Atmel AVR1924
7
8370C-AVR-12/11
6 Miscellaneous I/O
6.1 Mechanical button switches
Eight mechanical button switches are connected to XMEGA PORTD(PD0:PD5) and
PORTR(PR0:PR1). Internal pull-ups should be enabled to detect when the buttons
are pushed, as they short the respective line to GND.
NOTE Buttons share the pins with the J3 header: Pushing the buttons potentially affects
communication or other functionality on these pins.
6.2 LEDs
Eight yellow LEDs are connected to XMEGA PORTE. The LEDs are active low, and
thus light up when the respective lines are output low by the XMEGA.
One green and one red LED are inside the same package and therefore the colors
can be mixed to orange when both are activated. The red LED can be activated by
driving the connected I/O line to GND. The green LED is controlled via a FET and is
by default on when the board is powered. However this power indicator LED can also
be turned off by driving the gate of the FET to GND. Both LEDs are controlled by the
Atmel AT32UC3B1256. The default firmware will use the red LED to signal activity on
the UART to USB bridge by toggling the LED.
6.3 Analog I/O
An NTC temperature sensor and a light sensor are connected to PORTB on PB0 and
PB1, respectively. These analog references can be used as input to the ADC.
An audio amplifier (and mono speaker) is connected to PORTB on pin PB2. This pin
is connected to the XMEGA DAC, and thus offers a way to generate sound.
