• André Bannwart Perina

This project has code snippets from:

• Rinky-dink's UTFT (http://www.rinkydinkelectronics.com/library.php?id=52);
• Sprite_tm's Raspberry micro arcade machine (http://spritesmods.com/?art=rpi_arcade&page=2).

PiDisplayLibs is a simple (and still quite short) collection for simple usage of TFT screens in a Raspberry Pi using GPIO pins. It is based on shared libraries that has the following functions:

• display_init(): Initialise display;
• display_set_xy(): Set coordinate for drawing;
• display_draw(): Draw a pixel;
• display_finish(): Free stuff and finish.

Further details about the functions can be found in the include/display.h file. For usage example, see file src/tests/test1.c.

This project is licensed under GPLv3 (see LICENSE file).

Currently, only Raspberry Pi 3 Model B is supported. It shouldn't be complicated to enable other boards, though:

• PERI_BASE in src/bcmgpio.c must be changed depending on board version:
  • For Raspberry Pi, use 0x20000000;
  • For Raspberry Pi 3, use 0x3F000000 (default).
• Pin numbering may be different on older devices. The macros RS_PIN, RW_PIN, etc. in the drivers source files may be different for boards older than Raspberry Pi 3. Remember to use GPIO numbering according to BCM2835 and not according to pin header position!

Refer to https://www.element14.com/community/servlet/JiveServlet/previewBody/73950-102-9-339300/pi3_gpio.png for pin numbers in Raspberry Pi 3:

• ili9325 320x240 TFT screens:

----------------------------
| RPi3 Pin    | Screen Pin |
| 03 (GPIO02) | RS         |
| 04 (DC 5V)  | 5V         |
| 05 (GPIO03) | RW         |
| 06 (GND)    | GND        |
| 07 (GPIO04) | RD         |
| 11 (GPIO17) | DB10       |
| 13 (GPIO27) | DB11       |
| 15 (GPIO22) | DB12       |
| 19 (GPIO10) | DB13       |
| 21 (GPIO09) | DB14       |
| 23 (GPIO11) | DB15       |
| 29 (GPIO05) | DB17       |
| 31 (GPIO06) | DB19       |
| 33 (GPIO13) | CS         |
| 35 (GPIO19) | RST        |
----------------------------

• bin: Output folder for example binaries;
• include: Includes folder;
  • bcmgpio.h: Header for bcmgpio library;
  • common.h: Header with general purpose macros for assertions and error checking;
  • display.h: Generic header. Developers should include this file;
• lib: Output folder for driver libraries;
• LICENSE: Licence file;
• Makefile: Project makefile;
• obj: Output folder for object files;
• README.md: This file, doh;
• src: Sources folder;
  • bcmgpio.c: Source for the bcmgpio library;
  • ili9325: ili9325 driver folder;
    • ili9325.c: ili9325 driver source;
  • tests: Tests sources;
    • test1.c: Print colour gradients.

Under raspbian, all needed libraries are already provided. To perform a simple compile and use:

• Connect screen to Raspberry Pi board according to the previous section Supported Screens;
• Clone repository;
• Run make for a specific library (e.g. make lib/ili9325.so);
• Run make for one of the example files (e.g. make bin/test1);
• Run example with superuser rights, like sudo (e.g. sudo ./bin/test1 lib/ili9325.so);

PiDisplayLibs comes supplied with some example source codes to give a glimpse of its usage:

• test1.c: Draw some gradient bars. Usage example:

sudo ./bin/test1 DRIVERPATH
	where DRIVERPATH is path to a display driver (*.so)

• test2.c: Scroll a simple text. Usage example:

sudo ./bin/test2 DRIVERPATH FONTPATH STRING REPEATAMT
	where DRIVERPATH is path to a display driver (*.so)
	      FONTPATH is path to a TTF font file (.ttf)
	      STRING is the string to be printed
          REPEATAMT the amount of times the string should be scrolled

• Provide support for older boards automatically;
• Provide support for more TFT displays.