CODEWITHSUNDEEP
arduinomicrocontrolleratmegaadc
Oli
Oli

Reputation: 1393

Arduino analogRead() reset microcontroller

I am using Atmega328 with arduino bootloader. My whole code is working fine. Now I need to use analogRead() to get ADC values, but as soon as PC see analogRead(), it restart microcontroller. Here is the sample code.

void setup() {
  Serial.begin(19200);
  while(!Serial);
  Serial.println("Setup finish");
  delay(200);
}

void loop() {
  Serial.println("Reading analong Values");
  uint16_t a = analogRead(A0);
  Serial.println(a);
  delay(1000);
}

The output is, 

Setup finish
�Setup finish
�Setup finish
�Setup finish
�Setup finish
�Setup finish
�Setup finish
�Setup finish
�

I also tried to put delay() before and after it but no vain. How to fix it. Thank you.

Update: I have tried 0 instead of A0, but no vain.

Update: The problem all boils down to voltage selection(3.3 or 5V) switch on FTDI programmer. Setting it to 5V works perfectly, but switching it to 3.3V, the problem appears again.

Upvotes: 1

Views: 2213

Answers (4)

Yusuf Maged
Yusuf Maged

Reputation: 11

I recommend that instead of writing uint16_t a = analogRead(A0), you should declare the input of A0 as a variable and call it later in the program.Also, there is a mistake in the void setup() section which is that you wrote the while loop with the condition and the ended the line with a semi colon. You should have written the actions that are to be done if the statement is true between curly brackets

Upvotes: 1

Oli
Oli

Reputation: 1393

The inductor between power supply 3.3V and AVcc pin was the problem of analogRead() reset. The purpose of this inductor is mentioned here, Inductor purpose. But short-circuiting the inductor clears the problem.

Upvotes: 1

Yann Vernier
Yann Vernier

Reputation: 15887

Since analogRead only works on analog input pins, it takes the channel number, not a pin number. Try passing 0 rather than A0. It likely fails because A0 has a higher number (as a digital pin) than the number of analog input channels, causing an out of bounds error.

Upvotes: 0

Mike
Mike

Reputation: 637

From the Arduino site here:

DEFAULT: the default analog reference of 5 volts (on 5V Arduino boards) or 3.3 volts (on 3.3V Arduino boards)

INTERNAL: an built-in reference, equal to 1.1 volts on the ATmega168 or ATmega328 and 2.56 volts on the ATmega8 (not available on the Arduino Mega)

This clearly shows that atmega328 you are using requires an internal reference to 1.1v when reading off the analog inputs. It is probably restarting because when using analogReference(DEFAULT); the atmega328 doesn't know how to properly decode the signal and it crashes out.

Upvotes: 0

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