UART Driver/Function Library for dual-UART processors (uart2.c)
[Drivers (for AVR peripherals)]

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Detailed Description

 #include "uart2.h" 

Overview

This is a UART driver for AVR-series processors with two hardware UARTs such as the mega161 and mega128. This library provides both buffered and unbuffered transmit and receive functions for the AVR processor UART. Buffered access means that the UART can transmit and receive data in the "background", while your code continues executing.  Also included are functions to initialize the UARTs, set the baud rate, flush the buffers, and check buffer status.

Note:

For full text output functionality, you may wish to use the rprintf functions along with this driver.

About UART operations

Most Atmel AVR-series processors contain one or more hardware UARTs (aka, serial ports). UART serial ports can communicate with other serial ports of the same type, like those used on PCs. In general, UARTs are used to communicate with devices that are RS-232 compatible (RS-232 is a certain kind of serial port).

By far, the most common use for serial communications on AVR processors is for sending information and data to a PC running a terminal program. Here is an exmaple:

    uartInit();                 // initialize UARTs (serial ports)
    uartSetBaudRate(0, 9600);   // set UART0 speed to 9600 baud
    uartSetBaudRate(1, 115200); // set UART1 speed to 115200 baud
   
    rprintfInit(uart0SendByte); // configure rprintf to use UART0 for output
    rprintf("Hello UART0\r\n"); // send "hello world" message via UART0
   
    rprintfInit(uart1SendByte); // configure rprintf to use UART1 for output
    rprintf("Hello UART1\r\n"); // send "hello world" message via UART1

Warning:

The CPU frequency (F_CPU) must be set correctly in global.h for the UART library to calculate correct baud rates. Furthermore, certain CPU frequencies will not produce exact baud rates due to integer frequency division round-off. See your AVR processor's datasheet for full details.

Defines
#define	UART0_DEFAULT_BAUD_RATE   9600
	default baud rate for UART0
#define	UART1_DEFAULT_BAUD_RATE   9600
	default baud rate for UART1
#define	UART0_TX_BUFFER_SIZE   0x0010
	number of bytes for uart0 transmit buffer
#define	UART0_RX_BUFFER_SIZE   0x0080
	number of bytes for uart0 receive buffer
#define	UART1_TX_BUFFER_SIZE   0x0010
	number of bytes for uart1 transmit buffer
#define	UART1_RX_BUFFER_SIZE   0x0080
	number of bytes for uart1 receive buffer
#define	UART_INTERRUPT_HANDLER   SIGNAL
#define	RXCIE   RXCIE0
#define	TXCIE   TXCIE0
#define	UDRIE   UDRIE0
#define	RXEN   RXEN0
#define	TXEN   TXEN0
#define	CHR9   CHR90
#define	RXB8   RXB80
#define	TXB8   TXB80
#define	UBRR0L   UBRR0
#define	UBRR1L   UBRR1
Functions
void	uartInit (void)
void	uart0Init (void)
	Initializes UART0 only.
void	uart1Init (void)
	Initializes UART1 only.
void	uart0InitBuffers (void)
void	uart1InitBuffers (void)
void	uartSetRxHandler (u08 nUart, void(*rx_func)(unsigned char c))
void	uartSetBaudRate (u08 nUart, u32 baudrate)
cBuffer *	uartGetRxBuffer (u08 nUart)
cBuffer *	uartGetTxBuffer (u08 nUart)
void	uartSendByte (u08 nUart, u08 data)
void	uart0SendByte (u08 data)
void	uart1SendByte (u08 data)
int	uart0GetByte (void)
int	uart1GetByte (void)
u08	uartReceiveByte (u08 nUart, u08 *data)
u08	uartReceiveBufferIsEmpty (u08 nUart)
void	uartFlushReceiveBuffer (u08 nUart)
void	uartAddToTxBuffer (u08 nUart, u08 data)
void	uart0AddToTxBuffer (u08 data)
void	uart1AddToTxBuffer (u08 data)
void	uartSendTxBuffer (u08 nUart)
u08	uartSendBuffer (u08 nUart, char *buffer, u16 nBytes)
void	uartTransmitService (u08 nUart)
	interrupt service handlers
void	uartReceiveService (u08 nUart)

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Define Documentation

#define UART0_DEFAULT_BAUD_RATE   9600

Default uart baud rate. This is the default speed after a uartInit() command, and can be changed by using uartSetBaudRate(). Definition at line 71 of file uart2.h.

#define UART_INTERRUPT_HANDLER   SIGNAL

Type of interrupt handler to use for uart interrupts. Value may be SIGNAL or INTERRUPT. Warning: Do not change unless you know what you're doing. Definition at line 105 of file uart2.h.

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Function Documentation

void uart0AddToTxBuffer (  u08  data  )

AddToTxBuffer commands with the UART number hardcoded Use this with printfInit() - example: printfInit(uart0AddToTxBuffer); Definition at line 248 of file uart2.c.

int uart0GetByte (  void   )

Gets a single byte from the uart receive buffer. Returns the byte, or -1 if no byte is available (getchar-style). Definition at line 191 of file uart2.c.

void uart0InitBuffers (  void   )

Initializes transmit and receive buffers. Automatically called from uartInit() Definition at line 92 of file uart2.c.

void uart0SendByte (  u08  data  )

SendByte commands with the UART number hardcoded Use these with printfInit() - example: printfInit(uart0SendByte); Definition at line 179 of file uart2.c.

void uartAddToTxBuffer (  u08  nUart, u08  data )

Add byte to end of uart Tx buffer. Definition at line 242 of file uart2.c.

void uartFlushReceiveBuffer (  u08  nUart  )

Flushes (deletes) all data from receive buffer. Definition at line 231 of file uart2.c.

cBuffer* uartGetRxBuffer (  u08  nUart  )

Returns pointer to the receive buffer structure. Definition at line 148 of file uart2.c.

cBuffer* uartGetTxBuffer (  u08  nUart  )

Returns pointer to the transmit buffer structure. Definition at line 154 of file uart2.c.

void uartInit (  void   )

Initializes uart. Note: After running this init function, the processor I/O pins that used for uart communications (RXD, TXD) are no long available for general purpose I/O. Definition at line 44 of file uart.c.

u08 uartReceiveBufferIsEmpty (  u08  nUart  )

Returns TRUE/FALSE if receive buffer is empty/not-empty. Definition at line 237 of file uart2.c.

u08 uartReceiveByte (  u08  nUart, u08 *  data )

Gets a single byte from the uart receive buffer. Function returns TRUE if data was available, FALSE if not. Actual data is returned in variable pointed to by "data". Example usage: char myReceivedByte; uartReceiveByte(0, &myReceivedByte ); Definition at line 212 of file uart2.c.

u08 uartSendBuffer (  u08  nUart, char *  buffer, u16  nBytes )

sends a buffer of length nBytes via the uart using interrupt control. Definition at line 266 of file uart2.c.

void uartSendByte (  u08  nUart, u08  data )

Sends a single byte over the uart. Definition at line 160 of file uart2.c.

void uartSendTxBuffer (  u08  nUart  )

Begins transmission of the transmit buffer under interrupt control. Definition at line 258 of file uart2.c.

void uartSetBaudRate (  u08  nUart, u32  baudrate )

Sets the uart baud rate. Argument should be in bits-per-second, like uartSetBaudRate(9600); Definition at line 128 of file uart2.c.

void uartSetRxHandler (  u08  nUart, void(*)(unsigned char c)  rx_func )

Redirects received data to a user function. Definition at line 118 of file uart2.c.

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