基于AVR XMEGA-A3BU Xplained控制器的Wifi小车制作(7)---小试牛刀

独活草

      今晚抽空做了下    Atmel XMEGA-A3BU Xplained评估板评测（二）   
https://www.cirmall.com/evaluation/xmega-a3bu-xplained-%e8%af%84%e6%b5%8b%ef%bc%88%e4%ba%8c%ef%bc%89/    里面的例子  
   
      熟悉了下 Atmel Studio 6.0  编程的方式，发现真的跟官方所说是一样子的，  ASF 用于单片机编程很爽。很多底层的驱动软件不用自己去编写，可以直接调用。

Atmel Software Framework框架，进一步简化了开发流程，缩短了开发周期。

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         今晚抽空打开了 Atmel Studio 想看看ASF是如何定义一些操作的，吃了一惊：
首先看让LED灯闪的代码
#include <asf.h>
int main (void)
{
board_init();
sysclk_init();//调用ASF框架函数初始化时钟
delay_init(sysclk_get_cpu_hz());//调用ASF框架函数初始化delay服务
while(1)
{
  delay_ms(500); //调用ASF框架函数延时500Ms
  gpio_set_pin_low(LED0);
  gpio_set_pin_low(LED1);
  delay_ms(500);//调用ASF框架函数延时500Ms
  gpio_set_pin_high(LED0);
  gpio_set_pin_high(LED1);
}
前面的初始化函数  init（）很好理解，然后就是 gpio_set_pin_low(LED0);gpio_set_pin_high(LED0);  这两句让LED0的I/O端口置1、置0 实现闪亮。
很显然，点开asf.h

#ifndef ASF_H
#define ASF_H

#include <ccp.h>
#include <xmega_reset_cause.h>
#include <delay.h>
#include <gpio.h>
#include <board.h>
#include <ioport.h>
#include <interrupt.h>
#include <nvm.h>
#include <parts.h>
#include <sysclk.h>
#include <compiler.h>
#include <status_codes.h>

#endif

又是include 许多的头文件！
打开xmega_reset_cause.h   找到
#define LED0_GPIO                       IOPORT_CREATE_PIN(PORTR, 0)
#define LED1_GPIO                       IOPORT_CREATE_PIN(PORTR, 1)
#define LED0                            LED0_GPIO
#define LED1                            LED1_GPIO
好吧，到这里应该是看懂了，IOPORT_CREATE_PIN(PORTR, 0)  这句函数是定义了 端口PR0,然后这句gpio_set_pin_low(LED0);
是将PR0端口置0
我以前学AVR单片机得知  AVR单片机的I/O口 是要定义它为输入模式还是输出模式的  
好吧，我打开了
                              
                              
                              
                              
然后吃了一惊，ASF 果然是神器    神马预定义的函数都写好了 ，都可以直接拿来调用，节省开发时间。

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    首先是  1 初始化    2设置波特率   3设置数据位数、停止位、校验位    4打开    5发送或者接收数据
    代码：
#include <asf.h>
//&USARTD0发送     &USARTE0接收
#define USART_SERIAL_BAUDRATE               9600
#define USART_SERIAL_CHAR_LENGTH         USART_CHSIZE_8BIT_gc
#define USART_SERIAL_PARITY                     USART_PMODE_DISABLED_gc
#define USART_SERIAL_STOP_BIT                 false
int main (void)
{
board_init();
sysclk_init();//调用ASF框架函数初始化时钟
delay_init(sysclk_get_cpu_hz());//调用ASF框架函数初始化delay服务

//Create USART options struct
static usart_rs232_options_t USART_SERIAL_OPTIONS = {
  .baudrate = USART_SERIAL_BAUDRATE,
  .charlength = USART_SERIAL_CHAR_LENGTH,
  .paritytype = USART_SERIAL_PARITY,
  .stopbits = USART_SERIAL_STOP_BIT
};
sysclk_enable_module(SYSCLK_PORT_D, PR_USART0_bm);//Enable the clock for the USART module
usart_init_rs232(&USARTD0, &USART_SERIAL_OPTIONS);//Initialize in RS232 mode:
sysclk_enable_module(SYSCLK_PORT_E, PR_USART0_bm);//Enable the clock for the USART module
usart_init_rs232(&USARTE0, &USART_SERIAL_OPTIONS);//Initialize in RS232 mode:
uint8_t received_byte;//A variable for the received byte must be added:

while(1)
{   
       usart_putchar(&USARTD0, 'a');//Send an 'a' character via USART
   
        received_byte = usart_getchar(&USARTE0);//Wait for reception of a character:
        usart_putchar(&USARTE0, received_byte);//Echo the character back:
      
        if (    received_byte=='a'   )
          {
             gpio_set_pin_low(LED0);
             delay_ms(2000); //调用ASF框架函数延时500Ms
             gpio_set_pin_high(LED0);
             received_byte=0;     //经过测试  必须加上这一条置0语句，否则会见到LED0一直亮着
             delay_ms(2000);      //经过测试  也要加上这个延迟，否则也看不到效果     预计是因为CPU的指令运算速度太快了，上一句 received_byte=0  没来得及反应 就又有 received_byte=='a'   然后也是LED会一直亮着  
          }

  }

}
传上视频哈


   我用的是串口USARTD0  发生一个字符a,用USARTE0去接收字符，如果接收到字符，就让LED0灯闪亮。
之前打算用  USARTD0 发生 USARTD1  去接收的，可是在
                                         
看到 USARTD0  用的的RXD0 、TXD0 为PD2、PD3  ， USARTD1 用的的RXD1 、TXD1 为PD6、PD7    而 A3BU Xplained板子的J1 J2 J3 J4 木有引出 PD6、PD7     在板子的PCB图上见到这个 PD6、PD7 用于USB转串口去了 。
就随手改了板子引出的资源 USARTE0     对应的是 PE2    PE3
有一点很奇怪  当我打开 ASF 资源中的  usart.c 文件    找到
#ifdef USARTC0
if ((uint16_t)usart == (uint16_t)&USARTC0) {
  sck_pin = IOPORT_CREATE_PIN(PORTC, 1);
}
#endif
#ifdef USARTC1
if ((uint16_t)usart == (uint16_t)&USARTC1) {
  sck_pin = IOPORT_CREATE_PIN(PORTC, 5);
}
#endif
#ifdef USARTD0
if ((uint16_t)usart == (uint16_t)&USARTD0) {
  sck_pin = IOPORT_CREATE_PIN(PORTD, 1);
}
#endif
#ifdef USARTD1
if ((uint16_t)usart == (uint16_t)&USARTD1) {
  sck_pin = IOPORT_CREATE_PIN(PORTD, 5);
}······················

开始以为这些语句的意思是   把PC1作为USARTC0 的输入端    PC5作为 USARTC1的输入端  很显然不对的。与上面芯片的引脚图注解不对应  
看来还得好好研究下usart.c   里面的语句。  

        

              

GY@艳

{:soso_e179:}{:soso_e179:}{:soso_e179:}{:soso_e179:}

xyz504868170

板子怎么来的呀？