Atmel AVR XMEGA AU User Manual
This document contains complete and detailed description of all modules included in
the Atmel
family of low-power, high-performance, and peripheral-rich CMOS 8/16-bit microcontrollers based on the AVR enhanced RISC architecture. The available Atmel AVR
XMEGA AU modules described in this manual are:
•
Atmel AVR CPU
• Memories
• DMAC - Direct memory access controller
• Event system
• System clock and clock options
• Power management and sleep modes
• System control and reset
• Battery backup system
• WDT - Watchdog timer
• Interrupts and programmable multilevel interrupt controller
• PORT - I/O ports
• TC - 16-bit timer/counters
• AWeX - Advanced waveform extension
• Hi-Res - High resolution extension
• RTC - Real-time counter
• RTC32 - 32-bit real-time counter
• USB - Universial serial bus interface
• TWI - Two-wire serial interface
• SPI - Serial peripheral interface
• USART - Universal synchronous and asynchronous serial receiver and transmitter
• IRCOM - Infrared communication module
• AES and DES cryptographic engine
• CRC - Cyclic redundancy check
• EBI - External bus interface
• ADC - Analog-to-digital converter
• DAC - Digital-to-analog converter
• AC - Analog comparator
• IEEE 1149.1 JTAG interface
• PDI - Program and debug interface
• Memory programming
• Peripheral address map
• Register summary
• Interrupt vector summary
• Instruction set summary
®
AVR®XMEGA®AU microcontroller family. The Atmel AVR XMEGA AU is a
8-bit Atmel
XMEGA AU
Microcontroller
XMEGA AU
MANUAL
8331B- AVR-03/12
1. About the Manual
This document contains in-depth documentation of all peripherals and modules available for the
Atmel AVR XMEGA AU microcontroller family. All features are documented on a functional level
and described in a general sense. All peripherals and modules described in this manual may not
be present in all Atmel AVR XMEGA AU devices.
For all device-specific information such as characterization data, memory sizes, modules,
peripherals available and their absolute memory addresses, refer to the device datasheets.
When several instances of a peripheral exists in one device, each instance will have a unique
name. For example each port module (PORT) have unique name, such as PORTA, PORTB,etc.
Register and bit names are unique within one module instance.
For more details on applied use and code examples for peripherals and modules, refer to the
Atmel AVR XMEGA specific application notes available from http://www.atmel.com/avr.
1.1 Reading the Manual
The main sections describe the various modules and peripherals. Each section contains a short
feature list and overview describing the module. The remaining section describes the features
and functions in more detail.
Atmel AVR XMEGA AU
The register description sections list all registers and describe each register, bit and flag with
their function. This includes details on how to set up and enable various features in the module.
When multiple bits are needed for a configuration setting, these are grouped together in a bit
group. The possible bit group configurations are listed for all bit groups together with their associated Group Configuration and a short description. The Group Configuration refers to the
defined configuration name used in the Atmel AVR XMEGA assembler header files and application note source code.
The register summary sections list the internal register map for each module type.
The interrupt vector summary sections list the interrupt vectors and offset address for each module type.
1.2 Resources
A comprehensive set of development tools, application notes, and datasheets are available for
download from http://www.atmel.com/avr.
1.3 Recommended Reading
• Atmel AVR XMEGA AU device datasheets
• XMEGA application notes
This manual contains general modules and peripheral descriptions. The AVR XMEGA AU device
datasheets contains the device-specific information. The XMEGA application notes and AVR
Software Framework contain example code and show applied use of the modules and peripherals.
8331B–AVR–03/12
For new users, it is recommended to read the AVR1000 - Getting Started Writing C Code for
Atmel XMEGA, and AVR1900 - Getting Started with Atmel ATxmega128A1 application notes.
2
2. Overview
Atmel AVR XMEGA AU
The AVR XMEGA AU microcontrollers is a family of low-power, high-performance, and peripheral-rich CMOS 8/16-bit microcontrollers based on the AVR enhanced RISC architecture. By
executing powerful instructions in a single clock cycle, the Atmel AVR XMEGA AU devices
achieve throughputs approaching one million instructions per second (MIPS) per megahertz,
allowing the system designer to optimize power consumption versus processing speed.
The AVR CPU combines a rich instruction set with 32 general purpose working registers. All 32
registers are directly connected to the arithmetic logic unit (ALU), allowing two independent registers to be accessed in a single instruction, executed in one clock cycle. The resulting
architecture is more code efficient while achieving throughputs many times faster than conventional single-accumulator or CISC based microcontrollers.
The Atmel AVR XMEGA AU devices provide the following features: in-system programmable
flash with read-while-write capabilities; internal EEPROM and SRAM; four-channel DMA controller; eight-channel event system and programmable multilevel interrupt controller; up to 78
general purpose I/O lines; 16- or 32-bit real-time counter (RTC); up to eight flexible, 16-bit
timer/counters with capture, compare and PWM modes; up to eight USARTs; up to four I
SMBUS compatible two-wire serial interfaces (TWIs); one full-speed USB 2.0 interface; up to
four serial peripheral interfaces (SPIs); CRC module; AES and DES cryptographic engine; up to
two 16-channel, 12-bit ADCs with programmable gain; up to two 2-channel, 12-bit DACs; up to
four analog comparators with window mode; programmable watchdog timer with separate internal oscillator; accurate internal oscillators with PLL and prescaler; and programmable brown-out
detection.
2
C and
The program and debug interface (PDI), a fast, two-pin interface for programming and debugging, is available. Selected devices also have an IEEE std. 1149.1 compliant JTAG interface,
and this can also be used for on-chip debug and programming.
The Atmel AVR XMEGA devices have five software selectable power saving modes. The idle
mode stops the CPU while allowing the SRAM, DMA controller, event system, interrupt controller, and all peripherals to continue functioning. The power-down mode saves the SRAM and
register contents, but stops the oscillators, disabling all other functions until the next TWI, USB
resume, or pin-change interrupt, or reset. In power-save mode, the asynchronous real-time
counter continues to run, allowing the application to maintain a timer base while the rest of the
device is sleeping. In standby mode, the external crystal oscillator keeps running while the rest
of the device is sleeping. This allows very fast startup from the external crystal, combined with
low power consumption. In extended standby mode, both the main oscillator and the asynchronous timer continue to run. To further reduce power consumption, the peripheral clock to each
individual peripheral can optionally be stopped in active mode and idle sleep mode.
The devices are manufactured using Atmel high-density, nonvolatile memory technology. The
program flash memory can be reprogrammed in-system through the PDI or JTAG interfaces. A
boot loader running in the device can use any interface to download the application program to
the flash memory. The boot loader software in the boot flash section will continue to run while
the application flash section is updated, providing true read-while-write operation. By combining
an 8/16-bit RISC CPU with In-system, self-programmable flash, the Atmel AVR XMEGA is a
powerful microcontroller family that provides a highly flexible and cost effective solution for many
embedded applications.
8331B–AVR–03/12
3
The Atmel AVR XMEGA AU devices are supported with a full suite of program and system
V
BAT
Power
Supervision
Battery Backup
Controller
Real Time
Counter
32.768 kHz
XOSC
Power
Supervision
POR/BOD &
RESET
PORT A (8)
PORT B (8)
EVENT ROUTING NETWORK
DMA
Controller
BUS
Matrix
SRAM
EBI
ADCA
DACA
ACA
DACB
ADCB
ACB
OCD
PORT K (8)
PORT J (8)
PORT H (8)
PDI
Watchdog
Timer
Watchdog
Oscillator
Interrupt
Controller
DATA BUS
Prog/Debug
Controller
PORT R (2)
Oscillator
Circuits/
Clock
Generation
Oscillator
Control
Real Time
Counter
Event System
Controller
JTAG
Sleep
Controller
DES
CRC
IRCOM
PORT G (8)
PORT L (8)
PORT Q (8)
PORT M (8)
PORT C (8)
TCC0:1
USARTC0:1
TWIC
SPIC
PORT D (8)
TCD0:1
USARTD0:1
TWID
SPID
TCF0:1
USARTF0:1
TWIF
SPIF
TCE0:1
USARTE0:1
TWIE
SPIE
PORT E (8) PORT F (8)
USB
EVENT ROUTING NETWORK
AES
AREFA
AREFB
PORT N (8)
PORT P (8)
CPU
NVM Controller
MORPEEhsalF
DATA BUS
Int. Refs.
Tempref
Digital function
Analog function
Bus masters / Programming / Debug
Oscillator / Crystal / Clock
General Purpose I/O
EBI
development tools, including C compilers, macro assemblers, program debugger/simulators,
programmers, and evaluation kits.Block Diagram
Figure 2-1. Atmel AVR XMEGA AU block diagram.
Atmel AVR XMEGA AU
8331B–AVR–03/12
4
Atmel AVR XMEGA AU
In Table 2-1 on page 5 a feature summary for the XMEGA AU family is shown, split into one feature summary column for each sub-family. Each sub-family has identical feature set, but different
memory options, refer to their device datasheet for ordering codes and memory options.
Table 2-1. XMEGA AU feature summary overview.
Feature Details / sub-family A1U A3U A3BU A4U
Pins, I/O
Memory
Package
QTouch Sense channels 56 56 56 56
DMA Controller Channels 4 4 4 4
Event System
Crystal Oscillator
To t al 100 64 64 44
Programmable I/O pins 78 50 47 34
Program memory (KB) 64 - 128 64 - 256 256 16 - 128
Boot memory (KB) 4 - 8 4 - 8 8 4 - 8
SRAM (KB) 4 - 8 4 - 16 16 2 - 8
EEPROM 2 2 - 4 4 1 -2
General purpose registers 16 16 16 16
TQFP 100A 64A 64A 44A
QFN /VQFN – 64M2 64M2 44M1
BGA 100C1/100C2 – – 49C2
Channels 8 8 8 8
QDEC 3 3 3 3
0.4 - 16MHz XOSC Yes Ye s Yes Ye s
32.768 kHz TOSC Yes Yes Ye s Yes
2MHz calibrated Yes Ye s Yes Ye s
32MHz calibrated Yes Ye s Yes Ye s
Internal Oscillator
Timer / Counter
Battery Backup System Yes
8331B–AVR–03/12
128MHz PLL Yes Ye s Yes Ye s
32.768kHz calibrated Yes Yes Yes Ye s
32kHz ULP Yes Yes Yes Yes
TC0 - 16-bit, 4 CC 4 4 4 3
TC1 - 16-bit, 2 CC 4 3 2 2
TC2 - 2x 8-bit 4 4 4 2
Hi-Res 4 4 4 3
AWeX 4 2 2 1
RTC 1 1 1
RTC32 1
5
Atmel AVR XMEGA AU
Feature Details / sub-family A1U A3U A3BU A4U
USB full-speed device 1 1 1 1
Serial Communication
Crypto /CRC
External Memory (EBI)
Analog to Digital
Converter (ADC)
USART 8 7 6 5
SPI 4 3 3 2
TWI 4 2 2 2
AES-128 Yes Ye s Yes Ye s
DES Yes Ye s Yes Ye s
CRC-16 Ye s Yes Ye s Yes
CRC-32 Ye s Yes Ye s Yes
Chip selects 4 – – –
SRAM Yes
SDRAM Ye s
2 2 2 1
Resolution (bits) 12 12 12 12
Sampling speed (kbps) 2000 2000 2000 2000
Input channels per ADC 16 16 16 12
Conversion channels 4 4 4 4
2 1 1 1
Digital to Analog
Converter (DAC)
Analog Comparator (AC) 4 4 4 2
Program and Debug
Interface
Resolution (bits) 12 12 12 12
Sampling speed (kbps) 1000 1000 1000 1000
Output channels per DAC 2 2 2 2
PDI Yes Ye s Yes Ye s
JTAG Ye s Yes Yes
Boundary scan Yes Ye s Yes
8331B–AVR–03/12
6
3. AVR CPU
3.1 Features
3.2 Overview
Atmel AVR XMEGA AU
• 8/16-bit, high-performance Atmel AVR RISC CPU
– 142 instructions
– Hardware multiplier
• 32x8-bit registers directly connected to the ALU
• Stack in RAM
• Stack pointer accessible in I/O memory space
• Direct addressing of up to 16MB of program memory and 16MB of data memory
• True 16/24-bit access to 16/24-bit I/O registers
• Efficient support for 8-, 16-, and 32-bit arithmetic
• Configuration change protection of system-critical features
All Atmel AVR XMEGA devices use the 8/16-bit AVR CPU. The main function of the CPU is to
execute the code and perform all calculations. The CPU is able to access memories, perform
calculations, control peripherals, and execute the program in the flash memory. Interrupt handling is described in a separate section, ”Interrupts and Programmable Multilevel Interrupt
Controller” on page 134.
3.3 Architectural Overview
In order to maximize performance and parallelism, the AVR CPU uses a Harvard architecture
with separate memories and buses for program and data. Instructions in the program memory
are executed with single-level pipelining. While one instruction is being executed, the next
instruction is pre-fetched from the program memory. This enables instructions to be executed on
every clock cycle. For a summary of all AVR instructions, refer to ”Instruction Set Summary” on
page 456. For details of all AVR instructions, refer to http://www.atmel.com/avr.
Figure 3-1. Block diagram of the AVR CPU architecture.
8331B–AVR–03/12
7
Atmel AVR XMEGA AU
The arithmetic logic unit (ALU) supports arithmetic and logic operations between registers or
between a constant and a register. Single-register operations can also be executed in the ALU.
After an arithmetic operation, the status register is updated to reflect information about the result
of the operation.
The ALU is directly connected to the fast-access register file. The 32 x 8-bit general purpose
working registers all have single clock cycle access time allowing single-cycle arithmetic logic
unit operation between registers or between a register and an immediate. Six of the 32 registers
can be used as three 16-bit address pointers for program and data space addressing, enabling
efficient address calculations.
The memory spaces are linear. The data memory space and the program memory space are
two different memory spaces.
The data memory space is divided into I/O registers, SRAM, and external RAM. In addition, the
EEPROM can be memory mapped in the data memory.
All I/O status and control registers reside in the lowest 4KB addresses of the data memory. This
is referred to as the I/O memory space. The lowest 64 addresses can be accessed directly, or as
the data space locations from 0x00 to 0x3F. The rest is the extended I/O memory space, ranging
from 0x0040 to 0x0FFF. I/O registers here must be accessed as data space locations using load
(LD/LDS/LDD) and store (ST/STS/STD) instructions.
The SRAM holds data. Code execution from SRAM is not supported. It can easily be accessed
through the five different addressing modes supported in the AVR architecture. The first SRAM
address is 0x2000.
Data addresses 0x1000 to 0x1FFF are reserved for memory mapping of EEPROM.
The program memory is divided in two sections, the application program section and the boot
program section. Both sections have dedicated lock bits for write and read/write protection. The
SPM instruction that is used for self-programming of the application flash memory must reside in
the boot program section. The application section contains an application table section with separate lock bits for write and read/write protection. The application table section can be used
forsave storing of nonvolatile data in the program memory.
3.4 ALU - Arithmetic Logic Unit
The arithmetic logic unit supports arithmetic and logic operations between registers or between
a constant and a register. Single-register operations can also be executed. The ALU operates in
direct connection with all 32 general purpose registers. In a single clock cycle, arithmetic operations between general purpose registers or between a register and an immediate are executed
and the result is stored in the register file. After an arithmetic or logic operation, the status register is updated to reflect information about the result of the operation.
ALU operations are divided into three main categories – arithmetic, logical, and bit functions.
Both 8- and 16-bit arithmetic is supported, and the instruction set allows for efficient implementation of 32-bit aritmetic. The hardware multiplier supports signed and unsigned multiplication and
fractional format.
8331B–AVR–03/12
8
3.4.1 Hardware Multiplier
The multiplier is capable of multiplying two 8-bit numbers into a 16-bit result. The hardware multiplier supports different variations of signed and unsigned integer and fractional numbers:
• Multiplication of unsigned integers
• Multiplication of signed integers
• Multiplication of a signed integer with an unsigned integer
• Multiplication of unsigned fractional numbers
• Multiplication of signed fractional numbers
• Multiplication of a signed fractional number with an unsigned one
A multiplication takes two CPU clock cycles.
3.5 Program Flow
After reset, the CPU starts to execute instructions from the lowest address in the flash programmemory ‘0.’ The program counter (PC) addresses the next instruction to be fetched.
Program flow is provided by conditional and unconditional jump and call instructions capable of
addressing the whole address space directly. Most AVR instructions use a 16-bit word format,
while a limited number use a 32-bit format.
Atmel AVR XMEGA AU
During interrupts and subroutine calls, the return address PC is stored on the stack. The stack is
allocated in the general data SRAM, and consequently the stack size is only limited by the total
SRAM size and the usage of the SRAM. After reset, the stack pointer (SP) points to the highest
address in the internal SRAM. The SP is read/write accessible in the I/O memory space,
enabling easy implementation of multiple stacks or stack areas. The data SRAM can easily be
accessed through the five different addressing modes supported in the AVR CPU.
3.6 Instruction Execution Timing
The AVR CPU is clocked by the CPU clock, clk
on page 9 shows the parallel instruction fetches and instruction executions enabled by the Har-
vard architecture and the fast-access register file concept. This is the basic pipelining concept
used to obtain up to 1MIPS/MHz performance with high power efficiency.
Figure 3-2. The parallel instruction fetches and instruction executions.
1st Instruction Fetch
1st Instruction Execute
2nd Instruction Fetch
2nd Instruction Execute
3rd Instruction Fetch
clk
CPU
. No internal clock division is used. Figure 3-2
CPU
T1 T2 T3 T4
8331B–AVR–03/12
3rd Instruction Execute
4th Instruction Fetch
9
Atmel AVR XMEGA AU
Total Execution Time
Register Operands Fetch
ALU Operation Execute
Result Write Back
T1 T2 T3 T4
clk
CPU
Figure 3-3 on page 10 shows the internal timing concept for the register file. In a single clock
cycle, an ALU operation using two register operands is executed and the result is stored back to
the destination register.
Figure 3-3. Single Cycle ALU Operation
3.7 Status Register
The status register (SREG) contains information about the result of the most recently executed
arithmetic or logic instruction. This information can be used for altering program flow in order to
perform conditional operations. Note that the status register is updated after all ALU operations,
as specified in the instruction set reference. This will in many cases remove the need for using
the dedicated compare instructions, resulting in faster and more compact code.
The status register is not automatically stored when entering an interrupt routine nor restored
when returning from an interrupt. This must be handled by software.
The status register is accessible in the I/O memory space.
3.8 Stack and Stack Pointer
The stack is used for storing return addresses after interrupts and subroutine calls. It can also be
used for storing temporary data. The stack pointer (SP) register always points to the top of the
stack. It is implemented as two 8-bit registers that are accessible in the I/O memory space. Data
are pushed and popped from the stack using the PUSH and POP instructions. The stack grows
from a higher memory location to a lower memory location. This implies that pushing data onto
the stack decreases the SP, and popping data off the stack increases the SP. The SP is automatically loaded after reset, and the initial value is the highest address of the internal SRAM. If
the SP is changed, it must be set to point above address 0x2000, and it must be defined before
any subroutine calls are executed or before interrupts are enabled.
During interrupts or subroutine calls, the return address is automatically pushed on the stack.
The return address can be two or three bytes, depending on program memory size of the device.
For devices with 128KB or less of program memory, the return address is two bytes, and hence
the stack pointer is decremented/incremented by two. For devices with more than 128KB of program memory, the return address is three bytes, and hence the SP is decremented/incremented
by three. The return address is popped off the stack when returning from interrupts using the
RETI instruction, and from subroutine calls using the RET instruction.
8331B–AVR–03/12
10
3.9 Register File
Atmel AVR XMEGA AU
The SP is decremented by one when data are pushed on the stack with the PUSH instruction,
and incremented by one when data is popped off the stack using the POP instruction.
To prevent corruption when updating the stack pointer from software, a write to SPL will automatically disable interrupts for up to four instructions or until the next I/O memory write.
The register file consists of 32 x 8-bit general purpose working registers with single clock cycle
access time. The register file supports the following input/output schemes:
• One 8-bit output operand and one 8-bit result input
• Two 8-bit output operands and one 8-bit result input
• Two 8-bit output operands and one 16-bit result input
• One 16-bit output operand and one 16-bit result input
Six of the 32 registers can be used as three 16-bit address register pointers for data space
addressing, enabling efficient address calculations. One of these address pointers can also be
used as an address pointer for lookup tables in flash program memory.
Figure 3-4. AVR CPU general purpose working registers.
The register file is located in a separate address space, and so the registers are not accessible
as data memory.
3.9.1 The X-, Y-, and Z- Registers
Registers R26..R31 have added functions besides their general-purpose usage.
7 0 Addr.
R0 0x00
R1 0x01
R2 0x02
…
R13 0x0D
General R14 0x0E
Purpose R15 0x0F
Working R16 0x10
Registers R17 0x11
…
R26 0x1A X-register Low Byte
R27 0x1B X-register High Byte
R28 0x1C Y-register Low Byte
R29 0x1D Y-register High Byte
R30 0x1E Z-register Low Byte
R31 0x1F Z-register High Byte
8331B–AVR–03/12
These registers can form 16-bit address pointers for addressing data memory. These three
address registers are called the X-register, Y-register, and Z-register. The Z-register can also be
used as an address pointer to read from and/or write to the flash program memory, signature
rows, fuses, and lock bits.
11
Figure 3-5. The X-, Y- and Z-registers.
Bit (individually) 7 R27 07 R26 0
X-register
Bit (X-register) 15 8 7 0
Bit (individually) 7 R29 07 R28 0
Y-register
Bit (Y-register) 15 8 7 0
Bit (individually) 7 R31 07 R30 0
Z-register
Bit (Z-register) 15 8 7 0
The lowest register address holds the least-significant byte (LSB), and the highest register
address holds the most-significant byte (MSB). In the different addressing modes, these address
registers function as fixed displacement, automatic increment, and automatic decrement (see
the instruction set reference for details).
3.10 RAMP and Extended Indirect Registers
In order to access program memory or data memory above 64KB, the address pointer must be
larger than 16 bits. This is done by concatenating one register to one of the X-, Y-, or Z-registers.
This register then holds the most-significant byte (MSB) in a 24-bit address or address pointer.
Atmel AVR XMEGA AU
XH XL
YH YL
ZH ZL
These registers are available only on devices with external bus interface and/or more than 64KB
of program or data memory space. For these devices, only the number of bits required to
address the whole program and data memory space in the device is implemented in the
registers.
3.10.1 RAMPX, RAMPY and RAMPZ Registers
The RAMPX, RAMPY and RAMPZ registers are concatenated with the X-, Y-, and Z-registers,
respectively, to enable indirect addressing of the whole data memory space above 64KB and up
to 16MB.
Figure 3-6. The combined RAMPX + X, RAMPY + Y and RAMPZ + Z registers.
Bit (Individually) 7 0 7 0 7 0
Bit (X-pointer) 23 16 15 8 7 0
Bit (Individually) 7 0 7 0 7 0
Bit (Y-pointer) 23 16 15 8 7 0
Bit (Individually) 7 0 7 0 7 0
Bit (Z-pointer) 23 16 15 8 7 0
When reading (ELPM) and writing (SPM) program memory locations above the first 128KB of
the program memory, RAMPZ is concatenated with the Z-register to form the 24-bit address.
LPM is not affected by the RAMPZ setting.
RAMPX XH XL
RAMPY YH YL
RAMPZ ZH ZL
8331B–AVR–03/12
12
3.10.2 RAMPD Register
This register is concatenated with the operand to enable direct addressing of the whole data
memory space above 64KB. Together, RAMPD and the operand will form a 24-bit address.
Figure 3-7. The combined RAMPD + K register.
Bit (Individually) 7 0 15 0
Bit (D-pointer) 23 16 15 0
3.10.3 EIND - Extended Indirect Register
EIND is concatenated with the Z-register to enable indirect jump and call to locations above the
first 128KB (64K words) of the program memory.
Figure 3-8. The combined EIND + Z register.
Bit (Individually) 7 0 7 0 7 0
Bit (D-pointer) 23 16 15 8 7 0
3.11 Accessing 16-bit Registers
The AVR data bus is 8 bits wide, and so accessing 16-bit registers requires atomic operations.
These registers must be byte-accessed using two read or write operations. 16-bit registers are
connected to the 8-bit bus and a temporary register using a 16-bit bus.
Atmel AVR XMEGA AU
RAMPD K
EIND ZH ZL
For a write operation, the low byte of the 16-bit register must be written before the high byte. The
low byte is then written into the temporary register. When the high byte of the 16-bit register is
written, the temporary register is copied into the low byte of the 16-bit register in the same clock
cycle.
For a read operation, the low byte of the 16-bit register must be read before the high byte. When
the low byte register is read by the CPU, the high byte of the 16-bit register is copied into the
temporary register in the same clock cycle as the low byte is read. When the high byte is read, it
is then read from the temporary register.
This ensures that the low and high bytes of 16-bit registers are always accessed simultaneously
when reading or writing the register.
Interrupts can corrupt the timed sequence if an interrupt is triggered and accesses the same 16bit register during an atomic 16-bit read/write operation. To prevent this, interrupts can be disabled when writing or reading 16-bit registers.
The temporary registers can also be read and written directly from user software.
3.11.1 Accessing 24- and 32-bit Registers
For 24- and 32-bit registers, the read and write access is done in the same way as described for
16-bit registers, except there are two temporary registers for 24-bit registers and three for 32-bit
registers. The least-significant byte must be written first when doing a write, and read first when
doing a read.
3.12 Configuration Change Protection
System critical I/O register settings are protected from accidental modification. The SPM instruction is protected from accidental execution, and the LPM instruction is protected when reading
8331B–AVR–03/12
13
the fuses and signature row. This is handled globally by the configuration change protection
(CCP) register. Changes to the protected I/O registers or bits, or execution of protected instructions, are only possible after the CPU writes a signature to the CCP register. The different
signatures are described in the register description.
There are two modes of operation: one for protected I/O registers, and one for the protected
instructions, SPM/LPM.
3.12.1 Sequence for write operation to protected I/O registers
1. The application code writes the signature that enable change of protected I/O registers
to the CCP register.
2. Within four instruction cycles, the application code must write the appropriate data to
the protected register. Most protected registers also contain a write enable/change
enable bit. This bit must be written to one in the same operation as the data are written.
The protected change is immediately disabled if the CPU performs write operations to
the I/O register or data memory or if the SPM, LPM, or SLEEP instruction is executed.
3.12.2 Sequence for execution of protected SPM/LPM
1. The application code writes the signature for the execution of protected SPM/LPM to
the CCP register.
2. Within four instruction cycles, the application code must execute the appropriate
instruction. The protected change is immediately disabled if the CPU performs write
operations to the data memory or if the SLEEP instruction is executed.
Once the correct signature is written by the CPU, interrupts will be ignored for the duration of the
configuration change enable period. Any interrupt request (including non-maskable interrupts)
during the CCP period will set the corresponding interrupt flag as normal, and the request is kept
pending. After the CCP period is completed, any pending interrupts are executed according to
their level and priority. DMA requests are still handled, but do not influence the protected configuration change enable period. A signature written by DMA is ignored.
Atmel AVR XMEGA AU
3.13 Fuse Lock
8331B–AVR–03/12
For some system-critical features, it is possible to program a fuse to disable all changes to the
associated I/O control registers. If this is done, it will not be possible to change the registers from
the user software, and the fuse can only be reprogrammed using an external programmer.
Details on this are described in the datasheet module where this feature is available.
14
3.14 Register Descriptions
3.14.1 CCP – Configuration Change Protection register
Bit 76543210
+0x04 CCP[7:0] CCP
Read/WriteWWWWWWR/WR/W
Initial Value 00000000
• Bit 7:0 – CCP[7:0]: Configuration Change Protection
The CCP register must be written with the correct signature to enable change of the protected
I/O register or execution of the protected instruction for a maximum period of four CPU instruction cycles. All interrupts are ignored during these cycles. After these cycles, interrupts will
automatically be handled again by the CPU, and any pending interrupts will be executed according to their level and priority. When the protected I/O register signature is written, CCP[0] will
read as one as long as the protected feature is enabled. Similarly when the protected SPM/LPM
signature is written, CCP[1] will read as one as long as the protected feature is enabled.
CCP[7:2] will always read as zero. Table 3-1 on page 15 shows the signature for the various
modes.
Atmel AVR XMEGA AU
Table 3-1. Modes of CPU change protection.
Signature Group Configuration Description
0x9D SPM Protected SPM/LPM
0xD8 IOREG Protected IO register
3.14.2 RAMPD – Extended Direct Addressing register
This register is concatenated with the operand for direct addressing (LDS/STS) of the whole
data memory space on devices with more than 64KB of data memory. This register is not available if the data memory, including external memory, is less than 64KB.
Bit 76543210
+0x08 RAMPD[7:0] RAMPD
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
• Bit 7:0 – RAMPD[7:0]: Extended Direct Addressing bits
These bits hold the MSB of the 24-bit address created by RAMPD and the 16-bit operand. Only
the number of bits required to address the available data memory is implemented for each
device. Unused bits will always read as zero.
3.14.3 RAMPX – Extended X-Pointer register
This register is concatenated with the X-register for indirect addressing (LD/LDD/ST/STD) of the
whole data memory space on devices with more than 64KB of data memory. This register is not
available if the data memory, including external memory, is less than 64KB.
8331B–AVR–03/12
15
Bit 76543210
+0x09 RAMPX[7:0] RAMPX
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 00000000
• Bit 7:0 – RAMPX[7:0]: Extended X-pointer Address bits
These bits hold the MSB of the 24-bit address created by RAMPX and the 16-bit X-register. Only
the number of bits required to address the available data memory is implemented for each
device. Unused bits will always read as zero.
3.14.4 RAMPY – Extended Y-Pointer register
This register is concatenated with the Y-register for indirect addressing (LD/LDD/ST/STD) of the
whole data memory space on devices with more than 64KB of data memory. This register is not
available if the data memory, including external memory, is less than 64KB.
Bit 76543210
+0x0A RAMPY[7:0] RAMPY
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 00000000
Atmel AVR XMEGA AU
• Bit 7:0 – RAMPY[7:0]: Extended Y-pointer Address bits
These bits hold the MSB of the 24-bit address created by RAMPY and the 16-bit Y-register. Only
the number of bits required to address the available data memory is implemented for each
device. Unused bits will always read as zero.
3.14.5 RAMPZ – Extended Z-Pointer register
This register is concatenated with the Z-register for indirect addressing (LD/LDD/ST/STD) of the
whole data memory space on devices with more than 64KB of data memory. RAMPZ is concatenated with the Z-register when reading (ELPM) program memory locations above the first 64KB
and writing (SPM) program memory locations above the first 128KB of the program memory.
This register is not available if the data memory, including external memory and program memory in the device, is less than 64KB.
Bit 76543210
+0x0B RAMPZ[7:0] RAMPZ
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 00000000
• Bit 7:0 – RAMPZ[7:0]: Extended Z-pointer Address bits
These bits hold the MSB of the 24-bit address created by RAMPZ and the 16-bit Z-register. Only
the number of bits required to address the available data and program memory is implemented
for each device. Unused bits will always read as zero.
3.14.6 EIND – Extended Indirect register
This register is concatenated with the Z-register for enabling extended indirect jump (EIJMP)
and call (EICALL) to the whole program memory space on devices with more than 128KB of program memory. The register should be used for jumps to addresses below 128KB if
8331B–AVR–03/12
16
ECALL/EIJMP are used, and it will not be used if CALL and IJMP commands are used. For jump
or call to addresses below 128KB, this register is not used. This register is not available if the
program memory in the device is less than 128KB.
Bit 76543210
+0x0C EIND[7:0] EIND
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 00000000
• Bit 7:0 – EIND[7:0]: Extended Indirect Address bits
These bits hold the MSB of the 24-bit address created by EIND and the 16-bit Z-register. Only
the number of bits required to access the available program memory is implemented for each
device. Unused bits will always read as zero.
3.14.7 SPL – Stack Pointer Register Low
The SPH and SPL register pair represent the 16-bit SP value. The SP holds the stack pointer
that points to the top of the stack. After reset, the stack pointer points to the highest internal
SRAM address. To prevent corruption when updating the stack pointer from software, a write to
SPL will automatically disable interrupts for the next four instructions or until the next I/O memory write.
Atmel AVR XMEGA AU
Only the number of bits required to address the available data memory, including external memory, up to 64KB is implemented for each device. Unused bits will always read as zero.
Bit 76543210
+0x0D SP[7:0] SPL
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value
(1)
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
Note: 1. Refer to specific device datasheets for exact initial values.
• Bit 7:0 – SP[7:0]: Stack Pointer Register Low
These bits hold the LSB of the 16-bit stack pointer (SP).
3.14.8 SPH – Stack Pointer Register High
Bit 76543210
+0x0E SP[15:8] SPH
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value
(1)
0/10/10/10/10/10/10/10/1
Note: 1. Refer to specific device datasheets for exact initial values.
• Bit 7:0 – SP[15:8]: Stack Pointer Register High
These bits hold the MSB of the 16-bit stack pointer (SP).
8331B–AVR–03/12
17
3.14.9 SREG – Status Register
The status register (SREG) contains information about the result of the most recently executed
arithmetic or logic instruction.
Bit 76543210
+0x0F I T H S V N Z C SREG
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 00000000
• Bit 7 – I: Global Interrupt Enable
The global interrupt enable bit must be set for interrupts to be enabled. If the global interrupt
enable register is cleared, none of the interrupts are enabled independent of the individual interrupt enable settings. This bit is not cleared by hardware after an interrupt has occurred. This bit
can be set and cleared by the application with the SEI and CLI instructions, as described in
“Instruction Set Description.” Changing the I flag through the I/O-register result in a one-cycle
wait state on the access.
• Bit 6 – T: Bit Copy Storage
The bit copy instructions bit load (BLD) and bit store (BST) use the T bit as source or destination
for the operated bit. A bit from a register in the register file can be copied into this bit by the BST
instruction, and this bit can be copied into a bit in a register in the register file by the BLD
instruction.
Atmel AVR XMEGA AU
• Bit 5 – H: Half Carry Flag
The half carry flag (H) indicates a half carry in some arithmetic operations. Half carry Is useful in
BCD arithmetic. See “Instruction Set Description” for detailed information.
• Bit 4 – S: Sign Bit, S = N
⊕ V
The sign bit is always an exclusive or between the negative flag, N, and the two’s complement
overflow flag, V. See “Instruction Set Description” for detailed information.
• Bit 3 – V: Two’s Complement Overflow Flag
The two’s complement overflow flag (V) supports two’s complement arithmetic. See “Instruction
Set Description” for detailed information.
• Bit 2 – N: Negative Flag
The negative flag (N) indicates a negative result in an arithmetic or logic operation. See “Instruction Set Description” for detailed information.
• Bit 1 – Z: Zero Flag
The zero flag (Z) indicates a zero result in an arithmetic or logic operation. See “Instruction Set
Description” for detailed information.
• Bit 0 – C: Carry Flag
The carry flag (C) indicates a carry in an arithmetic or logic operation. See “Instruction Set
Description” for detailed information.
8331B–AVR–03/12
18
Atmel AVR XMEGA AU
3.15 Register Summary
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Page
+0x00 Reserved – – – – – – – –
+0x01 Reserved – – – – – – – –
+0x02 Reserved
+0x03 Reserved
+0x04 CCP CCP[7:0] 15
+0x05 Reserved – – – – – – – –
+0x06 Reserved – – – – – – – –
+0x07 Reserved – – – – – – – –
+0x08 RAMPD RAMPD[7:0] 15
+0x09 RAMPX RAMPX[7:0] 15
+0x0A RAMPY RAMPY[7:0] 16
+0x0B RAMPZ RAMPZ[7:0] 16
+0x0C EIND EIND[7:0] 16
+0x0D SPL SPL[7:0] 17
+0x0E SPH SPH[7:0] 17
+0x0F SREG I T H S V N Z C 18
– – – – – – – –
– – – – – – – –
8331B–AVR–03/12
19
4. Memories
4.1 Features
Atmel AVR XMEGA AU
• Flash program memory
– One linear address space
– In-system programmable
– Self-programming and boot loader support
– Application section for application code
– Application table section for application code or data storage
– Boot section for application code or bootloader code
– Separate read/write protection lock bits for all sections
– Built in fast CRC check of a selectable flash program memory section
• Data memory
– One linear address space
– Single-cycle access from CPU
– SRAM
– EEPROM
Byte and page accessible
Optional memory mapping for direct load and store
– I/O memory
Configuration and status registers for all peripherals and modules
16 bit-accessible general purpose registers for global variables or flags
– External memory support
SRAM
SDRAM
Memory mapped external hardware
– Bus arbitration
Deterministic handling of priority between CPU, DMA controller, and other bus masters
– Separate buses for SRAM, EEPROM, I/O memory, and external memory access
Simultaneous bus access for CPU and DMA controller
• Production signature row memory for factory programmed data
– ID for each microcontroller device type
– Serial number for each device
– Calibration bytes for factory calibrated peripherals
• User signature row
– One flash page in size
– Can be read and written from software
– Content is kept after chip erase
4.2 Overview
8331B–AVR–03/12
This section describes the different memory sections. The AVR architecture has two main memory spaces, the program memory and the data memory. Executable code can reside only in the
program memory, while data can be stored in the program memory and the data memory. The
data memory includes the internal SRAM, and EEPROM for nonvolatile data storage. All memory spaces are linear and require no memory bank switching. Nonvolatile memory (NVM)
spaces can be locked for further write and read/write operations. This prevents unrestricted
access to the application software.
20
A separate memory section contains the fuse bytes. These are used for configuring important
Application Flash
Section
0x000000
End Application
Start Boot Loader
Flashend
Application Table
Flash Section
Boot Loader Flash
Section
system functions, and can only be written by an external programmer.
4.3 Flash Program Memory
All XMEGA devices contain on-chip in-system reprogrammable flash memory for program storage. The flash memory can be accessed for read and write from an external programmer
through the PDI or from application software running in the device.
All AVR CPU instructions are 16 or 32 bit wide, and each flash location is 16 bits wide. The flash
memory is organized in two main sections, the application section and the boot loader section,
as shown in Figure 4-1 on page 21. The sizes of the different sections are fixed, but devicedependent. These two sections have separate lock bits, and can have different levels of protection. The store program memory (SPM) instruction, used to write to the flash from the application
software, will only operate when executed from the boot loader section.
The application section contains an application table section with separate lock settings. This
enables safe storage of nonvolatile data in the program memory.
Figure 4-1. Flash memory sections.
Atmel AVR XMEGA AU
4.3.1 Application Section
4.3.2 Application Table Section
8331B–AVR–03/12
The Application section is the section of the flash that is used for storing the executable application code. The protection level for the application section can be selected by the boot lock bits
for this section. The application section can not store any boot loader code since the SPM
instruction cannot be executed from the application section.
The application table section is a part of the application section of the flash memory that can be
used for storing data. The size is identical to the boot loader section. The protection level for the
21
application table section can be selected by the boot lock bits for this section. The possibilities
for different protection levels on the application section and the application table section enable
safe parameter storage in the program memory. If this section is not used for data, application
code can reside here.
4.3.3 Boot Loader Section
While the application section is used for storing the application code, the boot loader software
must be located in the boot loader section because the SPM instruction can initiate programming when executing from this section. The SPM instruction can access the entire flash,
including the boot loader section itself. The protection level for the boot loader section can be
selected by the boot loader lock bits. If this section is not used for boot loader software, application code can be stored here.
4.3.4 Production Signature Row
The production signature row is a separate memory section for factory programmed data. It contains calibration data for functions such as oscillators and analog modules. Some of the
calibration values will be automatically loaded to the corresponding module or peripheral unit
during reset. Other values must be loaded from the signature row and written to the corresponding peripheral registers from software. For details on calibration conditions such as temperature,
voltage references, etc. refer to device datasheet.
Atmel AVR XMEGA AU
The production signature row also contains an ID that identifies each microcontroller device type
and a serial number for each manufactured device. The serial number consists of the production
lot number, wafer number, and wafer coordinates for the device.
The production signature row cannot be written or erased, but it can be read from application
software and external programmers.
4.3.5 User Signature Row
The user signature row is a separate memory section that is fully accessible (read and write)
from application software and external programmers. It is one flash page in size, and is meant
for static user parameter storage, such as calibration data, custom serial number, identification
numbers, random number seeds, etc. This section is not erased by chip erase commands that
erase the flash, and requires a dedicated erase command. This ensures parameter storage during multiple program/erase operations and on-chip debug sessions.
4.4 Fuses and Lockbits
The fuses are used to configure important system functions, and can only be written from an
external programmer. The application software can read the fuses. The fuses are used to configure reset sources such as brownout detector and watchdog, startup configuration, JTAG enable,
and JTAG user ID.
The lock bits are used to set protection levels for the different flash sections (i.e., if read and/or
write access should be blocked). Lock bits can be written by external programmers and application software, but only to stricter protection levels. Chip erase is the only way to erase the lock
bits. To ensure that flash contents are protected even during chip erase, the lock bits are erased
after the rest of the flash memory has been erased.
8331B–AVR–03/12
An unprogrammed fuse or lock bit will have the value one, while a programmed fuse or lock bit
will have the value zero.
Both fuses and lock bits are reprogrammable like the flash program memory.
22
4.5 Data Memory
I/O Memory
(Up to 4 KB)
EEPROM
(Up to 4 KB)
Internal SRAM
External Memory
(0 to 16 MB)
0x000000
0x001000
0xFFFFFF
0x002000
Start/End
Address
Data Memory
Atmel AVR XMEGA AU
The data memory contains the I/O memory, internal SRAM, optionally memory mapped
EEPROM, and external memory, if available. The data memory is organized as one continuous
memory section, as shown in Figure 4-2 on page 23.
Figure 4-2. Data memory map.
4.6 Internal SRAM
4.7 EEPROM
8331B–AVR–03/12
I/O memory, EEPROM, and SRAM will always have the same start addresses for all XMEGA
devices. The address space for external memory will always start at the end of internal SRAM
and end at address 0xFFFFFF.
The internal SRAM always starts at hexadecimal address 0x2000. SRAM is accessed by the
CPU using the load (LD/LDS/LDD) and store (ST/STS/STD) instructions.
All XMEGA devices have EEPROM for nonvolatile data storage. It is 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.
23
4.8 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 0x3F directly. In the address range 0x00 0x1F, single-cycle instructions for manipulation and checking of individual bits are available.
4.8.1 General Purpose I/O Registers
The lowest 16 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.
4.9 External Memory
Up to four ports are dedicated to external memory, supporting external SRAM, SDRAM, and
memory mapped peripherals such as LCD displays. For details, refer to ”EBI – External Bus
Interface” on page 335. The external memory address space will always start at the end of inter-
nal SRAM.
Atmel AVR XMEGA AU
4.10 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. See Figure 4-3 on page 24. The USB module acts as a bus master
and is connected directly to internal SRAM through a pseudo-dualport (PDP) interface.
Figure 4-3. Bus access.
CH0
CH1
CH2 CH3
Flash CRC
EEPROM
Non-Volatile
Memory
CPUDMA
OCD
Bus matrix
NVM
Controller
AC
ADC
DAC
Battery
Backup
Interrupt
Controller
Power
Management
Event System
Controller
Oscillator
Control
I/O
Crypto
modules
USB
USART
SPI
TWI
Timer /
Counter
Real Time
Counter
Peripherals and system modules
External
Programming
PDIAVR core
EBI
External
Memory
SRAM
RAM
8331B–AVR–03/12
24
4.10.1 Bus Priority
4.11 Memory Timing
Atmel AVR XMEGA AU
When several masters request access to the same bus, the bus priority is in the following order
(from higher to lower priority):
1. Bus Master with ongoing access.
2. Bus Master with ongoing burst.
a. Alternating DMA controller read and DMA controller write when they access the
same data memory section.
3. Bus Master requesting burst access.
a. CPU has priority.
4. Bus Master requesting bus access.
a. CPU has priority.
Read and write access to the I/O memory takes one CPU clock cycle. A write to SRAM takes
one cycle, and 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. External memory has multi-cycle
read and write. The number of cycles depends on the type of memory and configuration of the
external bus interface. Refer to the instruction summary for more details on instructions and
instruction timing.
4.12 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.
4.13 JTAG Disable
It is possible to disable the JTAG interface from the application software. This will prevent all
external JTAG access to the device until the next device reset or until JTAG is enabled again
from the application software. As long as JTAG is disabled, the I/O pins required for JTAG can
be used as normal I/O pins.
4.14 I/O Memory Protection
Some features in the device are regarded as critical for safety in some applications. Due to this,
it is possible to lock the I/O register related to the clock system, the event system and the
advanced waveform extensions. As long as the lock is enabled, all related I/O registers are
locked and they can not be written from the application software. The lock registers themselves
are protected by the configuration change protection mechanism. For details refer to ”Configura-
tion Change Protection” on page 13.
8331B–AVR–03/12
25
4.15 Register Description – NVM Controller
4.15.1 ADDR0 – Address register 0
The ADDR0, ADDR1, and ADDR2 registers represent the 24-bit value ADDR. This is used for
addressing all NVM sections for read, write, and CRC operations.
Bit 76543210
+0x00 ADDR[7:0] ADDR0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 1 1 1 1 1 1 1 1
• Bit 7:0 – ADDR[7:0]: Address Register Byte 0
This register gives the address low byte when accessing NVM locations.
4.15.2 ADDR1 – Address register 1
Bit 76543210
+0x01 ADDR[15:8] ADDR1
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Atmel AVR XMEGA AU
• Bit 7:0 – ADDR[15:8]: Address Register Byte 1
This register gives the address high byte when accessing NVM locations.
4.15.3 ADDR2 – Address register 2
Bit 76543210
+0x02 ADDR[23:16] ADDR2
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
• Bit 7:0 – ADDR[23:16]: Address Register Byte 2
This register gives the address extended byte when accessing NVM locations.
4.15.4 DATA0 – Data register 0
The DATA0, DATA1, and DATA registers represent the 24-bit value DATA. This holds data during NVM read, write, and CRC access.
Bit 76543210
+0x04 DATA[7:0] DATA0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
8331B–AVR–03/12
• Bit 7:0 – DATA[7:0]: Data Register Byte 0
This register gives the data value byte 0 when accessing NVM locations.
26
4.15.5 DATA1 – Data register 1
Bit 76543210
+0x05 DATA[15:8] DATA1
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
• Bit 7:0 – DATA[15:8]: Data Register Byte 1
This register gives the data value byte 1 when accessing NVM locations.
4.15.6 DATA2 – Data register 2
Bit 76543210
+0x06 DATA[23:16] DATA2
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
• Bit 7:0 – DATA[23:16]: Data Register 2
This register gives the data value byte 2 when accessing NVM locations.
Atmel AVR XMEGA AU
4.15.7 CMD – Command Register
Bit 76543210
+0x0A – CMD[6:0] CMD
Read/Write R R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
• Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write
this bit to zero when this register is written.
• Bit 6:0 – CMD[6:0]: Command
These bits define the programming commands for the flash. Bit 6 is only set for external programming commands. See ”Memory Programming” on page 431” for programming commands.
4.15.8 CTRLA – Control register A
Bit 76543210
+0x0B – – – – – – –CMDEXCTRLA
Read/Write RRRRRRRS
Initial Value 0 0 0 0 0 0 0 0
8331B–AVR–03/12
• Bit 7:1 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
27
• Bit 0 – CMDEX: Command Execute
Setting this bit will execute the command in the CMD register. This bit is protected by the configuration change protection (CCP) mechanism. Refer to ”Configuration Change Protection” on
page 13 for details on the CCP.
4.15.9 CTRLB – Control register B
Bit 7 6 5 4 3 2 1 0
+0x0C – – – – EEMAPEN FPRM EPRM SPMLOCK CTRLB
Read/Write R R R R R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
• Bit 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
• Bit 3 – EEMAPEN: EEPROM Data Memory Mapping Enable
Setting this bit enables data memory mapping of the EEPROM section. The EEPROM can then
be accessed using load and store instructions.
Atmel AVR XMEGA AU
• Bit 2 – FPRM: Flash Power Reduction Mode
Setting this bit enables power saving for the flash memory. If code is running from the application section, the boot loader section will be turned off, and vice versa. If access to the section
that is turned off is required, the CPU will be halted for a time equal to the start-up time from the
idle sleep mode.
• Bit 1 – EPRM: EEPROM Power Reduction Mode
Setting this bit enables power saving for the EEPROM. The EEPROM will then be turned off in a
manner equal to entering sleep mode. If access is required, the bus master will be halted for a
time equal the start-up time from idle sleep mode.
• Bit 0 – SPMLOCK: SPM Locked
This bit can be written to prevent all further self-programming. The bit is cleared at reset, and
cannot be cleared from software. This bit is protected by the configuration change protection
(CCP) mechanism. Refer to ”Configuration Change Protection” on page 13 for details on the
CCP.
4.15.10 INTCTRL – Interrupt Control register
Bit 76543210
+0x0D – – – – SPMLVL[1:0] EELVL[1:0] INTCTRL
Read/Write R R R R R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
8331B–AVR–03/12
• Bit 7:4 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
28
• Bit 3:2 – SPMLVL[1:0]: SPM Ready Interrupt Level
These bits enable the interrupt and select the interrupt level, as described in ”Interrupts and Pro-
grammable Multilevel Interrupt Controller” on page 134. This is a level interrupt that will be
triggered only when the NVMBUSY flag in the STATUS register is set to zero. Thus, the interrupt
should not be enabled before triggering an NVM command, as the NVMBUSY flag will not be set
before the NVM command is triggered. The interrupt should be disabled in the interrupt handler.
• Bit 1:0 – EELVL[1:0]: EEPROM Ready Interrupt Level
These bits enable the EEPROM ready interrupt and select the interrupt level, as described in
”Interrupts and Programmable Multilevel Interrupt Controller” on page 134. This is a level inter-
rupt that will be triggered only when the NVMBUSY flag in the STATUS register is set to zero.
Thus, the interrupt should not be enabled before triggering an NVM command, as the NVMBUSY flag will not be set before the NVM command is triggered. The interrupt should be
disabled in the interrupt handler.
4.15.11 STATUS – Status register
Bit 7 6 5432 1 0
+0x04 NVMBUSY FBUSY – – – – EELOAD FLOAD STATUS
Read/Write R R RRRR R R
Initial Value 0 0 0000 0 0
Atmel AVR XMEGA AU
• Bit 7 – NVMBUSY: Nonvolatile Memory Busy
The NVMBUSY flag indicates if the NVM (Flash, EEPROM, lockbit) is being programmed. Once
an operation is started, this flag is set and remains set until the operation is completed. The
NVMBUSY flag is automatically cleared when the operation is finished.
• Bit 6 – FBUSY: Flash Busy
The FBUSY flag indicates if a flash programming operation is initiated. Once an operation is
started the FBUSY flag is set and the application section cannot be accessed. The FBUSY flag
is automatically cleared when the operation is finished.
• Bit 5:2 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
• Bit 1 – EELOAD: EEPROM Page Buffer Active Loading
The EELOAD flag indicates that the temporary EEPROM page buffer has been loaded with one
or more data bytes. It remains set until an EEPROM page write or a page buffer flush operation
is executed. For more details see ”Flash and EEPROM Programming Sequences” on page 434.
• Bit 0 – FLOAD: Flash Page Buffer Active Loading
The FLOAD flag indicates that the temporary flash page buffer has been loaded with one or
more data bytes. It remains set until an application page write, boot page write, or page buffer
flush operation is executed. For more details see ”Flash and EEPROM Programming
Sequences” on page 434.
8331B–AVR–03/12
29
4.15.12 LOCKBITS – Lock Bit register
Bit 76543210
+0x07 BLBB[1:0] BLBA[1:0] BLBAT[1:0] LB[1:0] LOCKBITS
Read/Write RRRRRRRR
Initial Value 1 1 1 1 1 1 1 1
This register is a mapping of the NVM lock bits into the I/O memory space, which enable direct
read access from the application software. Refer to ”LOCKBITS – Lock Bit register” on page 35
for description.
Atmel AVR XMEGA AU
8331B–AVR–03/12
30
Loading...