
M68HC11
REFERENCE MANUAL
CONFIGURATION AND MODES OF OPERATION
MOTOROLA
3-13
While OCCR is set to one, the internal 8-Kbyte ROM is disabled,
regardless of the states of the ROMON bit in the CONFIG register or
the TCON bit in the TEST1 register.
0 = Function disabled; port A operates as in normal modes.
CBYP — Timer Divider Chain Bypass
Can be written only while SMOD equals one
1 = The 16-bit free-running timer is divided into 8-bit halves, and the prescaler is
bypassed. The E clock directly drives both halves of the timer. This function
greatly reduces testing time for the main timer system.
0 = Timer system operates normally.
DISR — Disable Resets from COP and Clock Monitor
Can be written only while SMOD equals one; forced to zero if SMOD equals zero
1 = Regardless of other control bit states, the COP and clock monitor systems do
not generate a system reset. This function assures that testing operations are
not interrupted by the COP or clock monitor protection mechanisms.
0 = COP and clock monitor resets operate normally.
NOTE
Users of the special bootstrap mode often forget that this bit is reset
to a one in the bootstrap mode. If a bootloaded program uses one of
these reset functions, this bit must be explicitly cleared by the loaded
program. This is probably the only test-related control bit that is of
interest to the user.
FCM — Force Clock Monitor Failure
Can be written only while SMOD equals one
1 = Writing a logic one to this location generates an immediate clock monitor failure
reset if the clock monitor enable (CME) bit in the OPTION register is also set.
0 = System operates normally.
The DISR control bit has priority over this bit and inhibits the forced reset functions.
FCOP — Force COP Watchdog Time-Out
Can be written only while SMOD equals one
1 = Writing a logic one to this location generates an immediate COP failure reset if
either the NOCOP bit in the CONFIG register is zero or the TCON bit in the
TEST1 register is one.
0 = System operates normally.
The DISR control bit has priority over this bit and inhibits the forced reset functions.
TCON — Test Configuration
Can be written only while SMOD equals one
1 = Overrides the specifications in the CONFIG register so that COP is enabled
and ROM and EEPROM are in the memory map. If the OCCR bit is set to one,
ROM is removed from the memory map, regardless of other control bits.
0 = Configuration options are controlled by the CONFIG register.