WinSystems PPC65-1210S, Product Manual

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110912 PRODUCT MANUAL PPC65 7
The related control registers of WDT are all included in the following sample program written in C language. Users can
fill in a non-zero value into the Time-Out Value Register to enable/refresh the WDT. The system will be reset after the
Time-Out Value to be counted down reaches zero, or the user can directly fill a zero value into Time-Out Value Register to
disable the WDT immediately. To ensure successful access to the content of the desired control register, the sequence of
the following program codes should be performed step-by-step when each register is accessed.
Additionally, a maximum of 2 seconds of counting tolerance should be considered into the user’s application program. For
more information about WDT, please refer to the Winbond W8627HG-AW data sheet.
There are two PNP I/O port addresses that can be used to configure WDT,
1) 0x2E: EFIR (Extended Function Index Register, for identifying CR index number)
2) 0x2F: EFDR (Extended Function Data Register, for accessing desired CR)
Below are some example codes, which demonstrate the use of WDT.
//Step1. Enter W83627HG configuration registers mode:
outportb(0x2E, 0x87);
outportb(0x2E, 0x87);
//* Step2. Pin89 to be WDTO
outportb(0x2E, 0x2b);
outportb(0x2E + 1, 0x04);
//* Step. Select logic device 8:
outportb(0x2E, 0x07);
outportb(0x2E + 1, 0x08);
//* Step4. Config WDT using second to be unit:
outportb(0x2E, 0xf5);
outportb(0x2E + 1, 0x00);
//* Step5. Set WDT time-out time:
outportb(0x2E, 0xf6);
outportb(0x2E + 1, time_out);
//* Step6. Exit configuration registers mode:
outportb(0x2E, 0xaa);