Using the STK525
2-14
STK525 Hardware User Guide
7608A–AVR–04/06
2.6
On-board Resources
2.6.1
Joystick
The 4+1 way joystick offers an easy user interface implementation for a USB application
(it can emulate mouse movements, keyboard inputs, etc.).
Pushing a push-button causes the corresponding signal to be pulled low, while releasing
(not pressed) causes an H.Z state on the signal. The user must enable internal pull-ups
on the input pins, removing the need for an external pull-up resistors on the push-button.
Figure 2-12 . Joystick Schematic
Figure 2-13 . Joystick Implementation
2.6.2
LEDs
The STK525 includes 4 green LEDs implemented on one line. They are connected to
the high nibble of “Port D” of AT90USBxxx (PORTD[4..7]).
To light On a LED, the corresponding port pin must drive to high level. To light Off a
LED, the corresponding port pin must drive a low level. It is the opposite method used in
STK500.
Select
5
Lef t
7
Up
3
Right
6
Down
4
Com1
1
Com2
2
SW3
TPA511G
PE[7..0]
PB[7..0]
PB5
PB6
PB7
PE4
PE5
Select
5
Lef t
7
Up
3
Right
6
Down
4
Com1
1
Com2
2
SW3
TPA511G
PE[7..0]
PB[7..0]
PB5
PB6
PB7
PE4
PE5
Select
5
Lef t
7
Up
3
Right
6
Down
4
Com1
1
Com2
2
SW3
TPA511G
PE[7..0]
PB[7..0]
PB5
PB6
PB7
PE4
PE5
