MC68HC705E5 Datasheet, PDF (108/148 Pages) Freescale Semiconductor, Inc – General Release Specification

User EPROM
Freescale Semiconductor, Inc.
Three pins are used to select various bootloader functions: PB0, PB3,
and PB4. PB0 is normally a SYNC pin, which is used to synchronize the
MCU to an off-chip source driving EPROM data into the MCU. If an
external EPROM is used, this pin must be connected to VSS. PB4 and
PB3 are used to select a programming mode. Two other pins, PC2 and
PC3, are used to drive the PROG LED and the VERF LED, respectively.
The programming modes along with gate and drain stress are shown in
Table 13-1.
PB0
SYNC
SYNC
SYNC
0
1
Table 13-1. Bootloader Functions
PB4
PB3
1
1
1
0
0
0
0
1
0
1
Mode
Program/Verify
Verify Only
Factory Test
Factory Test
Factory Test
The bootloader uses an external 12-bit counter to address the memory
device containing the code to be copied. This counter requires a clock
and a reset function. The 12-bit counter can address up to 4 Kbytes of
memory, which means that a port pin has to be used to address the extra
memory space.
General Release Specification
User EPROM
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MC68HC705E5 — Rev. 1.0