[driver] add AMSYS 5915 pressure sensor driver

src/xpcc/driver/pressure/amsys5915.hpp

@@ -0,0 +1,131 @@
+// coding: utf-8
+/* Copyright (c) 2012, Niklas Hauser
+ * Copyright (c) 2017, Raphael Lehmann
+ * All Rights Reserved.
+ *
+ * The file is part of the xpcc library and is released under the 3-clause BSD
+ * license. See the file `LICENSE` for the full license governing this code.
+ */
+// ----------------------------------------------------------------------------
+
+#ifndef XPCC_AMSYS5915_HPP
+#define XPCC_AMSYS5915_HPP
+
+#include <xpcc/architecture/interface/i2c_device.hpp>
+#include <xpcc/math/utils/endianness.hpp>
+
+namespace xpcc
+{
+
+// forward declaration for friending with amsys5915::Data
+template < typename I2cMaster >
+class Amsys5915;
+
+struct amsys5915
+{
+	struct xpcc_packed
+	Data
+	{
+		template < typename I2cMaster >
+		friend class Amsys5915;
+
+	public:
+		/**
+		 * This method returns the pressure as a normalized float from 0-1.
+		 * You have to scale and offset this according to the specific sensor
+		 * you have.
+		 * So if you have AMS 5915-0010-D, you can measure +10mBar, you need to
+		 * multiply it with 10.0f to get the pressure in mBar.
+		 * If you have AMS 5915-0350-D-B, which can measure ±350mBar you first need to
+		 * subtract 0.5f and then multiply it with 350.0f!
+ 		 */
+		float
+		getPressure()
+		{
+			// mask undefined bits
+			data[0] &= 0b00111111;
+			// Full scale span is 13107, with offset 1638
+			uint16_t *rData = reinterpret_cast<uint16_t*>(data);
+			uint16_t pressure = xpcc::fromBigEndian(*rData) - 1638;
+			return static_cast<float>(pressure) / 13107.f;
+		}
+
+		/**
+		 * This method returns the temperature of the pressure sensor in °C.
+		 */
+		float
+		getTemperature()
+		{
+			uint16_t temperatureRaw = (data[3] >> 5) | (static_cast<uint16_t>(data[2]) << 3);
+			return ((temperatureRaw * 200.f) / 2048.f) - 50.f;
+		}
+	private:
+		// 0: MSB
+		// ..
+		// 3: LSB
+		uint8_t data[4];
+	};
+};
+
+/**
+ * Driver for the AMSYS 5915 differential and absolute pressure sensors.
+ *
+ * The device runs a cyclic program, which will store a corrected pressure value with
+ * 12 bit resolution about every 500 μs within the output registers of the internal ASIC.
+ * 
+ * Datasheet: http://www.amsys.de/sheets/amsys.de.ams5915.pdf
+ *
+ * @ingroup driver_pressure
+ * @author	Raphael Lehman, Niklas Hauser
+ */
+template < typename I2cMaster >
+class Amsys5915 : public amsys5915, public xpcc::I2cDevice<I2cMaster, 1, I2cReadTransaction>
+{
+public:
+	/**
+	 * @param	data	a amsys5915::Data object
+	 * @bug The address of the sensor is by factory default set to 0x28.
+	 *      This means you cannot use two AMSYS 5915 sensors on the same bus!
+	 *      You have to use a MUX or two seperate I2C busses.
+	 */
+	Amsys5915(Data &data)
+	:	I2cDevice<I2cMaster,1,I2cReadTransaction>(0x28), data(data)
+	{
+		this->transaction.configureRead(data.data, 4);
+	}
+
+	/// pings the sensor
+	xpcc::ResumableResult<bool>
+	ping()
+	{
+		RF_BEGIN();
+
+		RF_WAIT_UNTIL(this->transaction.configurePing() and this->startTransaction());
+
+		RF_WAIT_WHILE( this->isTransactionRunning() );
+
+		this->transaction.configureRead(data.data, 4);
+
+		RF_END_RETURN( this->wasTransactionSuccessful() );
+	}
+
+	/// reads the Pressure registers and buffers the results
+	inline xpcc::ResumableResult<bool>
+	readPressure()
+	{
+		return this->runTransaction();
+	}
+
+public:
+	/// Get the data object for this sensor.
+	inline Data&
+	getData()
+	{ return data; }
+
+private:
+	Data &data;
+};
+
+}	// namespace xpcc
+
+#endif // XPCC_AMSYS5915_HPP