MC68HC05B6_13 Datasheet, PDF (105/302 Pages) Freescale Semiconductor, Inc – Microcontrollers

9
RESETS AND INTERRUPTS
9.1
Resets
The MC68HC05B6 can be reset in three ways: by the initial power-on reset function, by an active
low input to the RESET pin or by a computer operating properly (COP) watchdog reset. Any of
these resets will cause the program to go to its starting address, specified by the contents of
memory locations $1FFE and $1FFF, and cause the interrupt mask bit in the condition code
register to be set.
t_VDDR
V_DD
V_DD threshold (1-2V typical)
t_OXOV
OSC1
t_PORL
t_CYC
Internal
processor clock
RESET
Internal
address bus
Internal
data bus
(Internal power-on reset)
t_RL(or t_DOGL) _{(External hardware reset)}
1FFE 1FFE 1FFE 1FFE 1FFF
New
PC
Reset sequence
New New Op
PCH PCL code
Program
execution
begins
1FFE 1FFE 1FFE 1FFE
1FFF
New
PC
Reset sequence
New New Op
PCH PCL code
Program
execution
begins
9
Figure 9-1 Reset timing diagram
MC68HC05B6
Rev. 4.1
RESETS AND INTERRUPTS
Freescale
9-1