Using the STK502 Top Module
STK502 User Guide
2-7
2528A–AVR–11/02
2.5
LCD Display
STK502 includes a LCD display. It features six 14-segments digits, and some additional
segments. All in all the display supports 120 segments. The display is designed for 3V
operating voltage. See the Technical Specifications for more details on the display.
2.5.1
Connecting the
STK502 LCD to the
ATmega169
The segment-pins from the ATmega169 are located at PORTA, PORTC, PORTD, and
PORTG. For simplicity in use they are all joined together on the header labeled “Seg-
ment pins from ATmega169”. The header next to it, labelled “STK502 LCD pins” holds
all the segments-pins for the LCD-display on the STK502.
By using the 34-lead cable that comes with the STK502-kit, the two pin-headers can be
connected, allowing the ATmega169 to control the LCD-display. See Figure 2-10.
Figure 2-10. Connecting the ATmega169 to the STK502 LCD
Caution: High-voltage Programming uses PORTB and PORTD. Be sure to disconnect
any LCD-display connected to the ATmega169 during the High-voltage Programming.
Otherwise the lifetime of the display may be reduced.
Caution: When using PORTA, PORTC, PORTD, or PORTG as regular I/O ports, the
corresponding LCD-segment pins must be disconnected from the ATmega169.
2.5.2
Default Segment
Configuration
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 2-11) can be found on the bottom-side of the
STK502-PCB or in Section 6 “Complete Schematics”.
