mc68hc11f1cpu3 Freescale Semiconductor, Inc, mc68hc11f1cpu3 Datasheet - Page 45

• Manufacturer Part Number: mc68hc11f1cpu3
• Description: Mc68hc11f1 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

4.3.1 Mode Selection
TECHNICAL DATA
Notes:
1. Bits 1 and 0 can be written once only in first 64 cycles. When SMOD = 1, these bits can be written any time. All
2. Bits can be written to zero (protection disabled) once only in first 64 cycles or at any time in special modes. Bits
3. Bits 5, 4, 2, 1, and 0 can be written once only in first 64 cycles. When SMOD = 1, bits 5, 4, 2, 1, and 0 can be
4. Bit 5 (CLK4X) can be written only one time.
5. Bit 4 (IRV) can be written only one time.
6. Can be written once in first 64 cycles after reset in normal modes or at any time in special modes.
The four mode variations are selected by the logic levels present on the MODA and
MODB pins at the rising edge of RESET. The MODA and MODB logic levels determine
the logic state of SMOD and MDA control bits in the HPRIO register.
After reset is released, the mode select pins no longer influence the MCU operating
mode. In single-chip operating mode, the MODA pin is connected to a logic level zero.
In expanded mode, MODA should be connected to V
4.7 k . The MODA pin also functions as the load instruction register (LIR) pin when
the MCU is not in reset. The open-drain active low LIR output pin drives low during the
first E cycle of each instruction (opcode fetch). The MODB pin also functions as stand-
by power input (V
V
requirements.
Refer to Table 4-3, which is a summary of mode pin operation, the mode control bits,
and the four operating modes.
Register
Address
DD
other bits can be written at any time.
can be set to one at any time.
written at any time. All other bits can be written at any time
$x03C
$x03D
$x024
$x035
$x038
$x039
MODB
. Refer to APPENDIX A ELECTRICAL CHARACTERISTICS for V
1
1
0
0
Input Levels
at Reset
Timer Interrupt Mask 2 (TMSK2)
Block Protect Register (BPROT)
System Configuration Options 2 (OPT2)
System Configuration Options (OPTION)
Highest Priority I-bit and Miscellaneous (HPRIO)
RAM and I/O Map Register (INIT)
STBY
Table 4-3 Hardware Mode Select Summary
Table 4-2 Write Access Limited Registers
MODA
Freescale Semiconductor, Inc.
OPERATING MODES AND ON-CHIP MEMORY
0
1
0
1
For More Information On This Product,
), which allows RAM contents to be maintained in absence of
Register
Name
Go to: www.freescale.com
Special Bootstrap
Special Test
Single Chip
Expanded
Mode
Must be Written in
First 64 Cycles
RBOOT
DD
0
0
1
0
Note 1
Note 2
Note 3
through a pull-up resistor of
Yes
No
No
Control Bits in HPRIO
(Latched at Reset)
SMOD
0
0
1
1
Write One Time
STBY
Note 4
Note 5
Note 6
Only
—
—
—
MDA
voltage
0
1
0
1
4-7