#WARNING:

• If you make optimization (OPTIMIZE == 1) of this code, it will uses ~500bytes, but you will not be able to write baud rate(9600, 115200, ETC) value in 'usart_init();' because in this case baud rate to UBRRn converter is disabled, so you would write directly UBRRn(103, 8, ETC) value(check in ATmega328p datasheet).

Baud rate -> UBRRn (UX2n == 0): 9600 -> 103 38400 -> 25 115200 -> 8

• Of this library target is small memory usage and fast execution.

• In code are preprocesors where user is able active or deactive some modes:

1. Active or deactive ISR by change value of ISR_EN (Default value is 1 as activated);

2. user can change memory usage by changeing value of OPTIMIZE (Default value is 0 as disabled);

#Functions:

• void usart_init(uint32_t baud, uint8_t speed);
• void usart_sendChar(char acter);
• void usart_sendStr(char *str);
• char usart_getChar(void);
• uint8_t usart_getStr(void);
• void usart_clear(void);

#libraries

• #include <avr/io.h>
• #include <avr/interrupt.h>

#variables

• volatile static char RECEIVED_CHAR = '\0';
• volatile static char RECEIVED_BUFFER[_BUFFER_SIZE] = {0};
• volatile static uint16_t RX_COUNT0 = 0;
• volatile static uint8_t TX_READY = 1;

#ISR

• USART_RX_vect
• USART_TX_vect

#Configurations

• #define OPTIMIZE 0

• #define ISR_EN 1

#Hardware requirements

• ATmega328p

#Software requirements

• AVR-GCC
• AVR-OBJCOPY
• AVRDUDE
• AVR-SIZE
• MAKE

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#About developer

• youtube: https://www.youtube.com/channel/UCRLxLcBO9MSjiLtP3xOF5yw

• github: https://github.com/developer328

• twitter: https://twitter.com/nikoloz328