mc68hc705j2 Freescale Semiconductor, Inc, mc68hc705j2 Datasheet - Page 47

• Manufacturer Part Number: mc68hc705j2
• Description: 8-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

5.1 Resets
5.1.1 Power-On Reset
MC68HC705J2
This section describes how resets reinitialize the MCU and how interrupts
temporarily change the normal processing sequence.
A reset immediately stops the operation of the instruction being executed. A
reset initializes certain control bits to known conditions and loads the program
counter with a user-defined reset vector address.
produce a reset:
A reset does the following things to reinitialize the MCU:
A positive transition on the V
reset is strictly for power-up conditions and cannot be used to detect drops in
power supply voltage.
• Initial power-up (power-on reset)
• A logical zero applied to the RESET pin (external reset)
• Timeout of the COP timer (COP reset)
• An opcode fetch from an address not in the memory map (illegal address
• Clears all implemented data direction register bits so that the
• Loads the stack pointer with $FF
• Sets the interrupt mask, inhibiting interrupts
• Clears the TOFE and RTIE bits in the timer control and status register
• Clears the STOP latch, enabling the CPU clocks
• Clears the WAIT latch, waking the CPU from the WAIT mode
• Loads the program counter with the user-defined reset vector
reset)
corresponding I/O pins are inputs
RESETS AND INTERRUPTS
RESETS AND INTERRUPTS
DD
SECTION 5
pin generates a power-on reset. The power-on
The following conditions
MOTOROLA
5-1