AVRLIB

Hardware Abstraction Library for AVR Microcontrollers.

AVRLIB is a high level Hardware Abstarction API library for interfacing LCDs, GPIO, USART etc. to the AVR series of Microcontrollers.

Table of Contents

Features

How to Program

Makefile

How to use the API in your project

LCD API

GPIO API

UART API

I2C API

License

Features of this library:

• Written in C, well documented and includes many examples.
• Includes APIs for most peripherals like LCD, RTC, GPIO, UART, I2C etc.
• Most of the funtions required by a peripheral have predefined APIs functions.
• Supports the complete family of AVR Microcontrollers.

Every API Provides a set of funtions to interface the peripheral. Every funtions is documented in the respective API's header file file. Every API has a API_example.c file which shows the usage of the funtions.

Programming the Microcontroller

This library comes with a Makefile which includes configurations and targets for programming the controller using AVRDUDE. The microcontroller can be programmed via any other method if required.

Makefile

The Makefile has to be configured for using it properly. all APIs that you wish to use need to be added to the makefile variable OBJ=$(LIB)"API NAME" without quotes. example:

#Define the AVR Microcontroller here                                                             
MCU=atmega32                                                                                            
#Define the name of your C file here                                                             
TARGET=example
#add all the APIs you need using $(LIB)api1 $(LIB)api2 ... format.
OBJ=$(TARGET).o $(LIB)lcd.o

Using an API in your project

1. define the microcontroller you are using in the Makefile using the MCU variable.

#Define the AVR Microcontroller here                                                             
MCU=atmega32

2. include the API in your project by adding #include "API.h" to the top of your source file.

#include "gpio.h"

3. Read the API.h file for configuration and function documentation and use the funtions in your project.

4. Add all names of all the APIs that you have used in your project in the Makefile in the OBJ variable using the following syntax

#add all the APIs you need using $(LIB)api1 $(LIB)api2 ... format.
#Don't remove the $(TARGET).o , just add all the required apis after $(TARGET).o. Examole for using LCD and GPIO api
OBJ=$(TARGET).o $(LIB)lcd.o  $(LIB)gpio.o

5. Edit the config.h file present in src/include/ and add details about the cpu frequency and target microcontroller

#define __MCU__ATMEGA32__
#define F_CPU 16000000UL

LCD API

This API provides functions to interface HD44780 LCD in both 4 and 8 bit mode. This only supports 16x2 and 20x4 LCDs, but support for other LCDs can be added easily.

Configuring the API

Edit the lcd_config.h header file which can be found at src/include/, in this file define the pins which you have used to connect you LCD to your microcontroller. Change the file according to your connections, variables which need changes are given below.

/*LCD TYPES
 * define the lcd type with the options given below
 * 1 - 16 X 2
 * 2 - 20 X 4 */
#define LCDTYPE		1

/*PIN CONFIGURATIONS
 *define the pins conncted to the lcd
 *DATAPORT is the port connected to data pins
 *similarly define all connections*/
#define DATAPORT	PORTC
#define DATAPIN		PINC
#define DATADDR		DDRC
#define RS		PD3
#define RW		PD4
#define EN		PD7
#define CONPORT		PORTD
#define CONPIN		PIND
#define CONDDR		DDRD

Functions Provided by LCD API

1. lcd_init()

This functions initilizes the LCD and sets up all the registers. It has to be called before using any other lcd api function. It takes mode as the parameter and doesn't return anything. mode = 0 --> 8 bit mode. mode = 1 --. 4 bit mode.

Parameters - unsigned int mode

Returns - Void

2. lcd_send_command(unsigned char command)

This function can be called to send a command to the lcd in 8 bit format, for example 0x01 (clear screen).

Parameters - unsigned char command

Returns - Void

Example:

unsigned char cmd = 0x01;
lcd_send_command(cmd);

3. lcd_send_data(unsigned char data)

This function can be called to send data(single character) to the lcd in, for example 'P'.

Parameters - unsigned char data

Returns - Void

Example:

unsigned char data = 'P';
lcd_send_command(data);

4. lcd_write_string(char * string)

This function can be called to send a string to the lcd, for example "HELLO LCD". It takes a character pointer to a string and return nothing.

Parameters - char * command

Returns - Void

Example:

char *string = "HELLO LCD :D";
lcd_send_command(string);

5. lcd_set_cursor(int row, int column)

This function can be called to change the position of the cursor to any row and column of the LCD, for example 2,0 (second row, first column). It takes two integers as parameters for row and column, it assumes 0,0 as first row and first column.

Parameters - int row, int column

Returns - Void

Example:

int row = 2;
int col = 1;
lcd_set_cursor(row,col);

6. lcd_clrscr()

This function can be called to clear the screen and bring the cursor to home position (0,0).

Parameters - void

Returns - Void

Example:

lcd_clrscr();

7. lcd_clrscr()

This function can be called to clear the screen and bring the cursor to home position (0,0).

Parameters - void

Returns - Void

Example:

lcd_clrscr();

8. lcd_show_cursor_underline()

This function can be called to make the cursor appear as an underscore i.e. '_'.

Parameters - void

Returns - Void

Example:

lcd_show_cursor_underline();

9. lcd_show_cursor_block()

This function can be called to make the cursor appear as a block or a box.

Parameters - void

Returns - Void

Example:

lcd_show_cursor_block();

10. lcd_hide_cursor()

This function can be called to hide the cursor, any of the above two functions can be called to get back the cursor.

Parameters - void

Returns - Void

Example:

lcd_hide_cursor();

GPIO API

This API provides functions to interface GPIOs. It provides functions for easy usage of gpios, the functions are similar to arduino's pinMode and digitalWrite functions.

Configuring the API

Edit the config.h header file which can be found at src/include/, in this file define the crystal frequency and the mcu name. This API doesn't requires any other configurations

Functions Provided by GPIO API

1. gpio_set_mode_output(char port, unsigned int gpio)

This function initializes the given gpio of the given port as an output. It takes Port name and pin as parameters, doesn't return anything.

Parameters - char port, unsigned int gpio

Returns - Void

Example:

gpio_set_mode_output('B',5); // Initializing pin 5 of port B as an output

2. gpio_set_mode_input(char port, unsigned int gpio, unsigned int pull);

This function sets the gpio of given port as an input. It takes Port name, pin, and pull(0 or 1) as parameters, doesn't return anything.

Parameters - char port, unsigned int gpio, unsigned int pull

Returns - Void

Example:

gpio_set_mode_input('B',5,1); // Initializing pin 5 of port B as an input with internal pull-up
gpio_set_mode_input('B',0,0); // Initializing pin 0 of port B as an input with internal pull-down

3. gpio_set_low(char port, unsigned int gpio);

This function writes a 0 to the given pin of the given port.

Parameters - char port, unsigned int gpio

Returns - Void

Example:

gpio_set_low('B',3); //Writing a 0 to pin 3 of Port B

4. gpio_set_high(char port, unsigned int gpio);

This function writes a 1 to the given pin of the given port.

Parameters - char port, unsigned int gpio

Returns - Void

Example:

gpio_set_high('A',3); //Writing a 1 to pin 3 of Port B

5. unsigned int gpio_read_pin(char port, unsigned int gpio);

This function reads the pin of given port and returns the value as an int(0 or 1)

Parameters - char port, unsigned int gpio

Returns - unsigned int value

Example:

unsigned int value;
value = gpio_read_pin("C", 3); //reading the value of pin 3 of Port C and stroing it in value.

UART API

This API provides functions to interface the UART peripheral of the microcontroller.

Configuring the API

Edit the uart_config.h header file which can be found at src/include/, in this file define the baud rate for the uart communication. This API doesn't requires any other configurations

Functions Provided by UART API

1. uart_init(void)

This Functions initializes the uart register with the given baud rate and data frame specification, they can exclusively be edited in src/lib/uart.c This function has to be called before using any other API functions

Parameters - Void

Returns - Void

Example:

uart_init(); // Initializing uart with baud rate given in uart_config.h

2. char uart_receive(void);

This function reads the uart buffer and returns the data as an unsigned character.

Parameters - Void

Returns - char

Example:

char data;
data = uart_receive();

3. uart_send(char data);

This function can be called to send data through UART as an unsigned character(one byte).

Parameters - char data

Returns - Void

Example:

uart_send('P');

4. uart_send_string(char* StringPtr);

This function can be called to send a string through the UART by providing the pointer to the string as the parameter.

Parameters - char* ptr

Returns - Void

Example:

char string[] = "Hello";
uart_send_string(string);

5. uart_receive_string(char* StringPtr, unsigned int len);

This function can be called to receive a string through the UART by providing the pointer to the place where the string has to be stored and also the length of the string.

Parameters - char* ptr

Returns - Void

Example:

unsigned int len = 5;
char string[5];
uart_receive_string(string, len);

I2C API

This API provides functions to interface the I2C peripheral of the microcontroller in master mode.

Configuring the API

Edit the i2c_config.h header file which can be found at src/include/, in this file define the scl frequency for the i2c communication. This API doesn't requires any other configurations

Functions Provided by I2C API

1. i2c_init(void)

This Functions initializes the i2c TWBR register with the given frequency and specifications, they can exclusively be edited in src/lib/i2c.c This function has to be called before using any other API functions

Parameters - Void

Returns - Void

Example:

i2c_init(); // Initializing i2c with frequency given in i2c_config.h

2. unsigned int i2c_start(unsigned int address);

This function creates the start condition on the i2c bus and intitializes the communication with the device with given address, which is in the form 7bit address + R/W.

Parameters - unsigned int address It is the slave address of the slave device. Returns - unsigned int error It returns the status for the api call:- 3 :- Start condition couldn't be created on the bus. 0 :- Successfully created start, SLA+W/R condition and ACK recieved. 1 :- Successfully created start, SLA+W/L condition and NACK recieved. 2 :- Successfully created start condition, but error in SLA+R/W.

Example:

unsigned int error;
error = i2c_start();
if (!error){
/*user code*/
}

3. unsigned int i2c_repeated_start(unsigned int address);

This function creates the repeated start condition on the i2c bus and intitializes the communication with the device with given address, which is in the form 7bit address + R/W.

Parameters - unsigned int address It is the slave address of the slave device. Returns - unsigned int error It returns the status for the api call:- 3 :- Repeated Start condition couldn't be created on the bus. 0 :- Successfully created repeated start, SLA+W/R condition and ACK recieved. 1 :- Successfully created repeated start, SLA+W/L condition and NACK recieved. 2 :- Successfully created repeated start condition, but error in SLA+R/W.

Example:

unsigned int error;
error = i2c_repeated_start();
if (!error){
/*user code*/
}

4. unsigned int i2c_write(char data);

This function sends the 8 bit data on the bus.

Parameters - char data It is data to be transmitted on the bus. Returns - unsigned int error It returns the status for the api call:- 0 :- Successfully sent the data and ACK recieved. 1 :- Successfully sent the data and NACK recieved. 2 :- An error occured in transmission.

Example:

unsigned int error;
char data = 0xff;
error = i2c_send(data);
switch (error){
/*user code*/
}

5. char data i2c_read(unsigned int send_nack);

This function sends the 8 bit data on the bus.

Parameters - unsigned int send_nack If it is equal to 0 then ACK is sent after receiving the data, else NACK is sent. Returns - char data It returns the data read from the bus. Example:

char data;
data = i2c_read(0); //for ACK after receiving
data = i2c_read(1); //for NACK after receiving

6. Void i2c_stop(void);

This stops the i2c communication.

Parameters - void Returns - void Example:

i2c_stop();

LICENCE

GNU General Public License Version 3