MC68HC05X4 Datasheet, PDF (14/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Modes of Operation and Pin Descriptions
Single chip mode
This is the normal operating mode of the MC68HC05X4. In this mode the
device functions as a self-contained microcomputer with all on-board
peripherals, including the two 8-bit I/O ports available to the user.
NOTE:
For the MC68HC705X4 all vectors are fetched from EPROM (locations
$1FF0–$1FFF) in single chip mode; therefore, the EPROM must be
programmed (via the bootloader mode) before the device is powered up
in single chip mode. The mask option register is loaded from the EPROM
($1F00) on reset so that emulation of mask programmable features is
possible.
Single chip mode is entered on the rising edge of RESET if the voltage
level on the MDS/TCAP(VPP) pin is within the normal operating range.
Bootloader modes for the MC68HC05X4 and MC68HC705X4
The entry conditions for these modes are identical. The bootloader mode
on the MC68HC705X4 is therefore a direct replacement for that on the
MC68HC05X4.
Bootloader mode is entered on the rising edge of RESET if the
MDS/TCAP(VPP) pin is at 2 x V_DD, the PB7 pin is at logic zero and the
PB1 pin at logic one, as shown in Table 1.
NOTE:
In order to program the EPROM correctly on the MC68HC705X4 the
MDS/TCAP(VPP) pin must be at the appropriate voltage – see DC
electrical characteristics.
Bootloader Mode
for the
MC68HC05X4
This mode allows the user to use his own test routines for the device by
providing a simple ‘RAM load and execute’ routine in ROM.
To make use of this feature a circuit board should be constructed as
shown in Figure 1. It is then possible, by correctly configuring port pins
PA2 and PA3, to load a user program into RAM and then to run it. The
following sections explain the functions of this mode.
MC68HC05X4 Rev 1.0
14
Modes of Operation and Pin Descriptions
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2-modes
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