Diff: baro.cpp

Revision:

3:43cb067ecd00

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/baro.cpp	Mon Jul 27 08:44:59 2020 +0000
@@ -0,0 +1,176 @@
+#ifdef  INC_BARO
+
+#include "mbed.h"
+#include "baro.h"
+#include "BufferedSerial.h"
+
+//BufferedSerial  pc          (PA_2, PA_3, 512, 4, NULL);    //  Pins 16, 17    tx, rx to pc via usb lead
+//I2C i2c                     (PB_7, PB_6);   //  Pins 58, 59 For 24LC64 eeprom
+extern  BufferedSerial  pc;
+extern  I2C i2c;
+const int ACK     = 1;
+const int NAK     = 0;
+const int NOM_PASCALS   = 100000;
+const int HYSTERESIS_PASCALS = 50;
+
+MPL3115A2::MPL3115A2    ()  {   //  Constructor
+        good = true;
+//        mode = 0x39;  //  continuous convert
+        mode = 0x38;    //  one shot
+        Temp = Pres = Alti = Adju = 0.0;
+        if  (!RegRd (0x0c, 1, dest))
+            good = false;
+        else if (dest[0] != 196)
+            good = false;
+}
+
+bool    MPL3115A2::busy_check  ()  {
+    char    c;
+    RegRd   (0x26, 1, &c);
+    c &= 2;
+    if  (c == 0)
+        return  false;  //  free, i.e. not busy
+    return  true;       //  busy, conversion in progress
+}
+
+void    MPL3115A2::reset_zero_inHg  ()  {
+    double tmp;
+    Adju = 0.0;
+    tmp = inHg_vacuum (); //  sets Adju
+    Adju = tmp;
+}
+double  MPL3115A2::Temperature ()  {    return  Temp;   }
+double  MPL3115A2::Pressure    ()  {    return  Pres;   }
+double  MPL3115A2::Altitude    ()  {    return  Alti;   }
+double  MPL3115A2::inHg_vacuum ()  {
+    double  inHg = 0.0 - Pres;   //  one atmospheres worth of Pascals. Note 1 bar is not the same, 1 bar = 100000 Pa
+    inHg *= 0.000295299833;
+    return  inHg - Adju;
+}
+void    MPL3115A2::mode_alti   ()  {
+//    mode = 0xb9;
+    mode = 0xb8;
+}
+void    MPL3115A2::mode_pres   ()  {
+//    mode = 0x39;
+    mode = 0x38;
+}
+/*********************************************************\
+* IIC Write Register
+\*********************************************************/
+bool MPL3115A2::RegWr  (int reg, char val)
+{
+    bool    rv = true;
+    i2c.start   ();
+    if  (i2c.write   (0xc0)     != ACK) rv = false;  //  Returns '0' - NAK was received '1' - ACK was received, '2' - timeout
+    if  (i2c.write   (reg)      != ACK) rv = false;
+    if  (i2c.write   (val)      != ACK) rv = false;
+    i2c.stop    ();
+    return  rv;
+}
+
+/*********************************************************\
+* IIC Read One Or More Registers into array
+\*********************************************************/
+bool MPL3115A2::RegRd  (int reg1, int len, char *array)
+{
+    int acknak;
+    bool    rv = true;
+    i2c.start   ();
+    if  (i2c.write   (0xc0) != ACK)     rv = false;  //  Returns '0' - NAK was received '1' - ACK was received, '2' - timeout
+    if  (i2c.write   (reg1) != ACK)     rv = false;
+    i2c.start   ();             // Send Repeat Start
+    if  (i2c.write   (0xc1) != ACK)     rv = false;
+    acknak = ACK;
+    while (len > 0) {                                 // Read Register Values
+        len--;
+        if  (len == 0)    acknak = NAK;
+        *array++ = i2c.read    (acknak);
+    }
+    i2c.stop    ();
+    return  rv;
+}
+
+bool    MPL3115A2::Update    ()   {   //  Returns true on apparent success
+    bool    rv = true;
+    int32_t ta;
+    if  (busy_check())  {   //  "User shall read the value of the OST bit before writing to this bit again." - done here.
+        pc.printf   ("Call to Barometer Update while busy error\r\n");
+        return  false;  //  Can not initiate new conversion, will not update Temp, Pres, Alti
+    }
+    Pres = Alti = -1.0; //  Gives added clue if call to Update fails
+    if  (!RegRd (1, 5, dest))       rv = false;    //  Read 3 pressure + 2 temperature registers, then kick-start new conversion
+    if  (!RegWr (0x26, mode | 2))   rv = false;    //  bit 1 is OST one shot mode, bits 3-5 are 128x oversampling. This starts new conversion
+    if  (!rv)
+        return  false;  //  register read or write failed, Pres and Alti = -1.0 also
+    Temp = ((double) ((dest[3] << 4) | (dest[4] >> 4))) / 16.0; //  Temperature
+    if  (mode & 0x80)  {    //  Altimeter mode
+        ta = (dest[0] << 24) | (dest[1] << 16) | ((dest[2] & 0xf0) << 8);   //  preserve sign bit
+        ta /= (1 << 12);
+        Alti = ((double) ta) / 16.0;
+        Pres = 0.0;
+    }
+    else    {   //  Pressure mode
+        Pres = ((double) ((dest[0] << 12) | (dest[1] << 4) | (dest[2] >> 4))) / 4.0;
+        Alti = 0.0;
+    }
+    return  true;
+}
+
+
+/*
+int main()
+{
+    double  Pres, Alt, inHg, Heat;
+    i2c.frequency(400000);      //  Speed 400000 max.
+    class   MPL3115A2   baro    ;
+    int q;      //  Note address bits 3-1 to match addr pins on 24LC16 memory device
+    for (int i = 0; i < 255; i += 2)    {   //  Search for devices at all possible i2c addresses
+        i2c.start();
+        wait_ms (1);
+        q = i2c.write(i);   //  may return error code 2 when no start issued
+        switch  (q) {
+            case    ACK:
+                pc.printf   ("I2C device found at 0x%x\r\n", i);
+            case    NAK:      //  Device not seen at this address
+                break;
+            case    2:      //  write reports timeout
+                pc.printf   ("I2C Timeout at addr %2x\r\n", i);
+                break;
+            default:
+                pc.printf   ("Unknown error %d in check_24LC64\r\n", q);
+                break;
+        }
+    }
+    i2c.stop();
+    baro.mode_pres  ();
+    pc.printf   ("baro good flag %s\r\n", baro.good ? "true":"false");
+    bool    rv;
+    q = -3;
+    while(1) {
+        q++;
+        if  (q == 0)    baro.reset_zero_inHg();
+        myled = 1; // LED is ON
+        wait(0.3); // 200 ms
+//        pc.printf   ("busy_check %s\r\n", baro.busy_check() ? "true":"false");
+        myled = 0; // LED is OFF
+        wait(0.8); // 1 sec
+//        pc.printf   ("busy_check %s\r\n", baro.busy_check() ? "true":"false");
+        rv  = baro.Update ();
+        Pres = baro.Pressure();
+        Alt = baro.Altitude();
+        inHg = baro.inHg_vacuum();
+        Heat = baro.Temperature();
+const int NOM_PASCALS   = 100000;
+const int HYSTERESIS_PASCALS = 50;
+        if  (Pres > (NOM_PASCALS + HYSTERESIS_PASCALS))
+            pump = 1;
+        if  (Pres < (NOM_PASCALS - HYSTERESIS_PASCALS))
+            pump = 0;
+//        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");
+        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");
+//        rv  = baro.Update ();
+    }
+}
+*/
+#endif