Serial on AtTiny85

Hi all,

First of all; I rather new to electronics (and this Forum), so please keep that in mind! :)

I'm trying to program an AtTiny85 via my Arduino Uno R3. Everything works fine and fast. But...

Here comes my question; I would like to use "Serial.println" function in the Tiny. Only for debugging. But I unable to get a proper response from the tiny! I only get "ÿ" strings as a result. I know this means -1, no data available.

Using the following board setting: "Attiny 85 @ 8 Mhz (internal oscillator; BOD disabled)"

Using the following setup: - TX port of the Tiny is connected to Pin1 (TX) of the Uno with an 100Ohm resistor. - Reset and GND are on my Uno connected with a 10uF condensator.

Using the following code:

void setup()
{  
  Serial.begin(9600);   
}
void loop()
{ 
  Serial.println("test ");
  delay(500);
}

...I 'discoved' when I press the reset button on the Uno -at the right time- the "test " message is shown in the Serial Monitor. So is there something wrong with the (auto) reset on my Uno?

I found several topics about this and tried many things but none didn't help me. Please help me!

Thanks a lot!

  • Reset and GND are on my Uno connected with a 10uF condensator.

It should be a jumper wire to keep the Uno in reset.

Alternative: remove the chip from your Uno And to be safe connect a resistor (330 .. 1000 ohm) between the ATtiny (PB3) and UNO (1) Edit: you have done that, great

Thanks for your reply!

It should be a jumper wire to keep the Uno in reset.

That was the problem! I've changed the condensator to a jumper. This is working! Awesome! Thanks!!

...but still; why are people telling that condensators or resistors are needed to keep the Uno in reset?

KiwiFreaK: ...but still; why are people telling that condensators or resistors are needed to keep the Uno in reset?

...to keep the Uno from [u]auto-resetting[/u]. Which is most definitely not the same as "keeping the Uno in reset".