MC68HC05F8 Datasheet, PDF (109/126 Pages) Motorola, Inc – High-density complementary metal oxide semiconductor(HCMOS) microcontroller unit

Freescale Semiconductor, Inc.
LAT - Latch EPROM Data and Address
1 (set) – EPROM address and data buses configured for programming.
0 (clear) – EPROM address and data buses configured for normal reads.
LAT causes address and data buses to be latched when a write to EPROM is carried out. The
EPROM cannot be read if LAT=1. This bit should not be set unless a programming voltage is
applied to the VPP pin.
EPGM - EPROM Programming Mode Enable
1 (set) – Programming power connected to the EPROM array.
0 (clear) – Programming power disconnected from the EPROM array.
LAT and EPMG cannot be set on the same write operation. EPMG can only be set if LAT is set.
EPMG is automatically cleared when LAT is cleared.
12.3.2 EPROM Programming Sequence
In the bootstrap, the user program contained in an external EPROM is copied into the internal
EPROM of the MC68HC705F8 device (see Figure 12-5). The MC68HC705F8 device is inserted
into the programming circuit as shown in Figure 12-5. Programming routine is selected via mode
switch S1, and +5V and VPP power is applied to the programming circuitry. The MCU is removed
from the reset state and placed in the run mode of operation via switch S4, and MCU control is
transferred to the bootstrap ROM. The selected programming routine is then executed.
Programming sequence of events are as follows:
1) Place switch S4 to RESET position (switch close).
2) Select programming routine via switches S1.
3) Apply +5 V and VPP power to programming circuitry.
4) Place switch S4 to RUN position (switch open).
5) Programming routine is executed.
6) Place switch S4 to RESET position.
7) Remove VPP and +5 V power, or select and run new routine.
Once the bootstrap mode is entered, mode switch setting is scanned to establish the routine to be
executed. The routines are:
– Program and Verify EPROM
– Verify EPROM Contents
12
Note:
When programming the window part MC68HC705F8, the window should be covered
up to prevent erratic device behaviour.
MC68HC05F8
OPERATING MODES
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TPG
MOTOROLA
12-5