ATXMEGA8E5_14 datasheet(10/147 Pages) ATMEL

10 / 147 page

XMEGA E5 [DATASHEET]

Atmel-8153I–AVR-ATxmega8E5-ATxmega16E5-ATxmega32E5_Datasheet–08/2014

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.

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.

7.8

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.

ATXMEGA8E5 Datasheet(PDF) 10 Page - ATMEL Corporation