examples: Cleanup C++ examples

Modify the C++ examples to be of same coding standard like C. As a
part of this cleanup, a new LED example is also added.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

examples/c++/i2c.cpp

@@ -0,0 +1,152 @@
+/*
+ * Author: Brendan Le Foll <brendan.le.foll@intel.com>
+ * Author: Thomas Ingleby <thomas.c.ingleby@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.
+ *
+ * Example usage: Outputs X,Y,Z co-ordinates and direction recursively using
+ *                HMC5883L. Press Ctrl+C to exit.
+ *
+ */
+
+/* standard headers */
+#include <iostream>
+#include <math.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* mraa headers */
+#include "mraa/common.hpp"
+#include "mraa/i2c.hpp"
+
+#define MAX_BUFFER_LENGTH 6
+#define HMC5883L_I2C_ADDR 0x1E
+
+// configuration registers
+#define HMC5883L_CONF_REG_A 0x00
+#define HMC5883L_CONF_REG_B 0x01
+
+// mode register
+#define HMC5883L_MODE_REG 0x02
+
+// data register
+#define HMC5883L_X_MSB_REG 0
+#define HMC5883L_X_LSB_REG 1
+#define HMC5883L_Z_MSB_REG 2
+#define HMC5883L_Z_LSB_REG 3
+#define HMC5883L_Y_MSB_REG 4
+#define HMC5883L_Y_LSB_REG 5
+#define DATA_REG_SIZE 6
+
+// status register
+#define HMC5883L_STATUS_REG 0x09
+
+// ID registers
+#define HMC5883L_ID_A_REG 0x0A
+#define HMC5883L_ID_B_REG 0x0B
+#define HMC5883L_ID_C_REG 0x0C
+
+#define HMC5883L_CONT_MODE 0x00
+#define HMC5883L_DATA_REG 0x03
+
+// scales
+#define GA_0_88_REG 0x00 << 5
+#define GA_1_3_REG 0x01 << 5
+#define GA_1_9_REG 0x02 << 5
+#define GA_2_5_REG 0x03 << 5
+#define GA_4_0_REG 0x04 << 5
+#define GA_4_7_REG 0x05 << 5
+#define GA_5_6_REG 0x06 << 5
+#define GA_8_1_REG 0x07 << 5
+
+// digital resolutions
+#define SCALE_0_73_MG 0.73
+#define SCALE_0_92_MG 0.92
+#define SCALE_1_22_MG 1.22
+#define SCALE_1_52_MG 1.52
+#define SCALE_2_27_MG 2.27
+#define SCALE_2_56_MG 2.56
+#define SCALE_3_03_MG 3.03
+#define SCALE_4_35_MG 4.35
+
+#define I2C_BUS 0
+
+volatile sig_atomic_t flag = 1;
+
+void
+sig_handler(int signum)
+{
+    if (signum == SIGINT) {
+        std::cout << "Exiting..." << std::endl;
+        flag = 0;
+    }
+}
+
+int
+main(void)
+{
+    float direction;
+    int16_t x, y, z;
+    uint8_t rx_tx_buf[MAX_BUFFER_LENGTH];
+
+    signal(SIGINT, sig_handler);
+
+    //! [Interesting]
+    mraa::I2c i2c(I2C_BUS);
+
+    i2c.address(HMC5883L_I2C_ADDR);
+    rx_tx_buf[0] = HMC5883L_CONF_REG_B;
+    rx_tx_buf[1] = GA_1_3_REG;
+    i2c.write(rx_tx_buf, 2);
+
+    i2c.address(HMC5883L_I2C_ADDR);
+    rx_tx_buf[0] = HMC5883L_MODE_REG;
+    rx_tx_buf[1] = HMC5883L_CONT_MODE;
+
+    while (flag) {
+        i2c.address(HMC5883L_I2C_ADDR);
+        i2c.writeByte(HMC5883L_DATA_REG);
+
+        i2c.address(HMC5883L_I2C_ADDR);
+        i2c.read(rx_tx_buf, DATA_REG_SIZE);
+
+        x = (rx_tx_buf[HMC5883L_X_MSB_REG] << 8) | rx_tx_buf[HMC5883L_X_LSB_REG];
+        z = (rx_tx_buf[HMC5883L_Z_MSB_REG] << 8) | rx_tx_buf[HMC5883L_Z_LSB_REG];
+        y = (rx_tx_buf[HMC5883L_Y_MSB_REG] << 8) | rx_tx_buf[HMC5883L_Y_LSB_REG];
+
+        // scale and calculate direction
+        direction = atan2(y * SCALE_0_92_MG, x * SCALE_0_92_MG);
+
+        // check if the signs are reversed
+        if (direction < 0)
+            direction += 2 * M_PI;
+
+        std::cout << "Compass scaled data x : %f, y : %f, z : %f" << x * SCALE_0_92_MG
+                  << y * SCALE_0_92_MG << z * SCALE_0_92_MG << std::endl;
+        std::cout << "Heading : %f" << direction * 180 / M_PI << std::endl;
+
+        sleep(1);
+    }
+    //! [Interesting]
+
+    return EXIT_SUCCESS;
+}