mbed环境下SAMR21开发板3：串口通讯

mbed串口上手也很方便哈。只要包括mbed.h函数即可，一些初始化在mbed.h中已经定义好了。

以下是mbed.h:

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/* mbed Microcontroller Library

 * Copyright (c) 2006-2013 ARM Limited

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef MBED_H

#define MBED_H



#define MBED_LIBRARY_VERSION 113



#include "platform.h"



// Useful C libraries

#include <math.h>

#include <time.h>



// mbed Debug libraries

#include "mbed_error.h"

#include "mbed_interface.h"



// mbed Peripheral components

#include "DigitalIn.h"

#include "DigitalOut.h"

#include "DigitalInOut.h"

#include "BusIn.h"

#include "BusOut.h"

#include "BusInOut.h"

#include "PortIn.h"

#include "PortInOut.h"

#include "PortOut.h"

#include "AnalogIn.h"

#include "Ana**ut.h"

#include "PwmOut.h"

#include "Serial.h"

#include "SPI.h"

#include "SPISlave.h"

#include "I2C.h"

#include "I2CSlave.h"

#include "Ethernet.h"

#include "CAN.h"

#include "RawSerial.h"



// mbed Internal components

#include "Timer.h"

#include "Ticker.h"

#include "Timeout.h"

#include "LowPowerTimeout.h"

#include "LowPowerTicker.h"

#include "LowPowerTimer.h"

#include "LocalFileSystem.h"

#include "InterruptIn.h"

#include "wait_api.h"

#include "sleep_api.h"

#include "rtc_time.h"



using namespace mbed;

using namespace std;



#endif

可见只要你把API打对了，就可以工作了

而Serial.h中又把接收继承父类。

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/* mbed Microcontroller Library

 * Copyright (c) 2006-2013 ARM Limited

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef MBED_SERIAL_H

#define MBED_SERIAL_H



#include "platform.h"



#if DEVICE_SERIAL



#include "Stream.h"

#include "SerialBase.h"

#include "serial_api.h"



namespace mbed {



/** A serial port (UART) for communication with other serial devices

 *

 * Can be used for Full Duplex communication, or Simplex by specifying

 * one pin as NC (Not Connected)

 *

 * Example:

 * @code

 * // Print "Hello World" to the PC

 *

 * #include "mbed.h"

 *

 * Serial pc(USBTX, USBRX);

 *

 * int main() {

 *     pc.printf("Hello World\n");

 * }

 * @endcode

 */

class Serial : public SerialBase, public Stream {



public:

#if DEVICE_SERIAL_ASYNCH

    using SerialBase::read;

    using SerialBase::write;

#endif



    /** Create a Serial port, connected to the specified transmit and receive pins

     *

     *  @param tx Transmit pin

     *  @param rx Receive pin

     *

     *  @note

     *    Either tx or rx may be specified as NC if unused

     */

    Serial(PinName tx, PinName rx, const char *name=NULL);



protected:

    virtual int _getc();

    virtual int _putc(int c);

};



} // namespace mbed



#endif



#endif

而实际操作只要掌握基本函数即可：

类名	方法	用途
Serial	Serial(PinName tx, PinName rx, const char *name=NULL);	构造函数，把tx,rx设成Uart的输出输入管脚
	void baud(int baudrate);	设置Uart的波特率，默认为9600
	void format(int bits=8, Parity parity=SerialBase::None, int stop_bits=1);	设置Uart传输的格式，包括一个字长的位数、奇偶检验的方法、停止位的位数，默认为一个字长为8位，无奇偶检验，1位停止位
	int readable();	返回Uart是否有数据到达
	int writeable();	返回Uart是否还有空间进行数据发送
	void attach(void (*fptr)(void), IrqType type=RxIrq);	设置Uart中断是需要执行的用户自定义函数
	void set_flow_control(Flow type, PinName flow1=NC, PinName flow2=NC);	设置Uart的流控方法，其目标是提高数据发送的可靠性，流控方法有无流控，RTS流控，CTS流控，RTSCTS流控，后面两个常数为流控的管脚设置
	int getc()	从Uart读取一个字符
	int putc(int c);	向Uart发送一个字符
	int printf(const char* format, ...)	格式化Uart的输出，参数等同标准C的printf
	int scanf(const char* format, ...);	格式化Uart的输入，参数等同标准C的scanf

以下是我的程序：

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#include "mbed.h"







 Serial pc(USBTX, USBRX);



 int main() {

     while(1)

     {

     pc.printf("Hello World\n");

     wait(0.2);

     } 

 }

以下是编译通过的截图：



以下是输出结果。总体感觉mbed上手极速地快。

R21的ADC采样波动比较大，可能是什么原因？

shaoziyang 发表于 2016-2-10 21:02
R21的ADC采样波动比较大，可能是什么原因？

可能是外围电路不稳，或ADC采得太快，再有分辨率设低了

您好，请问宏定义中DEVICE_SERIAL和DEVICE_SERIAL_ASYNCH有什么功能上的区别吗？串口本来就是异步的呀？