XMEGA tutorial: LCD display (05)
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Blinking diodes mentioned in the previous part of our tutorial is cool, however not very communicative. That's why before moving on to discussing particular peripherals of XMEGA microcontrollers, we will learn how to operate 16x2 LCD text display with HD44780 driver.
This paragraph’s aim is to acquaint the reader with basic knowledge on how to control the display, although we are not going to create it’s function library from scratch. Instead, we will use a template provided by Radosław Kwiecień and available on his website radzio.dxp.pl. I have adjusted his function library to work with XMEGA microcontrollers, so that we can use the display in following parts of the preparation course. We will see how new libraries can be added to the Atmel Studio project by the way.
This paragraph’s aim is to acquaint the reader with basic knowledge on how to control the display, although we are not going to create it’s function library from scratch. Instead, we will use a template provided by Radosław Kwiecień and available on his website radzio.dxp.pl. I have adjusted his function library to work with XMEGA microcontrollers, so that we can use the display in following parts of the preparation course. We will see how new libraries can be added to the Atmel Studio project by the way.
XMEGA tutorial: ports (04)
Port is the fundamental peripheral, which enables connection between microcontroller and other devices. In well known and appreciated processors: ATtiny & ATmega each port used to have three registers: PIN, PORT and DDR. However in XMEGA microcontrollers there are 21 registers for each port... but don't worry! Using the XMEGA ports is even easier than in ATmega!
All ports have unique name: PORTA, PORTB, PORTC... and so on until the end of alphabet! Within each port there are several registers and some of the most important are listed below:
All ports have unique name: PORTA, PORTB, PORTC... and so on until the end of alphabet! Within each port there are several registers and some of the most important are listed below:
- DIR – this one register decides which of the pins is supposed to be an input or output. Typing 1 will configure the pin as an output and 0 as input. For example, the instruction below sets pins 3 and 6 as outputs, therefore the other pins will be inputs:
PORTA.DIR = PIN3_bm | PIN6_bm;
- OUT - this is the output register. Typing 1 will cause the appearance of high state of appropriate "leg" of port, while 0 means low state.
- IN – is the input register, used for reading current pin state. Here is the example of conditional statement (branch control structure) which checks if the state on the pin E5 is high:
if(PORTE.IN & PIN5_bm)
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