ATMEGA644V-10MU Atmel, ATMEGA644V-10MU Datasheet - Page 179

• Manufacturer Part Number: ATMEGA644V-10MU
• Description: IC AVR MCU FLASH 64K 44-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644V-10MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 10MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-VQFN Exposed Pad
• Package: 44QFN EP
• Device Core: AVR
• Family Name: ATmega
• Maximum Speed: 10 MHz
• Operating Supply Voltage: 2.5|3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 32
• Interface Type: JTAG/SPI/TWI/USART
• On-chip Adc: 8-chx10-bit
• Number Of Timers: 3
• Processor Series: ATMEGA64x
• Core: AVR8
• Data Ram Size: 4 KB
• Maximum Clock Frequency: 20 MHz
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• For Use With: ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK600 - DEV KIT FOR AVR/AVR32770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

17.8.3
2593N–AVR–07/10
Asynchronous Operational Range
Figure 17-7. Stop Bit Sampling and Next Start Bit Sampling
The same majority voting is done to the stop bit as done for the other bits in the frame. If the stop
bit is registered to have a logic 0 value, the Frame Error (FEn) Flag will be set.
A new high to low transition indicating the start bit of a new frame can come right after the last of
the bits used for majority voting. For Normal Speed mode, the first low level sample can be at
point marked (A) in
(B). (C) marks a stop bit of full length. The early start bit detection influences the operational
range of the Receiver.
The operational range of the Receiver is dependent on the mismatch between the received bit
rate and the internally generated baud rate. If the Transmitter is sending frames at too fast or too
slow bit rates, or the internally generated baud rate of the Receiver does not have a similar (see
Table
bit.
The following equations can be used to calculate the ratio of the incoming data rate and internal
receiver baud rate.
D
S
S
S
R
Table 17-2
that Normal Speed mode has higher toleration of baud rate variations.
F
M
slow
17-2) base frequency, the Receiver will not be able to synchronize the frames to the start
(U2X = 0)
(U2X = 1)
Sample
Sample
RxD
R
slow
and
Sum of character size and parity size (D = 5 to 10 bit)
Samples per bit. S = 16 for Normal Speed mode and S = 8 for Double Speed
mode.
First sample number used for majority voting. S
for Double Speed mode.
Middle sample number used for majority voting. S
S
is the ratio of the slowest incoming data rate that can be accepted in relation to the
receiver baud rate. R
accepted in relation to the receiver baud rate.
=
M
Table 17-3
= 5 for Double Speed mode.
------------------------------------------ -
S 1
–
Figure
(
D
+
1
1
+
D S ⋅
1
2
17-7. For Double Speed mode the first low level must be delayed to
list the maximum receiver baud rate error that can be tolerated. Note
)S
+
3
2
S
F
4
fast
5
3
is the ratio of the fastest incoming data rate that can be
6
7
4
8
STOP 1
9
5
10
R
fast
(A)
0/1
6
=
0/1
F
-----------------------------------
(
= 8 for normal speed and S
D
M
(B)
0/1
0/1
(
+
= 9 for normal speed and
D
1
+
)S
2
)S
+
ATmega644
S
M
(C)
F
179
= 4