ATmega169 supports 100 segments. Thus not all of the 120 segments on the LCD-dis- play can be shown simultaneously. Five of the 30 segment-pins on the LCD display has to be left unconnected. The LCD-pins that are not connected are pin #: 3, 24, 30, 31, and 32. See Technical Specifications for an overview of the excluded segments.
In order to use some of the segments on the LCD display that by default are not included or in order to use some of the segment pins as ordinary I/O-pins, use a custom strap between the two 34-pin headers. These to headers are lined up so they will fit in to a 2.54 mm pitch grid for easy connecting, e.g., a experiment board on top of them.
The pin out for these two headers (Figure 1) can be found on the bottom-side of the STK502-PCB or in Complete Schematics.
This hardware configuration will give a certain bit-mapping between the bits in the ATmega169 LCDDRx Register and the segments on the STK502 LCD. See STK502 LCD Bit Mapping.