W78LE516 Datasheet, PDF (14/31 Pages) Winbond – 8-BIT MICROCONTROLLER

Preliminary W78LE516
F04KBOOT Mode (Boot From LDROM)
By default, the W78LE516 boots from APROM program after a power on reset. On some occasions,
user can force the W78LE516 to boot from the LDROM program via following settings. The possible
situation that you need to enter F04KBOOT 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 F04KBOOT mode to force the W78LE516 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 W78LE516 to enter the F04KBOOT 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
F04KBOOT mode.
F04KBOOT MODE
P4.3
X
L
P2.7
L
X
P2.6
L
X
MODE
FO4KBOOT
FO4KBOOT
The Reset Timing For Entering
F04KBOOT Mode
P2.7
Hi-Z
P2.6
RST
30 mS
10 mS
Hi-Z
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