AnalogOut
Use the AnalogOut interface to set the output voltage of an analog output pin specified as a percentage or as an unsigned short. Mbed OS provides separate APIs to use percentage or range. Mbed OS supports a maximum resolution VCC/65,536 V, though the actual resolution depends on the hardware.
Note: Not all pins are capable of being AnalogOut, so check the pinmap for your board.
AnalogOut class reference
| Public Member Functions | |
| AnalogOut (PinName pin) | |
| Create an AnalogOut connected to the specified pin. More... | |
| AnalogOut (const PinMap &&)=delete | |
| Create an AnalogOut connected to the specified pin. More... | |
| void | write (float value) |
| Set the output voltage, specified as a percentage (float) More... | |
| void | write_u16 (unsigned short value) |
| Set the output voltage, represented as an unsigned short in the range [0x0, 0xFFFF]. More... | |
| float | read () |
| Return the current output voltage setting, measured as a percentage (float) More... | |
| AnalogOut & | operator= (float percent) |
| An operator shorthand for write() More... | |
| AnalogOut & | operator= (AnalogOut &rhs) |
| An operator shorthand for write() More... | |
| operator float () | |
| An operator shorthand for read() More... | |
| virtual | ~AnalogOut () |
AnalogOut hello, world
/* 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 example
Create a sine wave.
#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);
}
}
}