Todor Todorov / TFTLCD

This is a port of Henning Kralsen's UTFT library for Arduino/chipKIT to mbed, refactored to make full use of C++ inheritance and access control, in order to reduce work when implementing new drivers and at the same time make the code more readable and easier to maintain. As of now supported are SSD1289 (16-bit interface), HX8340-B (serial interface) and ST7735 (serial interface). Drivers for other controllers will be added as time and resources to acquire the displays to test the code permit.

Dependents:   test SDCard capstone_display capstone_display_2 ... more

TFTLCD Library

NOTE (2013-03-25) Tested with both mbed LPC1768 and Freedom KL25Z. -todor

A TFT LCD driver library, which at the moment provides support for the following display controllers: HX8340-B (serial interface), SSD1289 (16-bit interface), ST7735-R (serial interface), ILI9325/ILI9328 (16-bit interface).

As I am acquiring and testing out new displays, I decided to combine all ported drivers into one library as with the original work done by Henning. However I also had as a goal to make the code maintenance and readability easier/better, so the code has been heavily refactored to make full use of C++ facilities as inheritance and access control. I extracted the common pieces of code into a base class, which every driver inherits and only the controller-specific side is provided in the actual driver - things like initialization, addressing, data transfer, etc.

Another nice extension is that the display's backlight can now be controlled through the driver. Either a simple on/off method of control could be selected, or the brightness can be set through use of PWM (the latter placing some restrictions on which pins can be used for this, as mbed offers hardware PWM on only 6 pins).

I also plan to add support for touch screens as part of the library. The goal is to grow this piece of software into a lightweight graphics widgets library, which can be used to construct control screens with buttons or menus in a speedy and intuitive way.

Changes

2013-07-21

• Fixed the sleep/wake-up functions of the ILI9328 driver.

2013-06-15

• Added driver for ILI9328 (works with ILI9325) controller, 16-bit data bus. Screen rotation works as usual with the TFTLCD library, but for now only RGB565 color depth is working and you can use both 65K and 262K color space with this driver. But for some reason the sleep function is not behaving as expected; I am working on this.
• This is only on my to-do list for now - haven't really had the time yet - but I am going to refactor the library a bit to allow use of GPIO ports for data transfers instead of DigitalOut: faster and cleaner that way. For those who are using it already in a working design and cannot repurpose the pins anymore, the current way it's working will still be available; I am hoping not to tear up the public interfaces of the library (... too much). Anyway, since I am at it, I will also try to add support for multiple bus interfaces to drivers that support it (i.e. both 8bit and 16bit use of ILI932x or SSD1289). Thought this might be a good place to give you guys the heads-up.

2013-01-25

• Replaced all existing fonts from the UTFT library with the free Terminus font. Two different sizes are provided: 8x12 pixels and 16x28 pixels. I found the old fonts not so good looking and then they supported only the ASCII codes in the range 30 (space) to 126 (the tilde ). The 7segment font didn't even implement anything else than the numbers from 0 to 9 - so it was unusable for anything (one couldn't even display the time or date as it lacked the colon [:] or the period [.] or the slash [/] or the space [ ] characters). So I completely revamped the fonts and added Terminus as the new default with its 2 sizes. Further more I added in both sizes most of the characters up to ASCII code 255. For any code not in there, the space character is substituted. In the case, when you already have provided your own fonts, please have a look at the API changes in the files <terminus.h> and <terminus.cpp>: I promise you whatever time you spent designing your own font, it is not wasted; you merely need to add a second array, which describes which ASCII codes are available in your font, and their byte offset in the original character bitmap array; and a struct to tie all parts together and describe the character size. I am sorry for breaking the old API, but you will like the change and new options it brings you. Now you can insert any char above 127 up to code 255 (if available, of course) with its hex representation, e.g displaying the current temperature would look something like 85\xB0 F or 26\xB0 C (the space in between degree and F or C is needed because both F and C are used in hex numbers, so \xB0F is interpreted as ASCII code 2831 instead of ASCII code 176, followed by the temperature scale denomination; if you insist on avoiding the space, you could write 85\xB0\x46 which will be displayed correctly as 85°F). You can either look up the ASCII code you need on Google or Bing, or just look at what's available - how it looks and its hex value - in the comments in <terminus.cpp>.
• Added PWM backlight control. If you intend to use this, please make sure that control pin is either one of p21, p22, p23, p24, p25, or p26, as only they support hardware PWM. Please be aware that the mbed pins do not have much juice behind them, so if your display's backlight requires a lot of current, you are better off interfacing through as small signal transistor or a MOSFET. For the rest please consult the updated Doxygen documentation. NOTE The addition of PWM-controlled backlight will not break your existing code, the new options have default values, which initialize the used driver to behave as prior to PWM. Only if you want to use the new feature, some changes need to be made. The PWM is configured to be 120Hz (period of 8.33 milliseconds), in order to avoid noticeable flicker in the backlight. If in your opinion this value is too fine, then you can reduce the frequency in the LCD constructor in <lcd_base.cpp> by increasing the period value. My recommendation is to avoid frequencies lower than 60Hz.

2012-12-21

• Internal-only changes in the way drivers transmit colors - done to simplify the bitmap drawing routines; client API remains unchanged.

2012-12-12

• Added the driver for the ST7735 display controller.
• Added the RGB18 color mode: choose between 16-bit (65K distinct colors) and 18-bit (262K distinct colors) color space [supported by all drivers]. NOTE This feature requires the image drawing functions to be changed, in order to account for differences between configured display color depth and the color depth of the image. Please review the API docs, in particular the new type bitmap_t and the DrawBitmap functions.
• Changed display rotation to be achieved through the correspondent settings in the respective controller registers: no more software translation between width and height in different display orientations.
• Extended the orientation options: PORTRAIT (top line to 12 o'clock/upright) and LANDSCAPE (top line to 9 o'clock) positions are the old options, PORTRAIT_REV (top line to 6 o'clock/upside-down) and LANDSCAPE_REV (top line to 3 o'clock) are the new orientations.
• Added more pre-defined colors: available now are COLOR_BLACK, COLOR_WHITE, COLOR_RED, COLOR_GREEN, COLOR_BLUE, COLOR_CYAN, COLOR_MAGENTA and COLOR_YELLOW.

TODO

• Finish implementing PWM-controlled backlight (current-sink configuration).
• Add a driver for the HX8352-A controller (ITDB02-3.2WD 16:9 240x400 pixel resolution display).

How to Use

The code is documented, so please review the API docs. There is a simple example to get you started...

--- a/lcd_base.h	Sat Dec 01 23:49:10 2012 +0000
+++ b/lcd_base.h	Sun Dec 02 00:12:43 2012 +0000
@@ -33,9 +33,18 @@
 #include "mbed.h"
 #include "fonts.h"
 
+/** \def HIGH
+ *  \brief User-friendly high pin level designation.
+ */
 #define HIGH        1
+/** \def LOW
+ *  \brief User-friendly low pin level designation.
+ */
 #define LOW         0
 
+/** \def swap( type, a, b )
+ *  \brief Convenience macro to swap two values.
+ */
 #define swap( type, a, b )      { type tmp = ( a ); ( a ) = ( b ); ( b ) = tmp; }
 
 /** \def RGB(r,g,b)
@@ -326,7 +335,7 @@
      * \remarks Commands are controller-specific and this function needs to
      *          be implemented separately for each available controller.
      */
-    virtual void writeCmd( unsigned short cmd ) = 0;
+    virtual void WriteCmd( unsigned short cmd ) = 0;
     
     /** Sends pixel data to the display.
      *
@@ -334,7 +343,7 @@
      * \remarks Sendin data is controller-specific and this function needs to
      *          be implemented separately for each available controller.
      */
-    virtual void writeData( unsigned short data ) = 0;
+    virtual void WriteData( unsigned short data ) = 0;
     
     /** Sends both command and data to the display controller.
      *
@@ -344,7 +353,7 @@
      * \param cmd The display command.
      * \param data The display pixel data.
      */
-    virtual void writeCmdData( unsigned short cmd, unsigned short data );
+    virtual void WriteCmdData( unsigned short cmd, unsigned short data );
     
     /** Assigns a chunk of the display memory to receive data.
      *
@@ -362,16 +371,63 @@
      * \remarks Addressing commands are controller-specific and this function needs to be
      *          implemented separately for each available controller.
      */
-    virtual void setXY( uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2 ) = 0;
+    virtual void SetXY( uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2 ) = 0;
     
     /** Resets the memory address for the next display write operation to the screen origins (0,0).
      */
-    virtual void clearXY( void );
+    virtual void ClearXY( void );
+    
+    /** Draws a horizontal line.
+     *
+     * This is a utility function to draw horizontal-only lines
+     * for reduced code complexity and faster execution.
+     *
+     * \param x X coordinate of the starting point of the line.
+     * \param y Y coordinate of the starting point of the line.
+     * \param len Length of the line.
+     * \param color The color to use to draw the line. By default the global foreground color is used ( -2 ),
+     *              -1 switches to the default background color, or any other RGB-565 color can be used.
+     */
+    virtual void DrawHLine( unsigned short x, unsigned short y, unsigned short len, int color = -2 );
     
-    virtual void drawHLine( unsigned short x, unsigned short y, unsigned short len, int color = -2 );
-    virtual void drawVLine( unsigned short x, unsigned short y, unsigned short len, int color = -2 );
-    virtual void printChar( char c, unsigned short x, unsigned short y, int fgColor = -2, int bgColor = -1 );
-    virtual void rotateChar( char c, unsigned short x, unsigned short y, int pos, int fgColor = -2, int bgColor = -1, unsigned short deg = 0 );
+    /** Draws a vertical line.
+     *
+     * This is a utility function to draw vertical-only lines
+     * for reduced code complexity and faster execution.
+     *
+     * \param x X coordinate of the starting point of the line.
+     * \param y Y coordinate of the starting point of the line.
+     * \param len Height of the line.
+     * \param color The color to use to draw the line. By default the global foreground color is used ( -2 ),
+     *              -1 switches to the default background color, or any other RGB-565 color can be used.
+     */
+    virtual void DrawVLine( unsigned short x, unsigned short y, unsigned short len, int color = -2 );
+    
+    /** Prints a character at the given position and using the given color.
+     *
+     * \param c The character.
+     * \param x X coordinate of the character position.
+     * \param y Y coordinate of the character position.
+     * \param fgColor Foreground color for drawing. By default the global foreground color is used ( -2 ),
+     *                -1 switches to the default background color, or any other RGB-565 color can be used.
+     * \param bgColor Background color for drawing. By default the global background color is used ( -1 ),
+     *                -2 switches to the default foreground color, or any other RGB-565 color can be used.
+     */
+    virtual void PrintChar( char c, unsigned short x, unsigned short y, int fgColor = -2, int bgColor = -1 );
+    
+    /** Prints a character at the given position and using the given color and with the given rotation.
+     *
+     * \param c The character.
+     * \param x X coordinate of the character position.
+     * \param y Y coordinate of the character position.
+     * \param pos Position of the character in the string from which it originates (used to rotate a whole string).
+     * \param fgColor Foreground color for drawing. By default the global foreground color is used ( -2 ),
+     *                -1 switches to the default background color, or any other RGB-565 color can be used.
+     * \param bgColor Background color for drawing. By default the global background color is used ( -1 ),
+     *                -2 switches to the default foreground color, or any other RGB-565 color can be used.
+     * \param deg The angle at which to rotate. 
+     */
+    virtual void RotateChar( char c, unsigned short x, unsigned short y, int pos, int fgColor = -2, int bgColor = -1, unsigned short deg = 0 );
 
 protected:
     unsigned short _disp_width, _disp_height;