analogWrite Arduino DAC1 output like pwm digitalWrite

Hardware Arduino Due
1

I use analogWrite(DAC1,Output) in my code, but I find it like digital pulse output, rather than expected analog continuous curve, i don't know why, forgive a fresh people in C language.

#include<PID_v1.h>
double Setpoint, Input, Output;
PID myPID(&Input,&Output,&Setpoint,2,5,30,DIRECT);
void setup() 
{
  
  Input= analogRead(A0);
  
  Setpoint = 3000;
  Serial.begin(9600);
  myPID.SetMode(AUTOMATIC);
  myPID.SetSampleTime(10);
  // put your setup code here, to run once:

}

void loop() {
  Input = analogRead(A0);
  Serial.print("Input = ");
  Serial.println(Input);
  myPID.Compute();
  analogWrite(DAC1,Output);
  Serial.print("Output = ");
  Serial.println(Output);
  
  // put your main code here, to run repeatedly:

}
2

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3

I have some Arduino Due borads, so there is DAC1 pin

4

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5

like that

6

Sorry, I have tried it just now, but it's not useful, then the output in oscialloscope are very small. A proportion reduce to 255/4096.

7

I do not have a Due so I cannot comment directly.

The documentation at

in the third paragraph says

The Arduino Due supports analogWrite() on pins 2 through 13, plus pins DAC0 and DAC1. Unlike the PWM pins, DAC0 and DAC1 are Digital to Analog converters, and act as true analog outputs.

8

But in my code, the analogWrite（DAC1, Output）still output signal like PWM, some pulses

9

anyone can help me？

10

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11

Note that the voltage range on the DAC output is 0.55V to 2.75V for 0 to 4095 in code. (1/6 to 5/6 of Vcc)