130 lines
3.8 KiB
C
130 lines
3.8 KiB
C
/*************************************************************************
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Title: Example program for the Interrupt controlled UART library
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Author: Peter Fleury <pfleury@gmx.ch> http://tinyurl.com/peterfleury
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File: $Id: test_uart.c,v 1.7 2015/01/31 17:46:31 peter Exp $
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Software: AVR-GCC 4.x
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Hardware: AVR with built-in UART/USART
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DESCRIPTION:
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This example shows how to use the UART library uart.c
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*************************************************************************/
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#include <stdlib.h>
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <avr/pgmspace.h>
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#include "uart.h"
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/* define CPU frequency in Hz in Makefile */
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#ifndef F_CPU
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#error "F_CPU undefined, please define CPU frequency in Hz in Makefile"
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#endif
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/* Define UART buad rate here */
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#define UART_BAUD_RATE 9600
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int main(void)
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{
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unsigned int c;
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char buffer[7];
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int num=134;
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/*
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* Initialize UART library, pass baudrate and AVR cpu clock
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* with the macro
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* UART_BAUD_SELECT() (normal speed mode )
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* or
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* UART_BAUD_SELECT_DOUBLE_SPEED() ( double speed mode)
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*/
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uart_init( UART_BAUD_SELECT(UART_BAUD_RATE,F_CPU) );
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/*
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* now enable interrupt, since UART library is interrupt controlled
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*/
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sei();
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/*
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* Transmit string to UART
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* The string is buffered by the uart library in a circular buffer
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* and one character at a time is transmitted to the UART using interrupts.
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* uart_puts() blocks if it can not write the whole string to the circular
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* buffer
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*/
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uart_puts("String stored in SRAM\n");
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/*
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* Transmit string from program memory to UART
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*/
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uart_puts_P("String stored in FLASH\n");
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/*
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* Use standard avr-libc functions to convert numbers into string
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* before transmitting via UART
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*/
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itoa( num, buffer, 10); // convert interger into string (decimal format)
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uart_puts(buffer); // and transmit string to UART
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/*
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* Transmit single character to UART
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*/
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uart_putc('\r');
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for(;;)
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{
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/*
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* Get received character from ringbuffer
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* uart_getc() returns in the lower byte the received character and
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* in the higher byte (bitmask) the last receive error
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* UART_NO_DATA is returned when no data is available.
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*
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*/
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c = uart_getc();
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if ( c & UART_NO_DATA )
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{
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/*
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* no data available from UART
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*/
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}
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else
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{
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/*
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* new data available from UART
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* check for Frame or Overrun error
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*/
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if ( c & UART_FRAME_ERROR )
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{
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/* Framing Error detected, i.e no stop bit detected */
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uart_puts_P("UART Frame Error: ");
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}
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if ( c & UART_OVERRUN_ERROR )
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{
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/*
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* Overrun, a character already present in the UART UDR register was
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* not read by the interrupt handler before the next character arrived,
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* one or more received characters have been dropped
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*/
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uart_puts_P("UART Overrun Error: ");
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}
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if ( c & UART_BUFFER_OVERFLOW )
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{
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/*
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* We are not reading the receive buffer fast enough,
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* one or more received character have been dropped
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*/
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uart_puts_P("Buffer overflow error: ");
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}
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/*
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* send received character back
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*/
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uart_putc( (unsigned char)c );
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}
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}
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}
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