
Operating Modes and On-Chip Memory
Operating Modes
M68HC11K Family
Technical Data
MOTOROLA
Operating Modes and On-Chip Memory
79
For a detailed description of bootstrap mode, refer to the Motorola
application note entitled MC68HC11 Bootstrap Mode, document order
number AN1060/D.
4.5.4 Special Test Mode
Special test mode, a variation of the expanded mode, is used primarily
during Motorola’s internal production testing. However, for those devices
containing EPROM, it can be used to program the EPROM for program
calibration data in EEPROM and support emulation and debugging
during development.
4.5.5 Mode Selection
The operating mode is selected by applying the appropriate logic states
to the MODA and MODB pins during reset. MODA selects single-chip
mode (0) or expanded mode (1). A logic high on MODB selects normal
modes, and vectors are fetched from memory area $FFC0–$FFFF. A
logic low on MODB selects special modes, and reset vectors are fetched
from memory area $BFC0–$BFFF. Values reflecting the selected mode
are latched into the RBOOT, SMOD, and MDA bits of the highest priority
I-bit interrupt and miscellaneous register (HPRIO) on the rising edge of
RESET.
Table 4-2. Synchronization Character Selection
Synchronization
Character
Timeout
Delay
Baud Rate at E Clocks
2 MHz
3 MHz
4 MHz
$FF
4 characters
7812
11,718
15,624
$FF
4 characters
1200
1800
2400
$F0
9600
14,400
19,200
$FD
13 characters
3906
5859
7812
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