ATXMEGA256A3B-MH Atmel, ATXMEGA256A3B-MH Datasheet - Page 237
![MCU AVR 256KB FLASH A3B 64-QFN](/photos/12/13/121326/313-64-qfn_sml.jpg)
ATXMEGA256A3B-MH
Manufacturer Part Number
ATXMEGA256A3B-MH
Description
MCU AVR 256KB FLASH A3B 64-QFN
Manufacturer
Atmel
Series
AVR® XMEGAr
Specifications of ATXMEGA256A3B-MH
Core Processor
AVR
Core Size
8/16-Bit
Speed
32MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, DMA, POR, PWM, WDT
Number Of I /o
49
Program Memory Size
256KB (128K x 16)
Program Memory Type
FLASH
Eeprom Size
4K x 8
Ram Size
16K x 8
Voltage - Supply (vcc/vdd)
1.6 V ~ 3.6 V
Data Converters
A/D 16x12b; D/A 2x12b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
64-MLF®, 64-QFN
Processor Series
ATXMEGA256x
Core
AVR8
Data Bus Width
8 bit, 16 bit
Data Ram Size
16 KB
Interface Type
I2C, SPI, USART
Maximum Clock Frequency
32 MHz
Number Of Programmable I/os
49
Number Of Timers
7
Operating Supply Voltage
1.6 V to 3.6 V
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
3rd Party Development Tools
EWAVR, EWAVR-BL
Development Tools By Supplier
ATAVRDRAGON, ATAVRISP2, ATAVRONEKIT
Minimum Operating Temperature
- 40 C
On-chip Adc
12 bit, 8 Channel
On-chip Dac
12 bit, 2 Channel
For Use With
ATAVRONEKIT - KIT AVR/AVR32 DEBUGGER/PROGRMMRATSTK600 - DEV KIT FOR AVR/AVR32770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAG770-1004 - ISP 4PORT FOR ATMEL AVR MCU SPI
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
ATXMEGA256A3B-MU
ATXMEGA256A3B-MU
ATXMEGA256A3B-MU
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATXMEGA256A3B-MH
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
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21.3
21.3.1
8077H–AVR–12/09
Clock Generation
Internal Clock Generation - The Fractional Baud Rate Generator
The clock used for baud rate generation, and for shifting and sampling data bits is generated
internally by the Fractional Baud Rate Generator or externally from the Transfer Clock (XCK)
pin. Five modes of clock generation are supported: Normal and Double Speed asynchronous
mode, Master and Slave synchronous mode, and Master SPI mode.
Figure 21-2. Clock Generation Logic, Block Diagram.I
The Fractional Baud Rate Generator is used for internal clock generation for asynchronous
modes, synchronous master mode, and SPI master mode operation. The generated output fre-
quency (f
Peripheral Clock frequency (f
baud rate (in bits per second) and for calculating the BSEL value for each mode of operation.
BSEL can be set to any value between 0 and 4095. It also show the maximum baud rate versus
peripheral clock speed.
Fractional baud rate generation can be used in asynchronous mode of operation to increase the
average resolution. A scale factor (BSCALE) allows the baud rate to be optionally left or right
scaled. Choosing a positive scale value will results in right scaling, which increase the period
and consequently reduce the frequency of the produced baud rate, without changing the resolu-
tion. If the scale value is negative the divider uses fractional arithmetic counting to increase the
resolution by distributing the fractional divide value over time. BSCALE can be set to any value
from -7 to +7, where 0 implies no scaling. There is a limit to how high the scale factor can be and
the value 2
see
PORT_INV
DDR_XCK
XCK
Pin
Section 21.9 on page 246
BAUD
BSCALE
xcko
xcki
) is given by the period setting (BSEL), an optional scale setting (BSACLE) and the
f
OSC
must be at least half of the minimum number of clock cycles a frame takes,
Baud Rate
Generator
Register
BSEL
Sync
PER
for more details.
).
f
BAUD
Table 21-1 on page 238
Detector
Edge
/2
/4
contains equations for calculating the
/2
DDR_XCK
CLK2X
XMEGA A
0
1
0
1
0
1
1
0
UMSEL [1]
txclk
rxclk
237
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