MC908QT4MPE datasheet(65/184 Pages) FREESCALE

65 / 184 page

Arithmetic/Logic Unit (ALU)

MC68HC908QY/QT Family Data Sheet, Rev. 5

Freescale Semiconductor

Z — Zero Flag

The CPU sets the zero flag when an arithmetic operation, logic operation, or data manipulation

produces a result of $00.

1 = Zero result

0 = Non-zero result

C — Carry/Borrow Flag

The CPU sets the carry/borrow flag when an addition operation produces a carry out of bit 7 of the

accumulator or when a subtraction operation requires a borrow. Some instructions — such as bit test

and branch, shift, and rotate — also clear or set the carry/borrow flag.

1 = Carry out of bit 7

0 = No carry out of bit 7

7.4 Arithmetic/Logic Unit (ALU)

The ALU performs the arithmetic and logic operations defined by the instruction set.

Refer to the CPU08 Reference Manual (document order number CPU08RM/AD) for a description of the

instructions and addressing modes and more detail about the architecture of the CPU.

7.5 Low-Power Modes

The WAIT and STOP instructions put the MCU in low power-consumption standby modes.

7.5.1 Wait Mode

The WAIT instruction:

•

Clears the interrupt mask (I bit) in the condition code register, enabling interrupts. After exit from

wait mode by interrupt, the I bit remains clear. After exit by reset, the I bit is set.

•

Disables the CPU clock

7.5.2 Stop Mode

The STOP instruction:

•

Clears the interrupt mask (I bit) in the condition code register, enabling external interrupts. After

exit from stop mode by external interrupt, the I bit remains clear. After exit by reset, the I bit is set.

•

Disables the CPU clock

After exiting stop mode, the CPU clock begins running after the oscillator stabilization delay.

7.6 CPU During Break Interrupts

If a break module is present on the MCU, the CPU starts a break interrupt by:

•

Loading the instruction register with the SWI instruction

•

Loading the program counter with $FFFC:$FFFD or with $FEFC:$FEFD in monitor mode

The break interrupt begins after completion of the CPU instruction in progress. If the break address

A return-from-interrupt instruction (RTI) in the break routine ends the break interrupt and returns the MCU

to normal operation if the break interrupt has been deasserted.

MC908QT4MPE Datasheet(PDF) 65 Page - Freescale Semiconductor, Inc

MC908QT4MPE Datasheet(HTML) 65 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL