Low Level: Serial Ports

The Serial_LCD library can use three kinds of serial port:

• hardware,
  
• software,
  
• and I²C.

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Arduino

• hardware: Serial (pins 0 & 1)
  
• software: with library NewSoftSerial release 11 for Arduino 23 or SoftwareSerial for Arduino 1.0 
  
• I²C: (pins 4 & 5) with library I2C_Serial

chipKIT

• hardware: Serial (pins 0 & 1) or Serial1 (pins 39 & 40)
  
• software: not available
  
• I²C: (pins 4 & 5) with library I2C_Serial

Wiring

• hardware: Serial (port 0 pins 0 & 1) or Serial1 (port 0 pins 2 & 3)
  
• software: with library NewSoftSerial or SotfwareSerial
  
• I²C: (port 1 pins 6 & 7) with library I2C_Serial

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The ProxySerial.h library is a hardware abstraction library that manages the different kinds of serial ports and allows portability.

Hardware Serial Port

The Arduino Uno features one hardware serial port, mainly used for debugging. 

But other boards like the Arduino mega2560, the Wiring S and the chipKIT Uno32, have additional ports.

On the right, an example with port Serial1.

Maximum speeds are:

• 38400bps for Arduino mega2560
  
• 57600 and even 115200bps for chipKIT Uno32

// Include
#include "ProxySerial.h"
#include "Serial_LCD.h"

// Serial port choice
#define mySerial Serial1
ProxySerial myPort(&mySerial);
Serial_LCD myLCD( &myPort);
 
// Serial port initialisation
mySerial.begin(9600);
myLCD.begin();

// Serial port speed up
myLCD.setSpeed(38400);
mySerial.begin(38400);

Software Serial Port

The Arduino Uno features one hardware serial port, mainly used for debugging. 

Hence the software serial port brought by NewSoftSerial.h for Arduino 23 or SoftwareSerial.h for Arduino 1.0.

Maximum speeds are:

• 38400bps for Arduino Uno

For Arduino 23, please use the NewSoftSerial release 11 beta and follow instructions provided at Tutorial 2: Playing with Serial Ports.

// Include
#include "SoftwareSerial.h"  // for Arduino 1.0
#include "ProxySerial.h"
#include "Serial_LCD.h"

// Serial port choice
SoftwareSerial mySerial(2, 3); // RX, TX pins
ProxySerial myPort(&mySerial);
Serial_LCD myLCD( &myPort);
 
// Serial port initialisation
mySerial.begin(9600);
myLCD.begin();

// Serial port speed up
myLCD.setSpeed(38400);
mySerial.begin(38400);

I²C Serial Port

I²C to serial port bridge provides an extra serial port right on the I²C bus.

The specific I2C_Serial library is required.

Just proceed as shown in the example on the right:

Maximum speeds are:

• 38400, 57600 and even 115200bps, depending on how many devices are plugged into the I²C bus.

// Include
#include "I2C_Serial.h"
#include "ProxySerial.h"
#include "Serial_LCD.h"

// Serial port choice
I2C_Serial mySerial;
ProxySerial myPort(&mySerial);
Serial_LCD myLCD( &myPort);
 
// Serial port initialisation
mySerial.begin(9600);
myLCD.begin();

// Serial port speed up
myLCD.setSpeed(38400);
mySerial.begin(38400);

Final Recommendation

Remember the LCD board is powered by a 12 MHz controller.

So it works fine with a 16 MHz Arduino board but issues may arise with the over-speedy 80 MHz chipKIT Uno32. 

While working with the chipKIT Uno32, consider including delay() in your code when appropriate, and specify a higher value for the securityDelay parameter. 

Learn more about Overload Protection.

#define securityDelay 3