Add 2 I2C port example

Author: Nathan Seidle

libraries/Examples/examples/Advanced/Additional_I2C_Ports/Additional_I2C_Ports.ino

@@ -0,0 +1,68 @@
+/*
+  Making more I2C ports on the Artemis
+  By: Nathan Seidle
+  SparkFun Electronics
+  Date: June 21, 2019
+  License: MIT. See license file for more information but you can
+  basically do whatever you want with this code.
+
+  This example shows how to add a 2nd (or 3rd) I2C bus to an Artemis carrier board.
+
+  The key to success is that when the SPIClass or TwoWire objects above are constructed they don't actually 
+  change any of the Special Function Registers (SFRs) in the Apollo3. That all happens when you use the .begin()
+  method. This way it is acceptable to define as many different TwoWire or SPIClass objects as you want at one
+  time using only one IOMaster instance. However it is *not* well-characterized how it will perform if you try 
+  to 'begin' more than one. 
+
+  For this example, you'll need:
+  BlackBoard Artemis (or any Artemis board): https://www.sparkfun.com/products/15332
+  Qwiic Accel: https://www.sparkfun.com/products/14587
+  Qwiic Breadboard cable: https://www.sparkfun.com/products/14425
+
+  Hardware Connections:
+  Connect the Qwiic cable to the Accel
+  Plug the male pins into the following pins on the BlackBoard Artemis:
+    Red -> 3.3V
+    Black -> GND
+    Yellow -> SCK
+    Blue -> MISO
+*/
+
+#include <Wire.h>
+
+//Create a TwoWire object that uses a given IOMaster
+TwoWire myWire(0); //Will use pads 5/6, pins labeled SCK/MISO on BlackBoard Artemis
+//TwoWire myWire(1); //Will use pads 8/9
+//TwoWire myWire(2); //Will use pads 25/27, pins labeled D6/RX1 on BlackBoard Artemis
+//TwoWire myWire(3); //Will use pads 42/43
+//TwoWire myWire(4); //Will use pads 39/40, pins labeled SCL/SDA on BlackBoard Artemis
+//TwoWire myWire(5); //Will use pads 48/49, pins labeled TX0/RX0 on BlackBoard Artemis
+
+#include "SparkFun_MMA8452Q.h"    // Click here to get the library: http://librarymanager/All#SparkFun_MMA8452Q
+MMA8452Q accel;                   // Create instance of the MMA8452 class
+
+void setup() {
+  Serial.begin(9600);
+  Serial.println("MMA8452Q on non-standard I2C port!");
+
+  myWire.begin();
+
+  //Here's the next trick. You need to pass this Wire port to your library.
+  //SparkFun libraries allow any Wire port to be passed in. Other folk's libraries may not do this.
+  if (accel.begin(myWire) == false) {
+    Serial.println("Not Connected. Please check connections and read the hookup guide.");
+    while (1);
+  }
+}
+
+void loop() {
+  if (accel.available()) {      // Wait for new data from accelerometer
+    // Acceleration of x, y, and z directions in g units
+    Serial.print(accel.getCalculatedX(), 3);
+    Serial.print("\t");
+    Serial.print(accel.getCalculatedY(), 3);
+    Serial.print("\t");
+    Serial.print(accel.getCalculatedZ(), 3);
+    Serial.println();
+  }
+}