Peripherals; Crystals; Mechanical Buttons; Led - Atmel ATMEGA256RFR2 Xplained Pro User Manual

Pin on header
6
4.2

Peripherals

4.2.1

Crystals

The ATMEGA256RFR2 Xplained Pro kit contains two crystals that can be used as clock sources for the
ATmega256RFR2 device. Each crystal has a cut-strap next to it that can be used to measure the oscillator
allowance. This is done by cutting the strap and adding a resistor across the strap. More information about
oscillator allowance and safety factor can be found in appnote
Table 4-8. External 32.768kHz crystals
Pin on ATmega256RFR2
PG3
PG4
Table 4-9. External 16MHz crystals
Pin on ATmega256RFR2
XTAL1
XTAL2
4.2.2

Mechanical buttons

ATMEGA256RFR2 Xplained Pro contains two mechanical buttons. One button is the RESET button connected
to the ATmega256RFR2 reset line and the other is a generic user configurable button. When a button is
pressed it will drive the I/O line to GND.
Table 4-10. Mechanical buttons
Pin on ATmega256RFR2
RSTN
PE4
4.2.3

LED

There is one yellow LED available on the ATMEGA256RFR2 Xplained Pro board that can be turned on and off.
The LED can be activated by driving the connected I/O line to GND.
Table 4-11. LED connections
Pin on ATmega256RFR2
PB4
4.2.4 RF
The main feature of ATMEGA256RFR2 Xplained Pro is to show the RF capability of the ATmega256RFR2
device. This device has bidirectional differential antenna pins, which are fed through a balun (Johanson
Technology, 2450BM15A0015
switch (Skyworks Solutions Inc,
is driven by the DIG1 and DIG2 pins of the ATmega256RFR2 which feature Antenna Diversity to enable the
device to automatically select the best signal from two antennas (can also be selected manually). The output
of the switch is connected to a ceramic chip antenna (Johanson Technology,
connector for external antennas.
1
http://www.atmel.com/images/doc8333.pdf
2
http://www.johansontechnology.com/datasheets/balun-filter/2450BM15A0015.pdf
3
http://www.skyworksinc.com/uploads/documents/200252C.pdf
4
http://www.johansontechnology.com/images/stories/ip/rf-antennas/Antenna_2450AT18D0100_v3.pdf
ATmega256RFR2 Function
pin
GND
2
) to create a single unbalanced output/input. This kit has a passive analog RF
3
AS222-92LF ) connected to the unbalanced output of the balun. The switch
Atmel ATMEGA256RFR2 Xplained Pro [USER GUIDE]
Shared functionality
1
AVR4100
Function
TOSC2, crystal output
TOSC1, crystal input
Function
Crystal input
Crystal output
Silkscreen text
RESET
SW0
LED
Yellow LED
2540AT18D0100
4
) and a SMA
13
42079C-MCU-05/2013