w78le58 Winbond Electronics Corp America, w78le58 Datasheet - Page 11

• Manufacturer Part Number: w78le58
• Description: 8-bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

In-System Programming (ISP) Mode
The W78LE58 equips one 32K byte of main MTP-ROM bank for application program (called APROM)
and one 4K byte of auxiliary MTP-ROM bank for loader program (called LDROM). In the normal
operation, the microcontroller executes the code in the APROM. If the content of APROM needs to be
modified, the W78LE58 allows user to activate the In-System Programming (ISP) mode by setting the
CHPCON register. The CHPCON is read-only by default, software must write two specific
values 87H, then 59H sequentially to the CHPENR register to enable the CHPCON write
attribute. Writing CHPENR register with the values except 87H and 59H will close CHPCON
register write attribute. The W78LE58 achieves all in-system programming operations including
enter/exit ISP Mode, program, erase, read ... etc, during device in the idle mode. Setting the bit
CHPCON.0 the device will enter in-system programming mode after a wake-up from idle mode.
Because device needs proper time to complete the ISP operations before awaken from idle mode,
software may use timer interrupt to control the duration for device wake-up from idle mode. To
perform ISP operation for revising contents of APROM, software located at APROM setting the
CHPCON register then enter idle mode, after awaken from idle mode the device executes the
corresponding interrupt service routine in LDROM. Because the device will clear the program counter
while switching from APROM to LDROM, the first execution of RETI instruction in interrupt service
routine will jump to 00H at LDROM area. The device offers a software reset for switching back to
APROM while the content of APROM has been updated completely. Setting CHPCON register bit 0,
1 and 7 to logic-1 will result a software reset to reset the CPU. The software reset serves as a
external reset. This in-system programming feature makes the job easy and efficient in which the
application needs to update firmware frequently. In some applications, the in-system programming
feature make it possible to easily update the system firmware without opening the chassis.
Note: The ISP Mode operates by supply voltage from 3.3V to 5.5V.
REGISTER
P4xAL
P4xAH
ADDRESS BUS
WRITE
READ
P4 REGISTER
P4.x
REGISTER
P4xCMP0
P4xCMP1
EQUAL
Bit Length
Selectable
comparator
P4xCSINV
- 11 -
P4xFUN0
P4xFUN1
P4.x INPUT DATA BUS
Preliminary W78LE58
DATA I/O
RD/WR_CS
WR_CS
RD_CS
MUX 4->1
Publication Release Date: June 2000
P4.x
PIN
Revision A1