W79E825A/824A/823B/822B Data Sheet
5
PIN DESCRIPTION
SYMBOL
TYPE DESCRIPTIONS
RESET: A low on this pin for two machine cycles while the oscillator is
running resets the device.
I
RST (P1.5)
CRYSTAL1: This is the crystal oscillator input. This pin may be driven by
an external clock or configurable I/O pin.
XTAL1(P2.1)
I/O
I/O
CRYSTAL2: This is the crystal oscillator output. It is the inversion of
XTAL1 or configurable I/O pin.
XTAL2(P2.0)
VSS
VDD
P
P
GROUND: Ground potential
POWER: SUPPLY: Supply voltage for operation.
PORT 0: Port 0 is four mode output pin and two mode input. The
P0.3~P0.6 are 4-channel input ports (ADC0-ADC3) for ADC used.
I/O
I/O
P0.0−P0.7
P1.0−P1.7
PORT 1: Port 1 is four mode output pin and two mode input. The P1.2
(SCL) and P1.3 (SDA) is only open drain circuit, and P1.5 only input pin.
* TYPE: P: power, I: input, O: output, I/O: bi-directional, H: pull-high, L: pull-low, D: open-drain.
Table 5-1: Pin Description
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