GP82XX - Issue writing DAC values - random sine-waves intermitently appearing

I purchased and received two GP8211 DAC for a project I am working on. I needed the option of larger range (0-10V) and also the additional resolution (15-bit).

Set-up.

I followed the online Wiki. Downloaded and installed the library from github. Connected an Arduino Uno (official) and upload the demo code from the Examples. This worked.

Problem.

Next, I modified the example to cycle through various values.

I noted that at certain times, a clean output was being generated. However, at other times, a large amplitude, high-frequency sine-wave was being generated.

I tried both the the GP8211 I purchased and had the same issue. Thinking it might be my Arduino, I uploaded my script to an Elegoo Mega 2560; unfortunately I ran into the same problem.

Below is the sketch I am running and also a screencast of the issue happening as I cycle up and down through difference values.

Any help with this issue would be greatly appreciated.

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#include <DFRobot_GP8XXX.h>

DFRobot_GP8211S GP8211S;

void setup() {

 Serial.begin(9600);

 while(GP8211S.begin()!=0){
   Serial.println("Communication with the device has encountered a failure. Please verify the integrity of the connection or ensure that the device address is properly configured.");
   delay(1000);
   
 }
 GP8211S.setDACOutRange(GP8211S.eOutputRange5V);
 /**
  * @brief. Configuring different channel outputs for DAC values
  * @param data. Data values corresponding to voltage values
  * @n （0 - 32767）.This module is a 15-bit precision DAC module, hence the values ranging from 0 to 32767 correspond to voltages of 0-10V respectively.
  */

}

void loop() {

 for (int value=0; value<33; value++){ 
    
 Serial.print("Value to write:");
 Serial.println(value*1000);
 GP8211S.setDACOutVoltage(value*1000);
 delay(200);
 }
 
 for (int value=32; value>0; value--){ 
   
 Serial.print("Value to write:");
 Serial.println(value*1000);
 GP8211S.setDACOutVoltage(value*1000);
 delay(200);
 }
}
 

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