Rainbow-electronics ATtiny26L Bedienungsanleitung PDF herunterladen (Seite 19)

ATtiny26(L)

1477B–AVR–04/02

• Bit 2 – N: Negative Flag

The Negative Flag N indicates a negative result after the different arithmetic and logic

operations. See the Instruction Set Description for detailed information.

• Bit 1 – Z: Zero Flag

The Zero Flag Z indicates a zero result after the different arithmetic and logic opera-

tions. See the 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 the Instruction

Set Description for detailed information.

Stack Pointer – SP The ATtiny26/L Stack Pointer is implemented as an 8-bit register in the I/O space loca-

tion $3D ($5D). As the ATtiny26/L data memory has 224 ($E0) locations, eight bits are

used.

The Stack Pointer points to the data SRAM stack area where the Subroutine and Inter-

rupt Stacks are located. This Stack space in the data SRAM must be defined by the

program before any subroutine calls are executed or interrupts are enabled. The Stack

Pointer must be set to point above $60. The Stack Pointer is decremented by one when

data is pushed onto the Stack with the PUSH instruction, and it is decremented by two

when an address is pushed onto the Stack with subroutine calls and interrupts. The

Stack Pointer is incremented by one when data is popped from the Stack with the POP

instruction, and it is incremented by two when an address is popped from the Stack with

return from subroutine RET or return from interrupt RETI.

Bit 76543210

$3D ($5D) SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0 SP

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value00000000

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Rainbow-electronics ATtiny26L Bedienungsanleitung Seite 19