AtTiny45 read lag?

Question

I have set up 2 AtTiny45 setup like this (The left one is also connected to power): from which one (the left one) is generating a signal which is (when measured) looking like this: 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:

The tinys are both running at 8Mhz speed.

Answer 1

Based on the code, I am guessing you are using the Arduino libraries?

If so, then looking at your breadboard and your code, it looks like you might just have your pins reversed.

In Arduino-land on an ATTINY 45, the "pin" as used for for pinMode() and readDigital() does not correspond to the actual physical numbered pins on the device...

(from this helpful site)

Maybe try swapping the pin values in your code to this...

int inPin = 4;
int outPin = 3;

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

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

...and attach your scope to physical pin #2 (Arduino pin #3) on the device and see what you get.

Also note that the digitalRead() and digitalWrite() functions in thew Arduino library are notoriously slow, so depending on how fast the signal that you are trying to duplicate changes, you might want to look into the DigitalWriteFast library or direct port manipulation.

Answer 2

Try adding a "proper reset circuitry":

^{simulate this circuit – Schematic created using CircuitLab}

You dont mention from where you are powering your board, there may be to much noise and its reseting your MCU. By adding a stronger pull-up and a capacitor you're filtering out the noise that may appear on your power-supply or RESET line.