USART.h File Reference

USART serial communication interface. More...

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Functions
void	initUSART (void)
	Initializes the USART peripheral for serial communication.
void	printString (const char String[])
	Sends a null-terminated string over USART.
uint8_t	receiveByte (void)
	Receives a single byte from USART.
void	transmitByte (uint8_t data)
	Transmits a single byte over USART.

Detailed Description

USART serial communication interface.

This file provides functions for initializing and using the USART (Universal Synchronous/Asynchronous Receiver/Transmitter) peripheral for serial communication. It supports byte transmission/reception, string printing, and formatted output.

Author

Roybel Carbonell Camejo

Date

2026-04-29

Note

All functions are blocking by design for simplicity

See also

CPU.h For F_CPU and BAUD configuration

Definition in file USART.h.

Function Documentation

initUSART()

void initUSART

(

void

)

Initializes the USART peripheral for serial communication.

Configures the USART with the following settings:

• Asynchronous mode
• Baud rate defined by BAUD macro (from CPU.h)
• 8 data bits
• 1 stop bit
• No parity
• Transmitter and receiver enabled

Note

Must be called before any other USART functions

Warning

Baud rate calculation depends on F_CPU macro from CPU.h

See also

CPU.h For F_CPU and BAUD definitions

Initializes the USART peripheral for serial communication.

Configures the USART with baud rate from setbaud.h calculations, enables transmitter and receiver, and sets frame format to 8 data bits, 1 stop bit, no parity.

Note

The setbaud.h header uses F_CPU and BAUD macros from CPU.h

Warning

Baud rate error checking should be performed at compile time

See also

CPU.h For F_CPU and BAUD definitions

<util/setbaud.h> For baud rate calculation macros

Examples

/home/luka/WORK/Programming/ARDUINO/AVR-Square-Wave-Organ/src/main.c.

Definition at line 34 of file USART.c.

Referenced by main().

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printString()

void printString

(

const char

String[]

)

Sends a null-terminated string over USART.

Transmits each character of the string sequentially until the null terminator ('\0') is reached.

Parameters

String

Pointer to the null-terminated string to transmit

Note

Function is blocking - waits for each byte to be transmitted

Warning

String must be properly null-terminated to avoid buffer overrun

See also

transmitByte For single byte transmission

Examples

/home/luka/WORK/Programming/ARDUINO/AVR-Square-Wave-Organ/src/main.c.

Referenced by main().

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receiveByte()

uint8_t receiveByte

(

void

)

Receives a single byte from USART.

Waits for a byte to be received on the USART RX line and returns it. Function blocks until data is available.

Returns

uint8_t The received byte (0-255)

Note

Blocking function - will wait indefinitely for incoming data

Warning

Ensure the transmitter is sending data to avoid infinite wait

Waits for a byte to be received (RXC flag set), then returns the received data from the UDR register.

Returns

uint8_t The received byte (0-255)

Note

Blocking function - waits indefinitely for incoming data

Warning

Ensure data is available before calling to avoid infinite loop

Examples

/home/luka/WORK/Programming/ARDUINO/AVR-Square-Wave-Organ/src/main.c.

Definition at line 88 of file USART.c.

Referenced by main().

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transmitByte()

void transmitByte

(

uint8_t

data

)

Transmits a single byte over USART.

Sends one byte of data through the USART TX line. Function blocks until the transmission is complete.

Parameters

data	The byte (0-255) to transmit

Note

Useful for sending raw binary data

See also

printString For sending strings

printByte For sending bytes as formatted text

Waits for the transmit data register to be empty, then loads the data into the UDR register for transmission.

Parameters

data	The byte to transmit (0-255)

Note

Blocking function - waits until transmission buffer is ready

Warning

If called too frequently, may cause data loss

Examples

/home/luka/WORK/Programming/ARDUINO/AVR-Square-Wave-Organ/src/main.c.

Definition at line 71 of file USART.c.

Referenced by main(), and printString().

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