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
/*
* Copyright (c) 2017-2020 Arm Limited and affiliates.
* SPDX-License-Identifier: Apache-2.0
*/
#include "mbed.h"
// Initialize a pins to perform analog and digital output functions
// Adjust analog output pin name to your board spec.
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;
ThisThread::sleep_for(1000);
}
}
}
AnalogOut example
Create a sine wave.
/*
* Copyright (c) 2017-2020 Arm Limited and affiliates.
* SPDX-License-Identifier: Apache-2.0
*/
#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
// Adjust analog output pin name to your board spec.
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);
}
}
}