AT90S4414
have a single 16-bit word format. Every program memory
address contains a 16- or 32-bit instruction.
rupts are executed). The 16-bit stack pointer SP is
read/write accessible in the I/O space.
During interrupts and subroutine calls, the return address
program counter (PC) is stored on the stack. The stack is
effectively allocated in the general data SRAM, and conse-
quently the stack size is only limited by the total SRAM size
and the usage of the SRAM. All user programs must initial-
ize the SP in the reset routine (before subroutines or inter-
The 256 bytes data SRAM can be easily accessed through
the five different addressing modes supported in the AVR
architecture.
The memory spaces in the AVR architecture are all linear
and regular memory maps.
Figure 5. Memory Maps
A flexible interrupt module has its control registers in the
I/O space with an additional global interrupt enable bit in
the status register. All the different interrupts have a sepa-
rate interrupt vector in the interrupt vector table at the
beginning of the program memory. The different interrupts
have priority in accordance with their interrupt vector posi-
tion. The lower the interrupt vector address the higher prior-
ity.
5
ATMEL [ ATMEL ]
