I have set up 2 AtTiny45 setup like this (The left one is also connected to power):
![](https://i.stack.imgur.com/iZ69r.png)
from which one (the left one) is generating a signal which is (when measured) looking like this:
![](https://i.stack.imgur.com/K94UV.jpg)
The second one now runs this code to just pass the signal through from an input to an output:

```
int inPin = 3;
int outPin = 4;

void setup() {
  pinMode(inPin, INPUT);
  digitalWrite(inPin, HIGH);
  pinMode(outPin, OUTPUT);
}

void loop() {
  digitalWrite(outPin, digitalRead(inPin));
}

```

But instead of looking like the original it is looking like this:
![](https://i.stack.imgur.com/hqsKf.jpg)

The tinys are both running at 8Mhz speed.