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这是MCF52259开发板上写的一个演示485通信的例子。实现的功能很简单，就是通过485收到一个字节就立马再通过485发出去
/*********************************************************
@ Nicrosystem Freescale coldfire MCF52259 Development Board
@ NSCF52259-R1
@ author:bluehacker
@ date:2009-12-01
**********************************************************/
#include "uart.h"
uint8 uart_init(uint8 channel,uint32 sysClockKhz,uint32 baudRate)
{
uint16 ubgs;
if(channel>2)
{
return 1;//error
}
set_gpio_uart(channel);
/*
* Reset Transmitter
*/
MCF_UART_UCR(channel) = MCF_UART_UCR_RESET_TX;
/*
* Reset Receiver
*/
MCF_UART_UCR(channel) = MCF_UART_UCR_RESET_RX;
/*
* Reset Mode Register
*/
MCF_UART_UCR(channel) = MCF_UART_UCR_RESET_MR;
/*
* No parity, 8-bits per character
*/
MCF_UART_UMR(channel) = (0
| MCF_UART_UMR_PM_NONE
| MCF_UART_UMR_BC_8 );
/*
* No echo or loopback, 1 stop bit
*/
MCF_UART_UMR(channel) = (0
| MCF_UART_UMR_CM_NORMAL
| MCF_UART_UMR_SB_STOP_BITS_1);
/*
* Set Rx and Tx baud by SYSTEM CLOCK
*/
MCF_UART_UCSR(channel) = (0
| MCF_UART_UCSR_RCS_SYS_CLK
| MCF_UART_UCSR_TCS_SYS_CLK);
/*
* Mask all UART interrupts
*/
MCF_UART_UIMR(channel) = 0;
/*
* Calculate baud settings
*/
ubgs = (uint16)((sysClockKhz * 1000)/(baudRate * 32));
MCF_UART_UBG1(channel) = (uint8)((ubgs & 0xFF00) >> 8);
MCF_UART_UBG2(channel) = (uint8)(ubgs & 0x00FF);
/*
* Enable receiver and transmitter
*/
MCF_UART_UCR(channel) = (0
| MCF_UART_UCR_TX_ENABLED
| MCF_UART_UCR_RX_ENABLED);
return 0;//success
}
void set_gpio_uart(uint8 channel)
{
switch(channel)
{
case 0:
MCF_GPIO_PUAPAR|=MCF_GPIO_PUAPAR_UTXD0_UTXD0 |
MCF_GPIO_PUAPAR_URXD0_URXD0 |MCF_GPIO_PUAPAR_URTS0_URTS0 |
MCF_GPIO_PUAPAR_UCTS0_UCTS0 ;
break;
case 1:
MCF_GPIO_PUBPAR|=MCF_GPIO_PUBPAR_UTXD1_UTXD1 |
MCF_GPIO_PUBPAR_URXD1_URXD1 ;
break;
case 2:
MCF_GPIO_PUCPAR|=MCF_GPIO_PUCPAR_UTXD2_UTXD2 |
MCF_GPIO_PUCPAR_URXD2_URXD2 ;
break;
default:
break;
}
}
/*
* Wait for a character to be received on the specified UART
*
* Return Values:
* the received character
*/
char uart_getchar (uint8 channel)
{
/* Wait until character has been received */
while (!(MCF_UART_USR(channel) & MCF_UART_USR_RXRDY))
{
};
return (char)MCF_UART_URB(channel);
}
/********************************************************************/
/*
* Wait for space in the UART Tx FIFO and then send a character
*/
void uart_putchar (uint8 channel, char ch)
{
/* Wait until space is available in the FIFO */
while (!(MCF_UART_USR(channel) & MCF_UART_USR_TXRDY))
{
};
/* Send the character */
MCF_UART_UTB(channel) = (uint8)ch;
}
/*********************
* send a string using poll mode
*******************/
void uart_putstr(uint8 channel, char *str)
{
while(*str!=0)
{
uart_putchar(channel,*str++);
}
}
//main.c
/*********************************************************
@ Nicrosystem Freescale coldfire MCF52259 Development Board
@ NSCF52259-R1
@ author:bluehacker
@ date:2009-12-01
**********************************************************/
/*
* main implementation: use this sample to create your own application
*
*/
#include "support_common.h" /* include peripheral declarations and more */
#if (CONSOLE_IO_SUPPORT || ENABLE_UART_SUPPORT)
/* Standard IO is only possible if Console or UART support is enabled. */
#include
#endif
#include "uart.h"
#include "delay.h"
void rs485_init(uint32 baudRate)
{
MCF_GPIO_PUCPAR &=0x3f;
MCF_GPIO_DDRUC|=MCF_GPIO_DDRUC_DDRUC3 ;
MCF_GPIO_PORTUC&=~MCF_GPIO_PORTUC_PORTUC3 ;
uart_init(1,80000,baudRate);
}
char rs485_getchar()
{
MCF_GPIO_PORTUC&=~MCF_GPIO_PORTUC_PORTUC3 ;
return uart_getchar(1);
}
void rs485_putchar(char ch)
{
MCF_GPIO_PORTUC|=MCF_GPIO_PORTUC_PORTUC3 ;
uart_putchar(1,ch);
while (!(MCF_UART_USR(1) & MCF_UART_USR_TXEMP))
{
};
MCF_GPIO_PORTUC&=~MCF_GPIO_PORTUC_PORTUC3 ;
}
int main(void)
{
int counter = 0;
char c=0;
#if (CONSOLE_IO_SUPPORT || ENABLE_UART_SUPPORT)
printf("Hello World in C from MCF52259 derivative on MCF52259 board\n\r");
fflush(stdout);
#endif
pit_init(0);
rs485_init(9600);
for(;;) {
counter++;
//rs485_putchar(c);
c=rs485_getchar();
delay_ms(80000,0,10);
rs485_putchar(c);
}
}
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阿莫论坛20周年了！感谢大家的支持与爱护！！
一只鸟敢站在脆弱的枝条上歇脚，它依仗的不是枝条不会断，而是自己有翅膀，会飞。
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发表于 2014-12-30 13:01:53
