Hardware 74HC164

Stefan Heinzmann's circuit requires only a 74HC164 8 bit shift register and a 10K trimpot to adjust the LCD's contrast.

The AVR's hardware requirements are 3 port pins:
PORTB bit 5 (LCDE) is connected to the E Clock (E) pin on the LCD module.
PORTB bit 6 (LCDDat) is connected to the register select (RS) pin on the LCD module and to the two data inputs (A and B) of
the 74HC164 shift register.
PORTB bit 7 (LCDClk) is connected to the CLK input of the 74HC164 shift register.
Any other three output port bits could be used.
It's a very simple circuit but adding a 0.1µf capacitor between the +5V and ground of the 74HC164 would be a good idea.
If you can't see any characters displayed on the LCD (and you've checked that the hardware and software are working) turn the LCD Contrast pot until you can see the characters.