Serial Communication with Attiny85

Development Tools IDE 1.x
1

I'm trying to use serial communication on an Attiny85, but I haven't been able to get the SoftwareSerial library to work with it.

I'm using an Arduino as an ISP, and trying to upload the simple script

#include <SoftwareSerial.h>

void setup() {
  
}

void loop() {
  
}

gives the errors:

In file included from AttinySoftwareSerial.ino:1:
C:\Program Files (x86)\Arduino\libraries\SoftwareSerial/SoftwareSerial.h:48: error: expected class-name before '{' token
C:\Program Files (x86)\Arduino\libraries\SoftwareSerial/SoftwareSerial.h:92: error: 'size_t' does not name a type
C:\Program Files (x86)\Arduino\libraries\SoftwareSerial/SoftwareSerial.h:97: error: 'Print' has not been declared

I'm confused why this is, because I can upload the code just fine onto the Arduino itself, and I've also been able to use the Arduino to upload the Blink example onto the Attiny. Any help would be appreciated, thanks!

2

I turned on verbose logging and got all sorts of additional errors. It appears that the built-in SoftwareSerial library relies on other parts of the Arduino library that are not compatible with the ATtiny85. I think you have to find a third-party software-serial library designed to run on the ATtiny85.

3

That sounds very strange.
I have never had any problems with ATtiny85/softwareserial

I use this core for the tiny's

https://code.google.com/p/arduino-tiny/

If you just want serial output the core has a built in serial, no librarys need, so you can just do:

void setup() {
 Serial.begin(9600);
}

void loop() {
Serial.println("Testing...");
delay(1000);
}

The serial output will be on pin pb3

More on the subject:

http://www.ernstc.dk/arduino/tinycom.html

4

Erni: Those are the drivers I'm using (1.0)

I turned on verbose output, and now the error is

In file included from AttinySoftwareSerial.ino:1:
C:\Program Files (x86)\Arduino\libraries\SoftwareSerial/SoftwareSerial.h:36:20: warning: Stream.h: No such file or directory
In file included from AttinySoftwareSerial.ino:1:
C:\Program Files (x86)\Arduino\libraries\SoftwareSerial/SoftwareSerial.h:48: error: expected class-name before '{' token
C:\Program Files (x86)\Arduino\libraries\SoftwareSerial/SoftwareSerial.h:92: error: 'size_t' does not name a type
C:\Program Files (x86)\Arduino\libraries\SoftwareSerial/SoftwareSerial.h:97: error: 'Print' has not been declared

The problem seems to be that SoftwareSerial can't find Stream.h, which would also explain the errors on lines 48 and 97, since Stream and Print are both parts of that library. I tried uploading a dummy file that includes Stream.h to the attiny and they seem to compatible.

Any ideas on how to fix this or why this is happening would be appreciated.

5

trueblue:
Erni: Those are the drivers I'm using (1.0)

Then just use Serial instead of SoftwareSerial.

6

Erni: Those are the drivers I'm using (1.0)

I'm not sure what that means.

Do you mean Arduino IDE version 1.0