W78E516B-24 Winbond, W78E516B-24 Datasheet - Page 9

• Manufacturer Part Number: W78E516B-24
• Description: 8-BIT MICROCONTROLLER
• Manufacturer: Winbond

CHPCON (BFH), continued
F04KBOOT Mode (Boot From LDROM)
By default, the W78E516B boots from APROM program after a power on reset. On some occasions,
user can force the W78E516B to boot from the LDROM program via following
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 W78E516B 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 W78E516B 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
F04KBOOT mode.
F04KBOOT MODE
PSEN pin value at reset to prevent from accidentally activating the programming mode or
P4.3
BIT
X
L
0
P2.7
FPROGEN MTP-ROM Programming Enable.
X
L
NAME
P2.6
X
L
= 1: enable. The microcontroller enter the in-system programming mode after
= 0: disable. The on-chip flash memory is read-only. In-system
FO4KBOOT
FO4KBOOT
entering the idle mode and wake-up from interrupt. During in-system
programming mode, the operation of erase, program and read are
achieve when device enters idle mode.
programmability is disabled.
P2.7
P2.6
RST
MODE
The Reset Timing For Entering
F04KBOOT Mode
30 mS
- 9 -
10 mS
FUNCTION
Hi-Z
Hi-Z
Publication Release Date: February 2000
settings.
W78E516B
The possible
Revision A3