
Resets and Interrupts
Effects of Reset
M68HC11E Family — Rev. 5
Data Sheet
MOTOROLA
Resets and Interrupts
95
5.3.6  Computer Operating Properly (COP) 
The COP watchdog system is enabled if the NOCOP control bit in the CONFIG 
register is cleared and disabled if NOCOP is set. The COP rate is set for the 
shortest duration timeout. 
5.3.7  Serial Communications Interface (SCI) 
The reset condition of the SCI system is independent of the operating mode. At 
reset, the SCI baud rate control register (BAUD) is initialized to $04. All transmit 
and receive interrupts are masked and both the transmitter and receiver are 
disabled so the port pins default to being general-purpose I/O lines. The SCI frame 
format is initialized to an 8-bit character size. The send break and receiver wakeup 
functions are disabled. The TDRE and TC status bits in the SCI status register 
(SCSR) are both 1s, indicating that there is no transmit data in either the transmit 
data register or the transmit serial shift register. The RDRF, IDLE, OR, NF, FE, PF, 
and RAF receive-related status bits in the SCI control register 2 (SCCR2) are 
cleared. 
5.3.8  Serial Peripheral Interface (SPI) 
The SPI system is disabled by reset. The port pins associated with this function 
default to being general-purpose I/O lines. 
5.3.9  Analog-to-Digital (A/D) Converter 
The analog-to-digital (A/D) converter configuration is indeterminate after reset. The 
ADPU bit is cleared by reset, which disables the A/D system. The conversion 
complete flag is indeterminate. 
5.3.10  System 
The EEPROM programming controls are disabled, so the memory system is 
configured for normal read operation. PSEL[3:0] are initialized with the value 
%0110, causing the external IRQ pin to have the highest I-bit interrupt priority. The 
IRQ pin is configured for level-sensitive operation (for wired-OR systems). The 
RBOOT, SMOD, and MDA bits in the HPRIO register reflect the status of the 
MODB and MODA inputs at the rising edge of reset. MODA and MODB inputs 
select one of the four operating modes. After reset, writing SMOD and MDA in 
special modes causes the MCU to change operating modes. Refer to the 
description of HPRIO register in 
Section 2. Operating Modes and On-Chip 
Memory
 for a detailed description of SMOD and MDA. The DLY control bit is set 
to specify that an oscillator startup delay is imposed upon recovery from stop 
mode. The clock monitor system is disabled because CME is cleared. 
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