Make I2C address configurable for HD44780 LCD variations

Also add a basic README with some pointers on how to connect and configure the LCDs

Conf.cpp

@@ -130,6 +130,7 @@ m_tftSerialBrightness(50U),
 m_hd44780Rows(2U),
 m_hd44780Columns(16U),
 m_hd44780Pins(),
+m_hd44780i2cAddress,
 m_hd44780PWM(false),
 m_hd44780PWMPin(),
 m_hd44780PWMBright(),
@@ -438,6 +439,8 @@ bool CConf::read()
 			m_hd44780Rows = (unsigned int)::atoi(value);
 		else if (::strcmp(key, "Columns") == 0)
 			m_hd44780Columns = (unsigned int)::atoi(value);
+		else if (::strcmp(key, "I2CAddress") == 0)
+			m_hd44780i2cAddress = value;
 		else if (::strcmp(key, "PWM") == 0)
 			m_hd44780PWM = ::atoi(value) == 1;
 		else if (::strcmp(key, "PWMPin") == 0)
@@ -889,6 +892,11 @@ std::vector<unsigned int> CConf::getHD44780Pins() const
 	return m_hd44780Pins;
 }
 
+std::string CConf::getHD44780i2cAddress() const
+{
+  return m_hd44780i2cAddress;
+}
+
 bool CConf::getHD44780PWM() const
 {
 	return m_hd44780PWM;

Conf.h

@@ -137,6 +137,7 @@ class CConf
   unsigned int getHD44780Rows() const;
   unsigned int getHD44780Columns() const;
   std::vector<unsigned int> getHD44780Pins() const;
+	std::string  getHD44780i2cAddress() const;
   bool         getHD44780PWM() const;
   unsigned int getHD44780PWMPin() const;
   unsigned int getHD44780PWMBright() const;
@@ -252,6 +253,7 @@ class CConf
   unsigned int m_hd44780Rows;
   unsigned int m_hd44780Columns;
   std::vector<unsigned int> m_hd44780Pins;
+	std::string  m_hd44780i2cAddress;
   bool         m_hd44780PWM;
   unsigned int m_hd44780PWMPin;
   unsigned int m_hd44780PWMBright;

HD44780.cpp

@@ -36,7 +36,7 @@ char        m_buffer2[128U];
 char        m_buffer3[128U];
 char        m_buffer4[128U];
 
-CHD44780::CHD44780(unsigned int rows, unsigned int cols, const std::string& callsign, unsigned int dmrid, const std::vector<unsigned int>& pins, bool pwm, unsigned int pwmPin, unsigned int pwmBright, unsigned int pwmDim, bool displayClock, bool utc, bool duplex) :
+CHD44780::CHD44780(unsigned int rows, unsigned int cols, const std::string& callsign, unsigned int dmrid, const std::vector<unsigned int>& pins, const std::string& i2cAddress, bool pwm, unsigned int pwmPin, unsigned int pwmBright, unsigned int pwmDim, bool displayClock, bool utc, bool duplex) :
 CDisplay(),
 m_rows(rows),
 m_cols(cols),
@@ -48,6 +48,7 @@ m_d0(pins.at(2U)),
 m_d1(pins.at(3U)),
 m_d2(pins.at(4U)),
 m_d3(pins.at(5U)),
+m_i2cAddress(i2cAddress),
 m_pwm(pwm),
 m_pwmPin(pwmPin),
 m_pwmBright(pwmBright),
@@ -239,7 +240,7 @@ bool CHD44780::open()
 void CHD44780::adafruitLCDSetup()
 {
     // The other control pins are initialised with lcdInit()
-    ::mcp23017Setup(AF_BASE, MCP23017);
+    ::mcp23017Setup(AF_BASE, m_i2caddress);
 
     // Backlight LEDs    
     ::pinMode(AF_RED,   OUTPUT);
@@ -311,7 +312,7 @@ void CHD44780::adafruitLCDColour(ADAFRUIT_COLOUR colour)
 void CHD44780::pcf8574LCDSetup()
 {
 	// Initalize PFC8574
-	::pcf8574Setup(AF_BASE, PCF8574);
+	::pcf8574Setup(AF_BASE, m_i2cAddress);
 
 	// Turn on backlight
 	::pinMode (AF_BL, OUTPUT);

HD44780.h

@@ -67,7 +67,7 @@ enum ADAFRUIT_COLOUR {
 #define AF_ON     LOW
 #define AF_OFF    HIGH
 
-#define MCP23017  0x20
+// #define MCP23017  0x20
 #endif
 
 // Define for HD44780 connected via a PCF8574 GPIO extender
@@ -83,13 +83,13 @@ enum ADAFRUIT_COLOUR {
 #define AF_D2     (AF_BASE +  6)
 #define AF_D3     (AF_BASE +  7)
 
-#define PCF8574		0x27
+// #define PCF8574		0x27
 #endif
 
 class CHD44780 : public CDisplay
 {
 public:
-  CHD44780(unsigned int rows, unsigned int cols, const std::string& callsign, unsigned int dmrid, const std::vector<unsigned int>& pins, bool pwm, unsigned int pwmPin, unsigned int pwmBright, unsigned int pwmDim, bool displayClock, bool utc, bool duplex);
+  CHD44780(unsigned int rows, unsigned int cols, const std::string& callsign, unsigned int dmrid, const std::vector<unsigned int>& pins, const std::string& i2cAddress, bool pwm, unsigned int pwmPin, unsigned int pwmBright, unsigned int pwmDim, bool displayClock, bool utc, bool duplex);
   virtual ~CHD44780();
 
   virtual bool open();
@@ -123,6 +123,7 @@ class CHD44780 : public CDisplay
 	unsigned int m_d1;
 	unsigned int m_d2;
 	unsigned int m_d3;
+	std::string  m_i2cAddress;
 	bool         m_pwm;
 	unsigned int m_pwmPin;
 	unsigned int m_pwmBright;

MMDVM.ini

@@ -107,15 +107,20 @@ Brightness=50
 [HD44780]
 Rows=2
 Columns=16
+
+# For basic HD44780 displays (4-bit connection)
 # rs, strb, d0, d1, d2, d3
-# For basic HD44780 displays
 Pins=11,10,0,1,2,3
 
+# Device address for I2C
+I2CAddress=0x20
+
 # PWM backlight
 PWM=0
 PWMPin=21
 PWMBright=100
 PWMDim=16
+
 DisplayClock=1
 UTC=0
 

MMDVMHost.cpp

@@ -875,6 +875,7 @@ void CMMDVMHost::createDisplay()
 		unsigned int rows              = m_conf.getHD44780Rows();
 		unsigned int columns           = m_conf.getHD44780Columns();
 		std::vector<unsigned int> pins = m_conf.getHD44780Pins();
+		std::string i2cAddress         = m_conf.getHD44780i2cAddress();
 		bool pwm                       = m_conf.getHD44780PWM();
 		unsigned int pwmPin            = m_conf.getHD44780PWMPin();
 		unsigned int pwmBright         = m_conf.getHD44780PWMBright();
@@ -898,7 +899,7 @@ void CMMDVMHost::createDisplay()
 			if (displayClock)
 				LogInfo("    Display UTC: %s", utc ? "yes" : "no");
 
-			m_display = new CHD44780(rows, columns, m_callsign, dmrid, pins, pwm, pwmPin, pwmBright, pwmDim, displayClock, utc, m_duplex);
+			m_display = new CHD44780(rows, columns, m_callsign, dmrid, pins, i2cAddress, pwm, pwmPin, pwmBright, pwmDim, displayClock, utc, m_duplex);
 		}
 #endif
 #if defined(OLED)

README.HD44780

@@ -0,0 +1,46 @@
+                             - HD44780 LCD SUPPORT -
+
+Support for the HD44780 LCD is via the wiringPi library available at
+http://wiringpi.com/download-and-install/ which must be installed in all cases.
+
+The HD44780 in 4-bit mode is probably the most common connection method and
+wiring details can be found at http://wiringpi.com/dev-lib/lcd-library/
+
+To compile MMDVMHost with support for the HD44780 use the following commands.
+
+# cp Makefile.Pi.HD44780 Makefile
+# make clean
+# make
+
+Other HD44780 variations exist that connect via I2C. Support is also via 
+wiringPi, but to compile for each I2C device requires a different Makefile 
+depending on the IC attached to the LCD.
+
+                           - ADAFRUIT RGB LCD SHIELD -
+
+The Adafruit RGB LCD Shield is available from https://www.adafruit.com/product/714
+I2C is  via the MCP23017 IC and is enabled with Makefile.Pi.Adafruit. The 
+I2C device address in MMDVM.ini should be set to 0x20.
+
+                                 - PCF8574 IC -
+
+HD44780 LCDs connected via a PCF8574 Remote 8-Bit I/O Expander are available on
+eBay for very little money! This IC uses Makefile.Pi.PCF8574 and the I2C
+device address should be set to 0x27.
+
+                                   - BEWARE -
+
+        The I2C device address can be manually configured on some devices! 
+
+                       - CHECK YOUR ACTUAL DEVICE ADDRESS -
+
+More information on configuring and using I2C on the RPi including how to probe
+the I2C bus for device addresses can be found at
+https://learn.sparkfun.com/tutorials/raspberry-pi-spi-and-i2c-tutorial#i2c-on-pi
+
+                             - PWM BACKLIGHT CONTROL - 
+
+Whilst connected in 4-bit mode or via the PCF8574 IC, the LED backlight can be
+wired for control via PWM.  Connect the backlight +ve pin to any spare GPIO pin 
+and configure MMDVM.ini as appropriate. By default, wiringPi pin 21 is 
+configured.