mc68hc711d3 Freescale Semiconductor, Inc, mc68hc711d3 Datasheet - Page 21

• Manufacturer Part Number: mc68hc711d3
• Description: M Hc11 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 2
Operating Modes and Memory
2.1 Introduction
This section contains information about:
2.2 Operating Modes
The MC68HC711D3 uses two dedicated pins, MODA and MODB, to select one of two normal operating
modes or one of two special operating modes. A value reflecting the microcontroller unit (MCU) status or
mode selected is latched on bits SMOD and MDA of the highest priority I-bit interrupt and miscellaneous
register (HPRIO) on the rising edge of reset. The normal operating modes are the single-chip and
expanded-multiplexed modes. The special operating modes are the bootstrap and test modes.
shows mode selection according to the values encoded on the MODA and MODB pins, and the value
latched in the SMOD and MDA bits.
2.2.1 Single-Chip Mode
In single-chip mode, the MCU functions as a self-contained microcontroller and has no external address
or data bus. The 4-Kbyte erasable programmable read-only memory (EPROM) would contain all program
code and is located at $F000–$FFFF. This mode provides maximum use of the pins for on-chip peripheral
functions, and all the address and data activity occurs within the MCU.
2.2.2 Expanded Multiplexed Mode
In the expanded-multiplexed mode, the MCU can address up to 64 Kbytes of address space. High-order
address bits are output on the port B pins. Low-order address bits and the bidirectional data bus are
multiplexed on port C. The AS pin provides the control output used in demultiplexing the low-order
address. The R/W pin is used to control the direction of data transfer on the port C bus.
Freescale Semiconductor
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The modes that define MC68HC711D3 operating conditions
The on-chip memory that allows the microcontroller unit (MCU) to be configured for various
applications
The 4-Kbytes of programmable read-only memory (PROM)
RESET
1
1
1
1
0
MODA
0
1
0
1
0
MODB
1
1
0
0
0
MC68HC711D3 Data Sheet, Rev. 2.1
Table 2-1. Mode Selection
Normal — single chip
Normal — expanded multiplexed
Special — bootstrap (BOOT)
Special — test
Reserved
Mode Selected
SMOD
X
0
0
1
1
MDA
X
0
1
0
1
Table 2-1
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