W78E365 Datasheet, PDF (21/40 Pages) Winbond – 8-BIT MICROCONTROLLER

W78E365
6.11 H/W Reboot Mode (Boot from LDROM)
By default, the W78E365 boots from APROM program after a power on reset. On some occasions,
user can force the W78E365 to boot from the LDROM program via following settings. The possible
situation that you need to enter H/W REBOOT mode when the APROM program can not run properly
and device can not jump back to LDROM to execute in-system programming function. Then you can
use this H/W REBOOT mode to force the W78E365 jumps to LDROM and executes in-system
programming procedure. When you design your system, you may reserve the pins P2.6, P2.7 to
switches or jumpers. For example in a CD-ROM system, you can connect the P2.6 and P2.7 to PLAY
and EJECT buttons on the panel. When the APROM program fails to execute the normal application
program. User can press both two buttons at the same time and then turn on the power of the
personal computer to force the W78E365 to enter the H/W REBOOT mode. After power on of
personal computer, you can release both buttons and finish the in-system programming procedure to
update the APROM code. In application system design, user must take care of the P2, P3, ALE, EA
and PSEN pin value at reset to prevent from accidentally activating the programming mode or H/W
REBOOT mode. It is necessary to add 10K resistor on these P2.6, P2.7 and P4.3 pins.
H/W Reboot Mode
P4.3 P2.7 P2.6
X
L
L
L
X
X
MODE
REBOOT
REBOOT
The Reset Timing For Entering
F04KBOOT Mode
P2.7
Hi-Z
P2.6
RST
30 mS
10 mS
Hi-Z
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Publication Release Date: April 20, 2005
Revision A5