ATXMEGA128B1 Datasheet, PDF (13/138 Pages) ATMEL Corporation – 8/16-bit Atmel XMEGA B1 Microcontroller

Figure 7-2. Data memory map (hexadecimal address).
Byte Address
0
FFF
1000
17FF
2000
3FFF
ATxmega128B1
I/O Registers (4K)
EEPROM (2K)
RESERVED
Internal SRAM (8K)
Byte Address
0
FFF
1000
17FF
2000
2FFF
ATxmega64B1
I/O Registers (4KB)
EEPROM (2K)
RESERVED
Internal SRAM (4K)
7.6 EEPROM
XMEGA B1 devices have EEPROM for nonvolatile data storage. It is either addressable in a separate data space
(default) or memory mapped and accessed in normal data space. The EEPROM supports both byte and page access.
Memory mapped EEPROM allows highly efficient EEPROM reading and EEPROM buffer loading. When doing this,
EEPROM is accessible using load and store instructions. Memory mapped EEPROM will always start at hexadecimal
address 0x1000.
7.7 I/O Memory
The status and configuration registers for peripherals and modules, including the CPU, are addressable through I/O
memory locations. All I/O locations can be accessed by the load (LD/LDS/LDD) and store (ST/STS/STD) instructions,
which are used to transfer data between the 32 registers in the register file and the I/O memory. The IN and OUT
instructions can address I/O memory locations in the range of 0x00 to 0x3F directly. In the address range 0x00 - 0x1F,
single-cycle instructions for manipulation and checking of individual bits are available.
The I/O memory address for all peripherals and modules in XMEGA B1 is shown in the “Peripheral Module Address Map”
on page 59.
7.7.1
General Purpose I/O Registers
The lowest 4 I/O memory addresses are reserved as general purpose I/O registers. These registers can be used for
storing global variables and flags, as they are directly bit-accessible using the SBI, CBI, SBIS, and SBIC instructions.
7.8 Data Memory and Bus Arbitration
Since the data memory is organized as four separate sets of memories, the different bus masters (CPU, DMA controller
read and DMA controller write, etc.) can access different memory sections at the same time.
7.9 Memory Timing
Read and write access to the I/O memory takes one CPU clock cycle. A write to SRAM takes one cycle, and a read from
SRAM takes two cycles. For burst read (DMA), new data are available every cycle. EEPROM page load (write) takes one
cycle, and three cycles are required for read. For burst read, new data are available every second cycle. Refer to the
instruction summary for more details on instructions and instruction timing.
7.10
Device ID and Revision
Each device has a three-byte device ID. This ID identifies Atmel as the manufacturer of the device and the device type. A
separate register contains the revision number of the device.
XMEGA B1 [DATASHEET] 13
8330C–AVR–07/2012