W925EP01 Datasheet, PDF (68/108 Pages) Winbond – 8-BIT CID MICROCONTROLLER

W925EP01/ W925EP01FG
6.17 Hardware Writer Mode
1. H/W Writer Mode
This mode is for the writer to write / read Flash EPROM operation. A general user may not enter this
mode.
2. Enter Flash Writer Timing
Enter Flash Writer Mode Timing
P3.6
X
P3.7
X
P2.6
X
P2.7
X
/EA
X
/PSEN
X
RESET
Ts = 1us
Th =1us
6.18 In-System Programming (ISP) Mode
The W925EP01 equips one 64K byte of main Flash EPROM bank for application program (called
APROM) and one 4K byte of auxiliary Flash EPROM bank for loader program (called LDROM). In the
normal operation, the micro-controller executes the code in the APROM. If the content of APROM
needs to be modified, the W925EP01 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 AAH, and then 55H sequentially to the TA register to enable the CHPCON write
attribute. Writing TA register with the values except AAH and 55H will close CHPCON register
write attribute. The W925EP01 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
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