i got this diagram from another thread in this forum. mu doubt is what is the SIGNAL FROM AVR means in this diagram.

please help me...

 

I don't know what AVR stands for in that circuit. But its a output signal from a controller for that h-drive circuit.

 

AVR is one kinds of MCU(microcontroller), like as 8051 series, pic, ARM, they are different level of MCU.

If you want to see more details about AVR, please take a look here:
Atmel AVR.
From Wikipedia, the free encyclopedia.
http://en.wikipedia.org/wiki/Atmel_AVR