Mbed OS 文档翻译 之 参考（API（驱动（AnalogOut）））

AnalogOut

使用 AnalogOut 接口将模拟输出引脚的输出电压设置为百分比或无符号短路。Mbed OS 提供单独的 API 以使用百分比或范围。  Mbed OS 支持最大分辨率 VCC/65536 V，但实际分辨率取决于硬件。

        注意: 并非所有引脚都能够成为 AnalogOut，因此请检查电路板的 pinmap。

AnalogOut 类参考

mbed::AnalogOut 类参考

公共成员函数
	AnalogOut (PinName pin)
void	write (float value)
void	write_u16 (unsigned short value)
float	read ()
AnalogOut &	operator= (float percent)
AnalogOut &	operator= (AnalogOut &rhs)
	operator float ()

受保护的成员函数
virtual void	lock ()
virtual void	unlock ()

受保护的属性
dac_t	_dac
PlatformMutex	_mutex

AnalogOut hello, world

main.cpp                                                                                                                                             导入到 Mbed IDE

/* mbed Example Program
 * Copyright (c) 2006-2015 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.
 */

#include "mbed.h"

// Initialize a pins to perform analog and digital output fucntions
AnalogOut  aout(A5);
DigitalOut dout(LED1);

int main(void)
{
    while (1) {
        // change the voltage on the digital output pin by 0.1 * VCC
        //  and print what the measured voltage should be (assuming VCC = 3.3v)
        for (float i = 0.0f; i < 1.0f; i += 0.1f) {
            aout = i;
            printf("aout = %1.2f volts\n", aout.read() * 3.3f);
            // turn on the led if the voltage is greater than 0.5f * VCC
            dout = (aout > 0.5f) ? 1 : 0;
            wait(1.0f);
        }
    }
}

AnalogOut 示例

创建一个正弦波。

main.cpp                                                                                                                                               导入到 Mbed IDE

#include "mbed.h"

const double pi = 3.141592653589793238462;
const double amplitude = 0.5f;
const double offset = 65535/2;

// The sinewave is created on this pin
AnalogOut aout(A5);

int main()
{
    double rads = 0.0;
    uint16_t sample = 0;
    
    while(1) {
        // sinewave output
        for (int i = 0; i < 360; i++) {
            rads = (pi * i) / 180.0f;
            sample = (uint16_t)(amplitude * (offset * (cos(rads + pi))) + offset);
            aout.write_u16(sample);
        }
    }
}