ATxmega256A3BU Atmel Corporation, ATxmega256A3BU Datasheet - Page 220

• Manufacturer Part Number: ATxmega256A3BU
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3BU

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 47
• Ext Interrupts: 49
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 8
• Twi (i2c): 2
• Uart: 6
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

18.3.7
18.3.8
18.3.9
8331A–AVR–07/11
CNTH – Counter Register High
PERL – Period Register Low
PERH – Period Register High
• Bit 7:0 - CNT[7:0]: Counter Value Low Byte
These bits hold the LSB of the 16-bit real-time counter value.
• Bit 7:0 – CNT[15:8]: Counter Value High Byte
These bits hold the MSB of the 16-bit real-time counter value.
The PERH and PERL register pair represents the 16-bit value, PER. PER is constantly com-
pared with the counter value (CNT). A match will set OVFIF in the INTFLAGS register and clear
CNT. Reading and writing 16-bit values requires special attention. Refer to
Registers” on page 12
Due to synchronization between the RTC clock and system clock domains, there is a latency of
two RTC clock cycles from updating the register until this has an effect. Application software
needs to check that the SYNCBUSY flag in the
cleared before writing to this register.
• Bit 7:0 – PER[7:0]: Period Low Byte
These bits hold the LSB of the 16-bit RTC TOP value.
• Bits 7:0 – PER[15:8]: Period High Byte
These bits hold the MSB of the 16-bit RTC TOP value.
Bit
+0x09
Read/Write
Initial Value
Bit
+0x0B
Read/Write
Initial Value
Bit
+0x0A
Read/Write
Initial Value
R/W
R/W
R/W
7
0
7
1
7
1
R/W
for details.
R/W
R/W
6
0
6
1
6
1
R/W
R/W
R/W
5
0
5
1
5
1
R/W
R/W
R/W
4
0
4
1
4
1
CNT[15:8]
PER[15:8]
PER[7:0]
”STATUS – Status Register” on page 218
R/W
R/W
R/W
Atmel AVR XMEGA AU
3
0
3
1
3
1
R/W
R/W
R/W
2
0
2
1
2
1
R/W
R/W
R/W
1
0
1
1
1
1
”Accessing 16-bit
R/W
R/W
R/W
0
0
0
1
0
1
CNTH
PERL
PERH
220
is