CENTRAL PROCESSOR UNIT
M68HC16 Z SERIES
4-4
USER’S MANUAL
4.2.5 Condition Code Register
The 16-bit condition code register is composed of two functional blocks. The eight
MSB, which correspond to the CCR on the M68HC11, contain the low-power stop con-
trol bit and processor status flags. The eight LSB contain the interrupt priority field, the
DSP saturation mode control bit, and the program counter address extension field.
shows the condition code register. Detailed descriptions of each status in-
dicator and field in the register follow the figure.
Figure 4-2 Condition Code Register
S — STOP Enable
0 = Stop clock when LPSTOP instruction is executed.
1 = Perform NOP when LPSTOP instruction is executed.
MV — Accumulator M overflow flag
MV is set when an overflow into AM35 has occurred.
H — Half Carry Flag
H is set when a carry from A3 or B3 occurs during BCD addition.
EV — Accumulator M Extension Overflow Flag
EV is set when an overflow into AM31 has occurred.
N — Negative Flag
N is set under the following conditions:
• When the MSB is set in the operand of a read operation.
• When the MSB is set in the result of a logic or arithmetic operation.
Z — Zero Flag
Z is set under the following conditions:
• When all bits are zero in the operand of a read operation.
• When all bits are zero in the result of a logic or arithmetic operation.
V — Overflow Flag
V is set when a two’s complement overflow occurs as the result of an operation.
C — Carry Flag
C is set when a carry or borrow occurs during an arithmetic operation. This flag is also
used during shift and rotate to facilitate multiple word operations.
IP[2:0] — Interrupt Priority Field
The priority value in this field (0 to 7) is used to mask interrupts.
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IP[2:0]
SM
PK[3:0]
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Freescale Semiconductor, Inc.
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