ATtiny85 I²C Slave übernimmt empfangenen Wert nicht.

#define I2C_SLAVE_ADDRESS 0x8 // the 7-bit address (remember to change this when adapting this example)

// Get this from https://github.com/rambo/TinyWire

#include <TinyWireS.h>

#include <Arduino.h>

// The default buffer size, Can't recall the scope of defines right now

#ifndef TWI_RX_BUFFER_SIZE

#define TWI_RX_BUFFER_SIZE ( 16 )

#endif

volatile int pwm = 150;

/**

 * This is called for each read request we receive, never put more than one byte of data (with TinyWireS.send) to the 

 * send-buffer when using this callback

 */

void requestEvent()

{  

    TinyWireS.send(pwm);

}

/**

 * The I2C data received -handler

 *

 * This needs to complete before the next incoming transaction (start, data, restart/stop) on the bus does

 * so be quick, set flags for long running tasks to be called from the mainloop instead of running them directly,

 */

 void receiveEvent(uint8_t howMany)

{ 

    digitalWrite(3,HIGH);

    if (howMany < 1)

    {

        // Sanity-check

        return;

    }

    if (howMany > TWI_RX_BUFFER_SIZE)

    {

        // Also insane number

        return;

    }

    // ignore write address

    TinyWireS.receive();

    howMany--;

    if (!howMany)

    {

        // This write was only to set the buffer for next read

        return;

    }

    while(howMany--)

    {

      byte recv = TinyWireS.receive();

      pwm = recv;  

    }

}

void setup()

{

    pinMode(1, OUTPUT); // OC1A, also The only HW-PWM -pin supported by the tiny core analogWrite

    pinMode(3, OUTPUT);

    /**

     * Reminder: taking care of pull-ups is the masters job

     */

    TinyWireS.begin(I2C_SLAVE_ADDRESS);

    TinyWireS.onReceive(receiveEvent);

    TinyWireS.onRequest(requestEvent);

}

void loop()

{

    /**

     * This is the only way we can detect stop condition (http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&p=984716&sid=82e9dc7299a8243b86cf7969dd41b5b5#984716)

     * it needs to be called in a very tight loop in order not to miss any (REMINDER: Do *not* use delay() anywhere, use tws_delay() instead).

     * It will call the function registered via TinyWireS.onReceive(); if there is data in the buffer on stop.

     */

    TinyWireS_stop_check();

    analogWrite(1, pwm);

}

int pwm = 0;

void setup() {

 Serial.begin(115200); /* begin serial for debug */

 Wire.begin(); /* join i2c bus with SDA=D1 and SCL=D2 of NodeMCU */

}

void loop() {

if(pwm < 255){

  pwm +=5;

  Serial.printf("Dimming up... Next pwm value : %i", pwm);

  Serial.println();

}

else if (pwm >= 255){

  pwm =0;

  Serial.println("Reset PWM");

}

 Wire.beginTransmission(8); /* begin with device address 8 */

 Wire.write(pwm);  /* sends hello string */

 Wire.endTransmission();    /* stop transmitting */

 delay(500);

 Serial.printf("Sent pwm value : %i", pwm);;

 Serial.println();

Wire.requestFrom(8, 1);    // request 6 bytes from slave device #8

  while (Wire.available()) { // slave may send less than requested

    byte c = Wire.read(); // receive a byte as character

    Serial.println("Requested value from Slave:");

    Serial.print(c);         // print the character

    Serial.println();

  }

  delay(500);

}