galileo: Add I2C master example

This patch adds an example application that shows how to use I2C driver
APIs to communicate with LSM9DS0 sensor. At every 5 seconds, the
application reads the "Who Am I" register from gyroscope sensor and
prints if the register value matches the expected value.

examples/galileo/Makefile

@@ -1,4 +1,6 @@
-KNOWN_EXAMPLES = gpio-output
+TARGET=galileo
+
+KNOWN_EXAMPLES = gpio-output i2c-LSM9DS0
 
 ifneq ($(filter $(EXAMPLE),$(KNOWN_EXAMPLES)),)
   CONTIKI_PROJECT = $(EXAMPLE)

examples/galileo/README

@@ -23,3 +23,33 @@ state at every half second.
 For a visual effect, you should wire shield pin IO1 to a led in a protoboard.
 Once the application is running, you should see a blinking LED.
 
+=======
+= I2C =
+=======
+
+I2C LSM9DS0
+===========
+This application shows how to use I2C driver APIs to configure I2C Master
+controller and communicate with LSM9DS0 sensor. At every 5 seconds, the
+application reads the "who am I" register from gyroscope sensor and prints if
+the register value matches the expected value described in the spec [1].
+
+According to the sensor spec, to read the value in "who am I" register, we
+should first perform an i2c write operation to select the register we want
+to read from and then we perform the i2c read operation to actually read
+the register contents.
+
+The wiring setup is as follows (left column from Galileo and right column from LSM9DS0):
+- 3.3v and Vin
+- GND  and GND
+- GND  and SDOG
+- 3.3v and CSG
+- SDA  and SDA
+- SCL  and SCL
+
+==============
+= References =
+==============
+
+[1] http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/DM00087365.pdf
+

examples/galileo/i2c-LSM9DS0.c

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2015, Intel Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "contiki.h"
+#include "sys/ctimer.h"
+
+#include "i2c.h"
+
+#define LSM9DS0_I2C_ADDR 0x6A
+#define WHO_AM_I_ADDR    0x0F
+#define WHO_AM_I_ANSWER  0xD4
+
+static uint8_t tx_data = WHO_AM_I_ADDR;
+static uint8_t rx_data = 0;
+static struct ctimer timer;
+static struct quarkX1000_i2c_config cfg;
+
+PROCESS(i2c_lsm9ds0_process, "I2C LSM9DS0 Who Am I Process");
+AUTOSTART_PROCESSES(&i2c_lsm9ds0_process);
+/*---------------------------------------------------------------------------*/
+static void
+rx(void)
+{
+  if (rx_data == WHO_AM_I_ANSWER)
+    printf("Who am I register value match!\n");
+  else
+    printf("Who am I register value DOESN'T match! %u\n", rx_data);
+}
+/*---------------------------------------------------------------------------*/
+static void
+tx(void)
+{
+  rx_data = 0;
+
+  quarkX1000_i2c_read(&rx_data, sizeof(rx_data), LSM9DS0_I2C_ADDR);
+}
+/*---------------------------------------------------------------------------*/
+static void
+err(void)
+{
+  printf("Something went wrong. err() callback has been called.\n");
+}
+/*---------------------------------------------------------------------------*/
+static void
+timeout(void *data)
+{
+  quarkX1000_i2c_write(&tx_data, sizeof(tx_data), LSM9DS0_I2C_ADDR);
+
+  ctimer_reset(&timer);
+}
+/*---------------------------------------------------------------------------*/
+PROCESS_THREAD(i2c_lsm9ds0_process, ev, data)
+{
+  PROCESS_BEGIN();
+
+  cfg.speed = QUARKX1000_I2C_SPEED_STANDARD;
+  cfg.addressing_mode = QUARKX1000_I2C_ADDR_MODE_7BIT;
+  cfg.cb_rx = rx;
+  cfg.cb_tx = tx;
+  cfg.cb_err = err;
+
+  quarkX1000_i2c_init();
+  quarkX1000_i2c_configure(&cfg);
+
+  ctimer_set(&timer, CLOCK_SECOND * 5, timeout, NULL);
+
+  printf("I2C LSM9DS0 example is running\n");
+
+  PROCESS_YIELD();
+
+  PROCESS_END();
+}