Fede.tft at 22:11, 27 April 2014

2014-04-27T22:11:28Z

← Older revision		Revision as of 22:11, 27 April 2014
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	* ''go(int x, int y)'' moves the cursor to the specified position		* ''go(int x, int y)'' moves the cursor to the specified position
	* ''printf()'' prints to the display, using the standard C formatting rules.		* ''printf()'' prints to the display, using the standard C formatting rules.

			== Thread safety considerations ==

			The ''Lcd44780'' is not thread-safe. Concurrent access from multiple threads requires the use of a mutex to protect it against concurrent accesses.

	== Examples ==		== Examples ==

Fede.tft at 11:08, 25 April 2014

2014-04-25T11:08:28Z

← Older revision		Revision as of 11:08, 25 April 2014
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	[[File:Vfd44780.jpg]]		[[File:Vfd44780.jpg]]

			== Related pages ==
			* [[Example: HD44780\|HD44780 Example]]

	[[Category:API]]		[[Category:API]]

Fede.tft: Created page with "Include statements and namespace required to use this library #include using namespace miosix; This is a C++ library, it cannot..."

2014-04-25T11:04:42Z

Created page with "Include statements and namespace required to use this library <source lang="CPP"> #include <util/lcd44780.h> using namespace miosix; </source> This is a C++ library, it cannot..."

New page

Include statements and namespace required to use this library
<source lang="CPP">
#include <util/lcd44780.h>
using namespace miosix;
</source>
This is a C++ library, it cannot be used from a C source file.

The [https://en.wikipedia.org/wiki/HD44780_Character_LCD HD44780] is a standard controller for alphanumeric LCD displays. Miosix supports these displays through the ''Lcd44780'' class.

== Hardware connections ==

The connection to the display requires 6 GPIOs connected to the display. Here are the LCD pinout connections
* Pin 1: GND, connect to ground
* Pin 2: VCC, connect to a 5V power supply. Some displays may also work with 3.3V
* Pin 3: Contrast adjustment, connect the center tap of a potentiometer with the other two ends connected to VCC and GND
* Pin 4: RS, connect to a GPIO
* Pin 5: RW. the Miosix driver requires to connect this pin to ground
* Pin 6: E, connecto to a GPIO
* Pin 7: D0, leave unconnected or connect to VCC
* Pin 8: D1, leave unconnected or connect to VCC
* Pin 9: D2, leave unconnected or connect to VCC
* Pin 10: D3, leave unconnected or connect to VCC
* Pin 11: D4, connect to a GPIO
* Pin 12: D5, connect to a GPIO
* Pin 13: D6, connect to a GPIO
* Pin 14: D7, connect to a GPIO

Additionally, some display may have two more pins to power a backlight, as LCDs cannot be seen in the dark.

== Software interfacing ==

To use the LCD with Miosix, you first have to connect the 6 pins of the LCD to GPIOs on your board. Any GPIO can be used, so long as it is a free GPIO not used for something else. Then you have to declare the GPIOs in your program as explained in the [[GPIO tutorial]].

<source lang="CPP">
typedef Gpio<GPIOB_BASE,12> d4;
typedef Gpio<GPIOB_BASE,13> d5;
typedef Gpio<GPIOB_BASE,14> d6;
typedef Gpio<GPIOB_BASE,15> d7;
typedef Gpio<GPIOC_BASE,1> rs;
typedef Gpio<GPIOC_BASE,2> e;
</source>

You can then declare an instance of the ''Lcd44780'' class, whose constructor takes 8 parameters: the 6 GPIOs (in te following order: RS, E, D4, D5, D6, D7), and the number of rows and columns of the display. The most common display type is 2 lines by 16 columns.

<source lang="CPP">
Lcd44780 display(rs::getPin(),e::getPin(),d4::getPin(),d5::getPin(),d6::getPin(),d7::getPin(),2,16);
</source>

The ''getPin()'' member function of the GPIO class returns an object that allows to pass GPIOs as arguments to a function.

Once you have an instance of the ''Lcd44780'', which in the example above is called ''display'', you can call the following member functions on it:
* ''clear()'' clears the display
* ''go(int x, int y)'' moves the cursor to the specified position
* ''printf()'' prints to the display, using the standard C formatting rules.

== Examples ==

An example program for driving an HD44780-compatible display can be found in the ''mioisx/_examples/hd44780'' directory.

[[File:Lcd44780.jpg]]

Note that you are not restricted to LCD display, there are other display technologies that are HD44780-compatible, for example some [https://en.wikipedia.org/wiki/Vacuum_fluorescent_display VFD] displays like this work as well

[[File:Vfd44780.jpg]]

[[Category:API]]

HD44780 LCD tutorial - Revision history

Fede.tft at 22:11, 27 April 2014

Fede.tft at 11:08, 25 April 2014

Fede.tft: Created page with "Include statements and namespace required to use this library #include using namespace miosix; This is a C++ library, it cannot..."