max31855: add sensor and documentation on creation of a UPM sensor

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/max31855/CMakeLists.txt

@@ -0,0 +1,5 @@
+set (libname "max31855")
+set (libdescription "K type thermistor amplifier")
+set (module_src ${libname}.cxx)
+set (module_h ${libname}.h)
+upm_module_init()

src/max31855/jsupm_max31855.i

@@ -0,0 +1,9 @@
+//! [Interesting]
+%module jsupm_max31855
+
+%{
+    #include "max31855.h"
+%}
+
+%include "max31855.h"
+//! [Interesting]

src/max31855/max31855.cxx

@@ -0,0 +1,103 @@
+/*
+ * Author: Brendan Le Foll <brendan.le.foll@intel.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * 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.
+ */
+
+#include <iostream>
+#include <unistd.h>
+#include <stdlib.h>
+#include <functional>
+#include <string.h>
+
+#include "max31855.h"
+
+using namespace upm;
+
+//! [Constructor]
+MAX31855::MAX31855(int bus, int cs)
+{
+    // initialise chip select as a normal gpio
+    m_gpio = maa_gpio_init(cs);
+    maa_gpio_dir(m_gpio, MAA_GPIO_OUT);
+
+    // initialise the spi bus with a 2Mhz clock
+    m_sensor = maa_spi_init(bus);
+    maa_spi_frequency(m_sensor, 2000000);
+}
+//! [Constructor]
+
+//! [Destructor]
+MAX31855::~MAX31855()
+{
+    // close both m_sensor & m_gpio cleanly
+    maa_result_t error;
+    error = maa_spi_stop(m_sensor);
+    if (error != MAA_SUCCESS) {
+        maa_result_print(error);
+    }
+    error = maa_gpio_close(m_gpio);
+    if (error != MAA_SUCCESS) {
+        maa_result_print(error);
+    }
+}
+//! [Destructor]
+
+double
+MAX31855::getTemp()
+{
+//! [spi]
+    // set chip select low
+    maa_gpio_write(m_gpio, 0);
+
+    uint8_t buf[4];
+
+    // set our input buffer to 0, this is clean but not required
+    memset(buf, 0, sizeof(uint8_t)*4);
+
+    // Write buffer to the spi slave
+    uint8_t* x = maa_spi_write_buf(m_sensor, buf, 4);
+//! [spi]
+
+//! [conversion]
+    // Endian correct way of making our char array into an 32bit int
+    int32_t temp = (x[0] << 24) | (x[1] << 16) | (x[2] << 8) | x[3];;
+
+    // maa_spi_write_buf does not free the return buffer
+    free(x);
+
+    if (temp & 0x7) {
+        std::cerr << "Something went very wrong!" << std::endl;
+    }
+
+    // scrap all the data we dont care about
+    temp >>= 18;
+
+    // LSB = 0.25 degrees C
+    double c = (double) temp;
+    c *= 0.25;
+//! [conversion]
+
+    // set chip select high
+    maa_gpio_write(m_gpio, 1);
+
+    return c;
+}

src/max31855/max31855.h

@@ -0,0 +1,69 @@
+/*
+ * Author: Brendan Le Foll <brendan.le.foll@intel.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * 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.
+ */
+#pragma once
+
+#include <string>
+#include <maa/spi.h>
+#include <maa/gpio.h>
+
+namespace upm {
+
+/**
+ * @brief C++ API for MAX31855
+ *
+ * This file defines the max31855 SPI sensor
+ *
+ * @snippet examples/max31855.cxx Interesting
+ *
+ */
+ //! [Interesting]
+class MAX31855 {
+    public:
+        /**
+         * Instanciates a MAX31855 object
+         *
+         * @param bus The spi bus to use
+         * @param cs The chip select pin
+         */
+        MAX31855(int bus, int cs);
+
+        /**
+         * MAX31855 object destructor
+         */
+        ~MAX31855();
+
+        /**
+         * Get the distance from the sensor
+         *
+         * @return value in degrees celcius
+         */
+        double getTemp();
+
+    private:
+        maa_spi_context m_sensor;
+        maa_gpio_context m_gpio;
+};
+//! [Interesting]
+
+}

src/max31855/pyupm_max31855.i

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+%module pyupm_max31855
+
+%include "stdint.i"
+
+%feature("autodoc", "3");
+
+%include "max31855.h"
+%{
+    #include "max31855.h"
+%}