Sensor "persistence"?

[iahim67]

Amazing! You were absolutely right! I tried a simple LED blink like below, it only works once after the code upload. No matter how many times I power cycle after that, it will not work any more. What could be wrong with this Arduino Mini? It is the original Arduino Mini from Farnell ...

/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.

  Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO 
  it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
  the correct LED pin independent of which board is used.
  If you want to know what pin the on-board LED is connected to on your Arduino model, check
  the Technical Specs of your board  at https://www.arduino.cc/en/Main/Products
  
  This example code is in the public domain.

  modified 8 May 2014
  by Scott Fitzgerald
  
  modified 2 Sep 2016
  by Arturo Guadalupi
  
  modified 8 Sep 2016
  by Colby Newman
*/


// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(8, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(8, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(8, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}```

[iahim67]

Many thanks nevertheless:-)
I use Arduino 1.8.2

[tbowmo]

I have no idea what could be wrong with it..

Have you checked the soldering of the board? Tried another powersupply?

[iahim67]

Forgot to tell I have a few such Arduino Mini, all have the same issue!
Might have something to do with both the way I have connected the power and the reset, like here, "Connecting the Arduino Mini and Mini USB Adapter":

https://www.arduino.cc/en/Guide/ArduinoMini

Power to the Arduino (+5V) comes from the USB Adapter while reset goes through a capacitor.
I will abandon this setup and use a nano based sensor for now.

[iahim67]

I think the RESET could be the problem but I cannot find the schematics of this Arduino Mini to determine the precise source of the problem.
I'll use the Nano or the Pro in the future ... but thanks anyway, it was instructive!

[tbowmo]

Have you tried just supplying it with 5V, without the reset attached?

[iahim67]

Yes, I did, no change.
I have removed the capacitor on the RESET pin and I have pressed the RESET button on the Mini, nothing happens to my surprise.
I shall try to use a different 5V power supply instead of supplying the Mini from the USB adapter. Eventually remove every wire between the Mini and the USB adapter and use an external 5V supply.

[iahim67]

I have re-wired everything and it works now if I remove the wire from the USB Adapter "EXT. RESET" signal to the 100nF capacitor connected to the Arduino RESET pin - after the code upload.
I guess we can say "solved", I still can use the Arduino Mini if I remove either the RESET capacitor or the wire to this capacitor, like in the attached picture ... nice help on this forum anyway:-)

[tbowmo]

@iahim67

thanks for the feedback, and good that you got it working finally :)

[iahim67]

One more thing :simple_smile: , this is the Arduino Mini schematics if someone needs it (not very easy to find):