W925EP01 Datasheet, PDF (37/108 Pages) Winbond – 8-BIT CID MICROCONTROLLER

W925EP01/ W925EP01FG
WTRF: Watchdog Timer Reset Flag. Hardware will set this bit when the watchdog timer causes a
reset. Software can read it but must clear it manually. A power-fail reset will also clear the bit.
This bit helps software in determining the cause of a reset. If EWT = 0, the watchdog timer will
have no effect on this bit.
EWT: Enable Watchdog timer Reset. Setting this bit will enable the Watchdog timer Reset function.
RWT: Reset Watchdog Timer. This bit helps in putting the watchdog timer into a known state. It also
helps in resetting the watchdog timer before a time-out occurs. Failing to set the EWT before
time-out will cause an interrupt, if EWDI (EIE.5) is set, and 512 clocks after that a watchdog
timer reset will be generated if EWT is set. This bit is self-clearing by hardware.
Note:
The WDCON SFR is set to a 0x000xx0b on an external reset. WTRF is set to a 1 on a Watchdog
timer reset, but to a 0 on power on/down resets. WTRF is not altered by an external reset. POR is set
to 1 by a power-on reset. EWT is set to 0 on a Power-on reset and unaffected by other resets.
ACCUMULATOR
(initial=00H)
Bit:
7
6
5
4
3
2
1
0
ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0
Mnemonic: ACC
Address: E0h
ACC.7-0: The ACC register.
ISP ADDRESS LOW BYTE
(INITIAL=00H)
Bit:
7
6
5
4
3
2
1
0
A7
A6
A5
A4
A3
A2
A1
A0
Mnemonic: SFRAL
Address: E4h
The low byte destination address is for In System Programming operations. The SFRAH and SFRAL
address register are specific ROM bytes for erasure, programming or read.
ISP ADDRESS HIGH BYTE
(INITIAL=00H)
Bit:
7
6
5
4
3
2
1
0
A15 A14 A13 A12 A11 A10 A9
A8
Mnemonic: SFRAH
Address: E5h
The high byte destination address is for In System Programming operations. The SFRAH and SFRAL
address are specific ROM bytes for erasure, programming or read.
ISP DATA BUFFER
(INITIAL=FFH)
Bit:
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
Mnemonic: SFRFD
Address: E6h
In ISP mode, read/write a specific byte ROM content must go through SFRFD register.
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Publication Release Date: Apr. 10, 2006
Revision A2