Resets and Interrupts
Effects of Reset
MC68HC11E Family
—
Rev. 4
Technical Data
MOTOROLA
Resets and Interrupts
115
5.4.1 Central Processor Unit (CPU)
After reset, the central processor unit (CPU) fetches the restart vector
from the appropriate address during the first three cycles and begins
executing instructions. The stack pointer and other CPU registers are
indeterminate immediately after reset; however, the X and I interrupt
mask bits in the condition code register (CCR) are set to mask any
interrupt requests. Also, the S bit in the CCR is set to inhibit stop mode.
5.4.2 Memory Map
After reset, the INIT register is initialized to $01, mapping the RAM at $00
and the control registers at $1000.
For the MC68HC811E2, the CONFIG register resets to $FF. EEPROM
mapping bits (EE[3:0]) place the EEPROM at $F800. Refer to the
memory map diagram for MC68HC811E2 in
Section 4. Operating
Modes and On-Chip Memory
.
5.4.3 Timer
During reset, the timer system is initialized to a count of $0000. The
prescaler bits are cleared, and all output compare registers are initialized
to $FFFF. All input capture registers are indeterminate after reset. The
output compare 1 mask (OC1M) register is cleared so that successful
OC1 compares do not affect any I/O pins. The other four output
compares are configured so that they do not affect any I/O pins on
successful compares. All input capture edge-detector circuits are
configured for capture disabled operation. The timer overflow interrupt
flag and all eight timer function interrupt flags are cleared. All nine timer
interrupts are disabled because their mask bits have been cleared.
The I4/O5 bit in the PACTL register is cleared to configure the I4/O5
function as OC5; however, the OM5:OL5 control bits in the TCTL1
register are clear so OC5 does not control the PA3 pin.