SC51D01Fxx

program should always clear the WDT to avoid that WDT overflows. When the program enters dead loop, maybe

WDT is not clear in time. WDT will overflow to make MCU reset to avoid the system is in abnormal state for a

long time.

OSCILLATION CIRCUIT

oscillator, shown in Fig. 5. The waveform generated by the oscillation circuit produced the system clock MClk

which provides clock to S51 MCU and some periphery modules after it is shaped by the inverter.

Fig. 5 – Oscillation circuit

Where:

Rf is the feedback resistor, 1MΩ.

Rd is the dirve resistor , 300~600Ω

C1 and C2 are load capacitors, capacitance is the same and the range is 10pF~30pF.

XTAL is crystal oscillator, and the fixed frequency is 12MHz.

PERIPHERY MODULES

Keyboard Input Ports

[Brief]

SC51D01Fxx series has 8 input ports KI0~KI7 used to connect with the keyboard. Every port has pull-up

resistor and Schmitt trigger.

[Structure Diagram]

Figure 6 – Keyboard input structure

HANGZHOU MICROELECTRONICS CO.,LTD

REV:1.0

2007.12.03

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