 //BufferedSerial  pc          (PA_2, PA_3, 512, 4, NULL);    //  Pins 16, 17    tx, rx to pc via usb lead
00008 //I2C i2c                     (PB_7, PB_6);   //  Pins 58, 59 For 24LC64 eeprom
00009 extern  BufferedSerial  pc;
00010 extern  I2C i2c;
00011 const int ACK     = 1;
00012 const int NAK     = 0;
00013 const int NOM_PASCALS   = 100000;
00014 const int HYSTERESIS_PASCALS = 50;
00015 
00016 MPL3115A2::MPL3115A2    ()  {   //  Constructor
00017         good = true;
00018 //        mode = 0x39;  //  continuous convert
00019         mode = 0x38;    //  one shot
00020         Temp = Pres = Alti = Adju = 0.0;
00021         if  (!RegRd (0x0c, 1, dest))
00022             good = false;
00023         else if (dest[0] != 196)
00024             good = false;
00025 }
00026 
00027 bool    MPL3115A2::busy_check  ()  {
00028     char    c;
00029     RegRd   (0x26, 1, &c);
00030     c &= 2;
00031     if  (c == 0)
00032         return  false;  //  free, i.e. not busy
00033     return  true;       //  busy, conversion in progress
00034 }
00035 
00036 void    MPL3115A2::reset_zero_inHg  ()  {
00037     double tmp;
00038     Adju = 0.0;
00039     tmp = inHg_vacuum (); //  sets Adju
00040     Adju = tmp;
00041 }
00042 double  MPL3115A2::Temperature ()  {    return  Temp;   }
00043 double  MPL3115A2::Pressure    ()  {    return  Pres;   }
00044 double  MPL3115A2::Altitude    ()  {    return  Alti;   }
00045 double  MPL3115A2::inHg_vacuum ()  {
00046     double  inHg = 0.0 - Pres;   //  one atmospheres worth of Pascals. Note 1 bar is not the same, 1 bar = 100000 Pa
00047     inHg *= 0.000295299833;
00048     return  inHg - Adju;
00049 }
00050 void    MPL3115A2::mode_alti   ()  {
00051 //    mode = 0xb9;
00052     mode = 0xb8;
00053 }
00054 void    MPL3115A2::mode_pres   ()  {
00055 //    mode = 0x39;
00056     mode = 0x38;
00057 }
00058 /*********************************************************\
00059 * IIC Write Register
00060 \*********************************************************/
00061 bool MPL3115A2::RegWr  (int reg, char val)
00062 {
00063     bool    rv = true;
00064     i2c.start   ();
00065     if  (i2c.write   (0xc0)     != ACK) rv = false;  //  Returns '0' - NAK was received '1' - ACK was received, '2' - timeout
00066     if  (i2c.write   (reg)      != ACK) rv = false;
00067     if  (i2c.write   (val)      != ACK) rv = false;
00068     i2c.stop    ();
00069     return  rv;
00070 }
00071 
00072 /*********************************************************\
00073 * IIC Read One Or More Registers into array
00074 \*********************************************************/
00075 bool MPL3115A2::RegRd  (int reg1, int len, char *array)
00076 {
00077     int acknak;
00078     bool    rv = true;
00079     i2c.start   ();
00080     if  (i2c.write   (0xc0) != ACK)     rv = false;  //  Returns '0' - NAK was received '1' - ACK was received, '2' - timeout
00081     if  (i2c.write   (reg1) != ACK)     rv = false;
00082     i2c.start   ();             // Send Repeat Start
00083     if  (i2c.write   (0xc1) != ACK)     rv = false;
00084     acknak = ACK;
00085     while (len > 0) {                                 // Read Register Values
00086         len--;
00087         if  (len == 0)    acknak = NAK;
00088         *array++ = i2c.read    (acknak);
00089     }
00090     i2c.stop    ();
00091     return  rv;
00092 }
00093 
00094 bool    MPL3115A2::Update    ()   {   //  Returns true on apparent success
00095     bool    rv = true;
00096     int32_t ta;
00097     if  (busy_check())  {   //  "User shall read the value of the OST bit before writing to this bit again." - done here.
00098         pc.printf   ("Call to Barometer Update while busy error\r\n");
00099         return  false;  //  Can not initiate new conversion, will not update Temp, Pres, Alti
00100     }
00101     Pres = Alti = -1.0; //  Gives added clue if call to Update fails
00102     if  (!RegRd (1, 5, dest))       rv = false;    //  Read 3 pressure + 2 temperature registers, then kick-start new conversion
00103     if  (!RegWr (0x26, mode | 2))   rv = false;    //  bit 1 is OST one shot mode, bits 3-5 are 128x oversampling. This starts new conversion
00104     if  (!rv)
00105         return  false;  //  register read or write failed, Pres and Alti = -1.0 also
00106     Temp = ((double) ((dest[3] << 4) | (dest[4] >> 4))) / 16.0; //  Temperature
00107     if  (mode & 0x80)  {    //  Altimeter mode
00108         ta = (dest[0] << 24) | (dest[1] << 16) | ((dest[2] & 0xf0) << 8);   //  preserve sign bit
00109         ta /= (1 << 12);
00110         Alti = ((double) ta) / 16.0;
00111         Pres = 0.0;
00112     }
00113     else    {   //  Pressure mode
00114         Pres = ((double) ((dest[0] << 12) | (dest[1] << 4) | (dest[2] >> 4))) / 4.0;
00115         Alti = 0.0;
00116     }
00117     return  true;
00118 }
00119 
00120 
00121 /*
00122 int main()
00123 {
00124     double  Pres, Alt, inHg, Heat;
00125     i2c.frequency(400000);      //  Speed 400000 max.
00126     class   MPL3115A2   baro    ;
00127     int q;      //  Note address bits 3-1 to match addr pins on 24LC16 memory device
00128     for (int i = 0; i < 255; i += 2)    {   //  Search for devices at all possible i2c addresses
00129         i2c.start();
00130         wait_ms (1);
00131         q = i2c.write(i);   //  may return error code 2 when no start issued
00132         switch  (q) {
00133             case    ACK:
00134                 pc.printf   ("I2C device found at 0x%x\r\n", i);
00135             case    NAK:      //  Device not seen at this address
00136                 break;
00137             case    2:      //  write reports timeout
00138                 pc.printf   ("I2C Timeout at addr %2x\r\n", i);
00139                 break;
00140             default:
00141                 pc.printf   ("Unknown error %d in check_24LC64\r\n", q);
00142                 break;
00143         }
00144     }
00145     i2c.stop();
00146     baro.mode_pres  ();
00147     pc.printf   ("baro good flag %s\r\n", baro.good ? "true":"false");
00148     bool    rv;
00149     q = -3;
00150     while(1) {
00151         q++;
00152         if  (q == 0)    baro.reset_zero_inHg();
00153         myled = 1; // LED is ON
00154         wait(0.3); // 200 ms
00155 //        pc.printf   ("busy_check %s\r\n", baro.busy_check() ? "true":"false");
00156         myled = 0; // LED is OFF
00157         wait(0.8); // 1 sec
00158 //        pc.printf   ("busy_check %s\r\n", baro.busy_check() ? "true":"false");
00159         rv  = baro.Update ();
00160         Pres = baro.Pressure();
00161         Alt = baro.Altitude();
00162         inHg = baro.inHg_vacuum();
00163         Heat = baro.Temperature();
00164 const int NOM_PASCALS   = 100000;
00165 const int HYSTERESIS_PASCALS = 50;
00166         if  (Pres > (NOM_PASCALS + HYSTERESIS_PASCALS))
00167             pump = 1;
00168         if  (Pres < (NOM_PASCALS - HYSTERESIS_PASCALS))
00169             pump = 0;
00170 //        pc.printf   ("Pres\t%.2f Pa\tAlt\t%.1f m\t%+000.1f inHg\tTemp\t%.1f C, %s\r\n", baro.Pressure(), baro.Altitude(), baro.inHg_vacuum (), baro.Temperature(), rv ? "true":"false");
00171         pc.printf   ("Pres\t%.2f Pa\tAlt\t%.1f m\t%+000.1f inHg\tTemp\t%.1f C, %s\r\n", Pres, Alt, inHg, Heat, rv ? "true":"false");
00172 //        rv  = baro.Update ();
00173     }
00174 }
00175 */
00176 #endif