added support for custom HW I2C on Mbed targets

Author: Laurence Bank

README.md

@@ -4,8 +4,9 @@ Copyright (c) 2018 BitBank Software, Inc.
 Written by Larry Bank ([email protected])
 Project started 10/12/2018
 
-The purpose of this code is to provide a simple C library which can bit-bang
-the I2C protocol on any 2 GPIO pins on any system. The I2C protocol doesn't
+The purpose of this code is to provide a simple C library which can manage I2c
+in a consistent way across different platforms, in addition to providing
+software bit-bang of the protocol on any 2 GPIO pins. The I2C protocol doesn't
 require any special functionality of the pins beyond standard GPIO features.
 The reason I wrote it was for getting easy access to I2C devices on
 various microcontrollers that don't necessarily have exposed I2C interfaces.

examples/I2C_Detector/I2C_Detector.ino

@@ -38,17 +38,17 @@
 
 // Arbitrary pins I used for testing with an ATmega328p
 // Define as -1, -1 to use the Wire library over the default I2C interface
-//#define SDA_PIN -1
-//#define SCL_PIN -1
+#define SDA_PIN 13
+#define SCL_PIN 14
 // M5Stack Atom Grove connector pin assignments
 //#define SDA_PIN 32 
 //#define SCL_PIN 26
 // M5Stack Atom internal I2C connected to the IMU
 //#define SDA_PIN 25
 //#define SCL_PIN 21
 // M5Stack Core2 internal I2C
-#define SDA_PIN 21
-#define SCL_PIN 22
+//#define SDA_PIN 21
+//#define SCL_PIN 22
 //
 // If you don't need the explicit device names displayed, disable this code by
 // commenting out the next line
@@ -66,8 +66,10 @@ BBI2C bbi2c;
 
 void setup() {
   Serial.begin(115200);
+  while (!Serial) {};
+  Serial.println("I2C Scan Demo");
   memset(&bbi2c, 0, sizeof(bbi2c));
-  bbi2c.bWire = 0; // use bit bang, not wire library
+  bbi2c.bWire = 1; // use bit bang, not wire library
   bbi2c.iSDA = SDA_PIN;
   bbi2c.iSCL = SCL_PIN;
   I2CInit(&bbi2c, 100000L);

library.properties

@@ -1,5 +1,5 @@
 name=BitBang_I2C
-version=2.1.5
+version=2.2.0
 author=Larry Bank <[email protected]>
 maintainer=Larry Bank <[email protected]>
 sentence=Bit-bang the I2C protocol on any 2 GPIO pins on any system.