LCD Support

[rmurphey]

@haugstrup has a proof of concept here -- wanted to see if we can move the discussion to here!

[haugstrup]

Hardware resources

• http://en.wikipedia.org/wiki/Hitachi_HD44780_LCD_controller
• http://lcd-linux.sourceforge.net/pdfdocs/lcd1.pdf
• http://lcd-linux.sourceforge.net/pdfdocs/lcd2.pdf

Software resources

• http://arduino.cc/en/Reference/LiquidCrystal/
• https://github.com/arduino/Arduino/tree/master/libraries/LiquidCrystal

[haugstrup]

Some random documentation so I don't have to store it in my brain:

One thing I'm not sure how to handle best is the character mapping. The character map for the LCD is 'almost' US-ASCII for the first 127 code points. There are the following changes:

• 92 is a Yen symbol instead of backslash
• 126 is a right-arrow instead of a tilde
• 127 is a left-arrow instead of del

Additionally there are prettier versions of g, j, p, q and y available at code points 231, 234, 240, 241, 249. These go below the baseline and will only fit on a 5x10 pixel display, but they should be used instead of the ASCII code points for those letters if available.

Input should be validated before being sent to the LCD so only 'good' code points are being sent. Otherwise I think people can end up in strange situations.

[rmurphey]

Wanted to make a list of the things we should incorporate:

• make command method use write4Bits or write8Bits methods (in-progress)
• configurable four-bit, eight-bit mode
• configurable 1/2 lines
• configurable 5x8, 5x10 dots
• display, noDisplay methods
• setCursor method
• cursor, noCursor methods
• blink, noBlink methods
• leftToRight, rightToLeft
• scrollDisplayLeft, scrollDisplayRight
• autoscroll, noAutoscroll

These should be straightforward to implement based on https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp.

[haugstrup]

A few more

• Configure number of columns (16, 20, 40 whatever)
• Convenience method for writing out a single line of text to the display