Diff: MPL115A2.h

Revision:

0:4df6d69700fa

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MPL115A2.h	Tue Apr 26 11:26:18 2011 +0000
@@ -0,0 +1,107 @@
+#ifndef MPL115A2
+#define MPL115A
+
+#include "mbed.h"
+
+/**
+ * MPL115A2 (I2C) pressure sensor
+ */
+
+class MPL115A2 {
+public:
+    /**
+    * Create an MPL115A(I2C) interface with specified pins
+    *
+    * @param PinName sda SDA pin (default = p9)
+    * @param PinName scl SCL pin (default = p10)
+    */
+    MPL115A2(PinName sda = p9, PinName scl = p10) : i2c(sda, scl) {
+    }
+
+    /**
+    * Read current pressure and/or temperature
+    *
+    * @param puressure pointer to an int area to receive pressure
+    * @param temperature pointer to a float area to receive temperature
+    *
+    * @returns 0 (success), or -1 (I2C error)
+    */
+
+    int read(int *pressure, float *temperature) {
+        const char id = 0x60 << 1;
+        char cmd[2] = {0x12, 0x01}; // read both
+        char buf[16];
+
+        if (i2c.write(id, cmd, 2) != 0)
+            return -1;
+
+        wait_ms(1);
+
+        cmd[0] = 0;
+
+        if (i2c.write(id, cmd, 1, true) != 0)
+            return -1;
+
+        if (i2c.read(id, buf, 16) == 0) {
+            int padc = short((buf[0] << 8 | buf[1]) >> 6);
+            int tadc = short((buf[2] << 8 | buf[3]) >> 6);
+            int a0 = short(buf[4] << 8 | buf[5]);
+            int b1 = short(buf[6] << 8 | buf[7]);
+            int b2 = short(buf[8] << 8 | buf[9]);
+            int c12 = short(buf[10] << 8 | buf[11]);
+            int c11 = short(buf[12] << 8 | buf[13]);
+            int c22 = short(buf[14] << 8 | buf[15]);
+            int pcomp = ((a0 << 10) + b1 * padc + (b2 * tadc >> 1) +
+                         (c11 * padc * padc >> 14) + (c12 * tadc * padc >> 11) + (c22 * tadc * tadc >> 17)) >> 13;
+
+            if (temperature != 0)
+                *temperature = 25.0 - (tadc - 472) / 5.35;
+
+            if (pressure != 0)
+                *pressure = (650 * pcomp + 512) / 1023 + 500;
+
+            return 0;
+        }
+
+        return -1;
+    }
+    
+    /**
+    * Read current pressure
+    *
+    * @returns current pressure (in hPa)
+    */
+    int readPressure() {
+        int pressure;
+        return read(&pressure, 0) == 0 ? pressure : 0;
+    }
+    
+    /**
+    * Read current temperature
+    *
+    * @returns current temperature (in Celcius)
+    */
+    float readTemperature() {
+        float temperature;
+        return read(0, &temperature) == 0 ? temperature : -273.15;
+    }
+
+    /**
+    * Operator shorthand for readPressure()
+    */
+    operator int() {
+        return readPressure();
+    }
+
+    /**
+    * Operator shorthand for readTemperature()
+    */
+    operator float() {
+        return readTemperature();
+    }
+
+private:
+    I2C i2c;
+};
+
+#endif
\ No newline at end of file