Analog Out

DAC

A digital-to-analog converter (DAC) turns a numeric sample into a voltage between 0 V and the chip's reference voltage (3.3 V on Endpoint, 12-bit resolution). The output is a weak signal and is not meant to drive a load directly. Add an op-amp or similar buffer to drive something like a speaker.

WriteValue accepts either a raw 12-bit integer (0 to 4095) or a double in the range 0.0 to 1.0.

.NET

using GHIElectronics.Endpoint.Core;
using GHIElectronics.Endpoint.Devices.Dac;

var dac = DacController.FromName(EPDomino24.Dac.Id);
using var output = dac.OpenChannel(EPDomino24.Dac.PA5);

double level = 0, step = 0.1;
int direction = 1;

while (true) {
    output.WriteValue(level);
    if (level >= 0.9) direction = -1;
    if (level <= 0.1) direction = 1;
    level += step * direction;
    Thread.Sleep(1000);
}

Python

import time
from GHIElectronics.Endpoint.Core import EPDomino24
from GHIElectronics.Endpoint.Devices.Dac import DacController

dac = DacController.FromName(EPDomino24.Dac.Id)
with dac.OpenChannel(EPDomino24.Dac.PA5) as output:
    level = 0.0
    step = 0.1
    direction = 1

    while True:
        output.WriteValue(level)
        if level >= 0.9: direction = -1
        if level <= 0.1: direction = 1
        level += step * direction
        time.sleep(1)

C/C++

#include <chrono>
#include <thread>
#include <endpoint/Dac.h>
#include <endpoint/EPDomino24.h>

using namespace GHIElectronics::Endpoint::Core;
using namespace GHIElectronics::Endpoint::Devices::Dac;

auto dac = DacController::FromName(EPDomino24::Dac::Id);
auto output = dac.OpenChannel(EPDomino24::Dac::PA5);

double level = 0.0, step = 0.1;
int direction = 1;

while (true) {
    output.WriteValue(level);
    if (level >= 0.9) direction = -1;
    if (level <= 0.1) direction = 1;
    level += step * direction;
    std::this_thread::sleep_for(std::chrono::milliseconds(1000));
}

tip

Do not use analog outputs to control the power of an LED or a motor. Use PWM for that.

PWM

PWM can also simulate an analog voltage when filtered or driving a duty-cycle-responsive load (motor, LED). See PWM for details.