How to Monitoring the lines between an Atmega8 and a LCD using Atmega32
Can I connect En to Interrupt-0 pin and in falling edge read DB4....7?


Essentially, yes. You also want to read the RS pin to see if the data is for control or text.


  And another question, when we send data to LCD in 4bit-packs, we send high nibble first or we send low nibble?


Higher nibble first.