Is my arduino dead? 5.5v applied to a4 pin for a sec

The cause during an experiment, I accidentally applied about 5.5 volt to an analog input pin for a few second. Everything seems to be fine, and I have a LCD hooked up to my arduino all the time and it still displays texts in the way I programmed, and I am able to upload sketch to the board.

The problem: 1, one of the input reading never goes to 0, even after I connected it to the ground. 2, I have a clocked timer running, but when it goes up to 60 second, it doesn't advance to 1 minute.

The question: Is my arduino dead, bad or whatever it's now, and is there a way for me to fit it up?

The 5.5V is not very high, are you sure it wasn't more ?

Which Arduino board are you using ? When an analog input is damaged, the whole analog section can be damaged. That is possible. I don't know about the timer.

Peter_n:
The 5.5V is not very high, are you sure it wasn’t more ?

Which Arduino board are you using ?
When an analog input is damaged, the whole analog section can be damaged. That is possible.
I don’t know about the timer.

maybe 6.0v, but definitely not higher than 7v. I am using nano; everything seems to be fine, except the 2 observed problems.

There are the code. a simple program with LCD for capacitor discharge testing.

#include "ClickButton.h"
#include <LiquidCrystal.h>

LiquidCrystal lcd(7,6,5,4,3,2);

//------------------------------------------------------------------------------------------------------
byte battery[8] = {
  0b01010,
  0b11111,
  0b10001,
  0b11111,
  0b10001,
  0b11111,
  0b10001,
  0b11111
};

ClickButton ba(9, LOW, CLICKBTN_PULLUP);
ClickButton bb(8, LOW, CLICKBTN_PULLUP);

int sec=0;
int Min=0;
int hr=0;
int halfDay=0;
int day=0;
int AmPm=0;
char* APM="AM";

int capPercent=0;
float capV=0;
int amp=0;
int mah=0;
long total=0;
float ref=0.80;

unsigned long nowtimer=0;
unsigned long pretimer=0;

//------------------------------------------------------------------------------------------------------
void setup()
{

  lcd.begin(16,2); 
  lcd.createChar(1, battery);

  ba.multiclickTime = 50;
  bb.multiclickTime = 50;    

}


//------------------------------------------------------------------------------------------------------
void loop()
{
  ba.Update();
  bb.Update();  

  if(AmPm==0) APM="AM";
  else APM="PM";
  
 
 
  
  float shunt = analogRead (A3);
  amp= shunt*5.0/1024.0*1000.0*ref;
  
  capV= analogRead (A5);
  capPercent= capV/1024.0*5.0/2.7*100.0*ref;
  
  
  mah=total/3600;
 
  

  nowtimer=millis();
  if(nowtimer-pretimer>=1000) {
    sec++;
    pretimer=nowtimer;   
 
 total= total + amp;   
    
  char buffer[17];
  sprintf(buffer, "A:%04d C:%02d %04d", amp, capPercent, mah);
  lcd.setCursor (0,1); 
  lcd.print (buffer);    
  
  

  char yyy[17];
  sprintf( yyy, "%c %02d:%02d:%02d:%02d %s", 0x01, day, hr, Min, sec, APM);
  lcd.setCursor (0,0); 
  lcd.print ( yyy );   

  
  }  

  if(sec==60){ 
    Min++;  
    sec=0; 
  }
  if(Min==60){ 
    hr++;  
    Min=0; 
  }
  if(hr==12){
    AmPm=!AmPm; 
    halfDay++; 
    hr=0;
  }
  if(halfDay==2){
    halfDay=0; 
    day++;
  }  


  //=====================

  



  //================================  

  if(ba.clicks==1) sec=0; Min=0;
  if(bb.clicks==1) total=0;  

  if(ba.clicks==-1) ;
  if(bb.clicks==-1) ;

}

//------------------------------------------------------------------------------------------------------

Was it a capacitor ? That has almost unlimited current. A capacitor with a voltage near 6V could indeed damage (a part of) the microcontroller. So yes, your Arduino Nano is probably broken =( (considering that half-broken is broken).

Did you build a project ? Which one ? I would like to see the schematic. Measuring a capacitor while the capacitor is not empty is an easy to make mistake. There should be some protection.

Peter_n: Was it a capacitor ? That has almost unlimited current. A capacitor with a voltage near 6V could indeed damage (a part of) the microcontroller. So yes, your Arduino Nano is probably broken =( (considering that half-broken is broken).

Did you build a project ? Which one ? I would like to see the schematic. Measuring a capacitor while the capacitor is not empty is an easy to make mistake. There should be some protection.

I think it's half-broken too, but is it even possible, half-broken?... I am measuring super capacitor of 100f 2.7 volt. I am using a DC-dc booster circuit to charge the capacitor through a 1 Ohm resistor, and by simply measure the voltage drop of that resistor, I can get how many current is getting in the capacitor, and then I just removed the power supply, and discharge the capacitor using the same 1 ohm resistor and measure the current as well.

guess, I need to get another one board again. Having broken 2 already.

Hi,

Regardless of what you did and what the damage is, damaging an analog input does not necessarily requires new board. I had boards with damaged analog, where I simply switched to another analog input. Normally not all are in use, and this will only require minor change in software. Try other inputs. They are probably still OK.

samtal:
Hi,

Regardless of what you did and what the damage is, damaging an analog input does not necessarily requires new board.
I had boards with damaged analog, where I simply switched to another analog input. Normally not all are in use, and this will only require minor change in software.
Try other inputs. They are probably still OK.

I know; I have tested all analog pins already; all the same.

Yes, half-broken is possible. I remember that others blow the analog section. But since you don't know what else is damaged, you have to replace it.

Can you make a schematic ? When you are only measuring with those pins, you can add a protection resistor of 1k or 4k7 to the Arduino input pins (analog or digital). The input will be protected, and the accuracy is almost the same.

Peter_n:
Yes, half-broken is possible. I remember that others blow the analog section. But since you don’t know what else is damaged, you have to replace it.

Can you make a schematic ?
When you are only measuring with those pins, you can add a protection resistor of 1k or 4k7 to the Arduino input pins (analog or digital). The input will be protected, and the accuracy is almost the same.

Okay. I don’t have another nano, but I do got few atmega823 chips. I am going to build my own board from now on. any tips? I want this to be breadboard friendly. the attached kk photo is the simple schematic. can you recommend me a free easy to use schematic making software? I use “Quite Universal Circuit Simulator” to make this schematic, but I don’t like it.

kk.jpg

When A5 and A4 are always used as inputs, use resistors of 4k7 to those analog input pins.

Pin A4 and A5 are also used for I2C, perhaps you can use other analog pins ? to be able to add I2C later.

Drawing a schematic is best done with Eagle. It is hard to get to know, but afterwards it was worth it. http://www.cadsoftusa.com/download-eagle/freeware/

To have something to start with, you can download the Eagle schematics from the Arduino pages. http://arduino.cc/en/Main/arduinoBoardNano

Peter_n: When A5 and A4 are always used as inputs, use resistors of 4k7 to those analog input pins.

Pin A4 and A5 are also used for I2C, perhaps you can use other analog pins ? to be able to add I2C later.

Drawing a schematic is best done with Eagle. It is hard to get to know, but afterwards it was worth it. http://www.cadsoftusa.com/download-eagle/freeware/

To have something to start with, you can download the Eagle schematics from the Arduino pages. http://arduino.cc/en/Main/arduinoBoardNano

great! thanks. I will be working on that. Eagle seems promising to me