ATXMEGA256A3B-MH Atmel, ATXMEGA256A3B-MH Datasheet - Page 281

• 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

24.11.3
24.11.4
24.11.5
8077H–AVR–12/09
REFRESH - SDRAM Refresh Period Register
INITDLY - SDRAM Initialization Delay Register
SDRAMCTRLB - SDRAM Control Register B
• Bit 15:10 - Reserved
These bits are reserved and will always be read as zero.
• Bit 9:0 - REFRESH[9:0]: SDRAM Refresh Period
This register sets the refresh period as a number of Peripheral 2x clock (CLK
EBI is busy with another external memory access at time of refresh, up to 4 refresh will be
remembered and given at the first available time.
• Bit 15:14 - Reserved
These bits are reserved and will always be read as zero.
• Bit 13:0 - INITDLY[13:0]: SDRAM Initialization Delay
This register is used to delay the initialisation sequence after the controller is enabled until all
voltages are stabilized and the SDRAM clock has been running long enough to take the SDRAM
chip through its initialisation sequence. The initialisation sequence includes pre-charge all banks
to their idle state issuing an auto-refresh cycle and then loading the mode register. The setting in
this register is as a number of Peripheral 2x clock cycles.
Bit
+0x04
+0x05
Read/Write
Initial Value
Bit
+0x06
+0x07
Read/Write
Initial Value
Bit
+0x08
Read/Write
Initial Value
R/W
R/W
R/W
15
15
R
R
7
0
0
7
0
0
7
0
-
-
MRDLY[1:0]
R/W
R/W
R/W
14
14
R
R
6
0
0
6
0
0
6
0
-
-
R/W
R/W
R/W
R/W
13
13
R
5
0
5
0
0
5
0
0
-
ROWCYCDLY[2:0]
R/W
R/W
R/W
R/W
12
12
R
4
0
4
0
0
4
0
0
REFRESH[7:0]
-
INITDLY[7:0]
R/W
R/W
R/W
R/W
11
11
R
3
0
3
0
0
3
0
0
-
INITDLY[9:8]
R/W
R/W
R/W
R/W
10
10
R
2
0
2
0
0
2
0
0
-
RPDLY[2:0]
R/W
R/W
R/W
R/W
R/W
REFRESH[9:8]
1
0
1
9
0
0
1
9
0
0
R/W
R/W
R/W
R/W
R/W
0
0
0
8
0
0
0
8
0
0
XMEGA A
PER
) cycles. If the
SDRAMCTRLB
REFRESHL
REFRESHH
INITDLYL
INITDLYH
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