ATMEGA128RZAV-8MU Atmel, ATMEGA128RZAV-8MU Datasheet - Page 208

• Manufacturer Part Number: ATMEGA128RZAV-8MU
• Description: MCU ATMEGA1281/AT86RF230 64-QFN
• Manufacturer: Atmel
• Series: ATMEGAr

Specifications of ATMEGA128RZAV-8MU

• Frequency: 2.4GHz
• Data Rate - Maximum: 2Mbps
• Modulation Or Protocol: 802.15.4 Zigbee
• Applications: General Purpose
• Power - Output: 3dBm
• Sensitivity: -101dBm
• Voltage - Supply: 1.8 V ~ 3.6 V
• Data Interface: PCB, Surface Mount
• Memory Size: 128kB Flash, 4kB EEPROM, 8kB RAM
• Antenna Connector: PCB, Surface Mount
• Package / Case: 64-QFN
• For Use With: ATAVRISP2 - PROGRAMMER AVR IN SYSTEMATJTAGICE2 - AVR ON-CHIP D-BUG SYSTEMATSTK501 - ADAPTER KIT FOR 64PIN AVR MCUATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Operating Temperature: -
• Current - Transmitting: -
• Current - Receiving: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

21.2.2
21.2.3
2549M–AVR–09/10
Double Speed Operation (U2Xn)
External Clock
Table 21-1.
Note:
Some examples of UBRRn values for some system clock frequencies are found in
page
The transfer rate can be doubled by setting the U2Xn bit in UCSRnA. Setting this bit only has
effect for the asynchronous operation. Set this bit to zero when using synchronous operation.
Setting this bit will reduce the divisor of the baud rate divider from 16 to 8, effectively doubling
the transfer rate for asynchronous communication. Note however that the Receiver will in this
case only use half the number of samples (reduced from 16 to 8) for data sampling and clock
recovery, and therefore a more accurate baud rate setting and system clock are required when
this mode is used. For the Transmitter, there are no downsides.
External clocking is used by the synchronous slave modes of operation. The description in this
section refers to
External clock input from the XCKn pin is sampled by a synchronization register to minimize the
chance of meta-stability. The output from the synchronization register must then pass through
an edge detector before it can be used by the Transmitter and Receiver. This process intro-
Asynchronous Normal
mode (U2Xn = 0)
Asynchronous Double
Speed mode (U2Xn =
1)
Synchronous Master
mode
Operating Mode
227.
BAUD
f
UBRRn
OSC
1. The baud rate is defined to be the transfer rate in bit per second (bps).
Equations for Calculating Baud Rate Register Setting
Figure 21-2 on page 207
Baud rate (in bits per second, bps).
System Oscillator clock frequency.
Contents of the UBRRHn and UBRRLn Registers, (0-4095).
BAUD
BAUD
BAUD
Equation for Calculating
ATmega640/1280/1281/2560/2561
Baud Rate
=
=
=
----------------------------------------- -
16 UBRRn
-------------------------------------- -
8 UBRRn
-------------------------------------- -
2 UBRRn
(
(
(
for details.
f
f
f
OSC
OSC
OSC
(1)
+
+
+
1
1
1
)
)
)
UBRRn
UBRRn
UBRRn
Equation for Calculating
UBRR Value
=
=
=
----------------------- - 1
16BAUD
------------------- - 1
8BAUD
------------------- - 1
2BAUD
f
f
f
OSC
OSC
OSC
–
–
–
Table 21-9 on
208