Diff: MS5607Base.h

Revision:

0:5760862143d1

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MS5607Base.h	Tue Jul 03 08:57:57 2012 +0000
@@ -0,0 +1,121 @@
+/*
+Copyright (c) 2012, Senio Networks, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+
+#ifndef MS5607_BASE_H
+#define MS5607_BASE_H
+
+class MS5607Base {
+public:
+    void printCoefficients() {
+        printf("%d, %d, %d, %d, %d, %d\n", c1, c2, c3, c4, c5, c6);
+    }
+
+    int getRawTemperature() {
+        return readADC(ADC_D2 | OSR_4096);
+    }
+
+    int getRawPressure() {
+        return readADC(ADC_D1 | OSR_4096);
+    }
+
+    float getTemperature() {
+        int dT = getRawTemperature() - (c5 << 8);
+        int temp = 2000 + ((dT * c6) >> 23);
+        
+        // 2nd order temperature compensation
+        if (temp < 2000) {
+            int t2 = (int64_t) dT * dT >> 31;
+            temp -= t2;
+        }
+
+        return float(temp) / 100;
+    }
+
+    float getPressure() {
+        int dT = getRawTemperature() - (c5 << 8);
+        int temp = 2000 + ((dT * c6) >> 23);
+        int64_t off = ((int64_t) c2 << 17) + ((int64_t) dT * c4 >> 6);
+        int64_t sens = ((int64_t) c1 << 16) + ((int64_t) dT * c3 >> 7);
+
+        // 2nd order temperature compensation
+        if (temp < 2000) {
+            int64_t off2 = (int64_t) 61 * (temp - 2000) * (temp - 2000) >> 4;
+            int64_t sens2 = (int64_t) 2 * (temp - 2000) * (temp - 2000);
+            if (temp < -1500) {
+                off2 += (int64_t) 15 * (temp + 1500) * (temp + 1500);
+                sens2 += (int64_t) 8 * (temp + 1500) * (temp + 1500);
+            }
+            off -= off2;
+            sens -= sens2;
+        }
+
+        return float((((int64_t) getRawPressure() * sens >> 21) - off) >> 15);
+    }
+
+    float getAltitude(int presssure = 0) {
+        return toAltitude(presssure ? presssure : (int) getPressure());
+    }
+
+protected:
+    int32_t c1, c2, c3, c4, c5, c6;
+
+    enum {
+        RESET     = 0x1E,
+        ADC_READ  = 0x00,
+        ADC_CONV  = 0x40,
+        ADC_D1    = 0x00,
+        ADC_D2    = 0x10,
+        OSR_256   = 0x00,
+        OSR_512   = 0x02,
+        OSR_1024  = 0x04,
+        OSR_2048  = 0x06,
+        OSR_4096  = 0x08,
+        PROM_READ = 0xA0
+    };
+
+    virtual void writeCommand(int command, int ms = 0) = 0;
+    virtual int readPROM(int address) = 0;
+    virtual int readADC(int command) = 0;
+
+    void init() {
+        writeCommand(RESET, 3);
+        c1 = readPROM(1);
+        c2 = readPROM(2);
+        c3 = readPROM(3);
+        c4 = readPROM(4);
+        c5 = readPROM(5);
+        c6 = readPROM(6);
+    }
+
+    float toAltitude(int pressure) {
+        // Ref. 29124-AltimeterAppNote1.pdf
+        const float R = 287.052; // specific gas constant R*/M0
+        const float g = 9.80665; // standard gravity 
+        const float t_grad = 0.0065; // gradient of temperature
+        const float t0 = 273.15 + 15; // temperature at 0 altitude
+        const float p0 = 101325; // pressure at 0 altitude
+
+        return t0 / t_grad * (1 - exp((t_grad * R / g) * log(pressure / p0)));
+    }
+};
+
+#endif
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