Steps for using Softwareserial with attiny


I’ve successfully used the atTiny before, but I need to see the values of the sensors I am using and I am trying to do this using SoftwareSerial and not having any luck.

Here are my steps (based on the HLT description/wiring:
I am using a Duemilanove as Arduino ISP, then burning bootloader to the atTiny45 chip at 8 mHZ
then I try to upload the software serial code with the aTtiny45(8mHz internal clock) board selected still. it doesn’t work when i try to choose the aTtiny45 with arduino as isp. i have a 10uF cap on the board between reset and ground after uploading the isp

#include <SoftwareSerial.h>

SoftwareSerial mySerial(0, 1); // RX, TX

void setup()
// set the data rate for the SoftwareSerial port
mySerial.println(“Hello, world?”);
pinMode(0, INPUT);
pinMode(1, OUTPUT);
pinMode(3, INPUT_PULLUP);

void loop() // run over and over
int sensorValue = analogRead(3);


i get the following error, which is normal:
avrdude: please define PAGEL and BS2 signals in the configuration file for part ATtiny45
avrdude: please define PAGEL and BS2 signals in the configuration file for part ATtiny45

but nothing in the serial monitor, except for this when i try different baudrates: ÿÿÿÿÿÿÿÿÿ

does any one have code that they know works? and/or am i doing something out of order? i’ve tried all the different pin connections, uploading order etc


That core is reported to not work with Software serial, install the latest from here;

This error "avrdude: please define PAGEL and BS2 signals in the configuration file for part ATtiny45"

Can be ignored, just forget it is there it does no harm.

thanks i downloaded the new core you recommended, and i am still not seeing anything. does the code look alright? i tried the code from the funduino example as well, do i need to open the serial port somehow, and should i have the 45 (with 8MHz clock) board selected when uploading the serial sketch? it says it burned bootloader successfully.

i know the error can be ignored but it is still not working.

I ran into a similar problem a while back while trying to use NewSoftSerial on my ATTiny85's... It worked fine for me on Arduino 1.0 after using the update hardware files, but I still prefer to use the AVRISP sketch from Arduino 0022. I didn't have to use a 10uf cap on my UNO, but you should have one just in case. Lastly, you don't need to define your serial pins as inputs/outputs, just start "mySerial" and it should all work. Let me know if you have any further problems

Cheers! Mr_E :)

How do you connect the tx pin on Attiny85 to your computer? I have succesfully used a cheap CP2102 like this one and the updated core from


The subject is discussede in this thread:,109081.0.html

And finally, if you only need one way communication (from the tiny to your PC) you don't need a library, you can just use TinyDebugSerial