Voltage resetting with MCP4725

Projects General Guidance
1

I am using an MCP4725 module with a Mega board. I just need to have a set voltage output.

When I input the desired voltage, I can measure the correct voltage for about a second, and then in the serial monitor I see a command that sets the voltage at 0, and then the measured voltage goes to 0. I have tried everything, swapping all components, but the problem persists.

Any help would be appreciated.

2

Hello aardvarken
What a nice name.

Welcome to the worldbest Arduino forum ever.

Post your sketch, well formated, with well-tempered comments and in so called code tags "< code >" and schematic to see how we can help.

Have a nice day and enjoy coding in C++.

3

Thank you.

Here is the sketch.

#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac;

void setup() {
  Serial.begin(9600);
  Wire.begin();
  dac.begin(0x62);  // Use the I2C address 0x62 for the MCP4725 module
}

void loop() {
  if (Serial.available()) {
    float voltageValue = Serial.parseFloat();  // Read the voltage value from the Serial Monitor
    
    // Ensure the voltage value is within the valid range (0 to 5)
    voltageValue = constrain(voltageValue, 0.0, 5.0);
    
    // Convert the voltage to the corresponding DAC value (0 to 4095)
    int dacValue = voltageValue * 4095.0 / 5.0;
    
    // Set the DAC output value and update EEPROM
    dac.setVoltage(dacValue, true);  // 'true' means update the EEPROM
    
    Serial.print("Output voltage set to: ");
    Serial.print(voltageValue, 2);
    Serial.println(" V");
  }
}
4

Hello Erdferkel

Take a view here to gain the knowledge.

5

I tried a different variation of the code without that command, and I get the same problem. It accepts my input voltage, and then after about a second it changes it to 0 v.

#include <Wire.h>
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac;

void setup() {
  Serial.begin(9600);
  dac.begin(0x62); // Change this to your I2C address if needed
}

void loop() {
  Serial.println("Enter desired voltage (0-50 for 0.0-5.0V): ");
  while (!Serial.available()) {
    // Wait for user input
  }
  
  int targetVoltageRaw = Serial.parseInt();
  
  if (targetVoltageRaw >= 0 && targetVoltageRaw <= 50) {
    float targetVoltage = targetVoltageRaw / 10.0; // Convert to 0.0-5.0V range
    dac.setVoltage(targetVoltage * 4095.0 / 5.0, false);
    Serial.print("Set Voltage: ");
    Serial.print(targetVoltage, 1);
    Serial.println(" V");
  } else {
    Serial.println("Invalid input or voltage out of range. Please enter a valid voltage (0-50 for 0.0-5.0V).");
  }
}
6

Set the line-ending in serial monitor to No Line Ending.

Or start using a better approach based on Serial Input Basics - updated.

7

Thank you very much. That fixed the problem.

I am just learning how to code the arduino (out of necessity), so thank you for the solution and the advice.

8

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