GMS81C1404/GMS81C1408
6
SEP. 2004 Ver 1.3
5. PIN FUNCTION
VDD: Supply voltage.
VSS: Circuit ground.
RESET: Reset the MCU.
XIN: Input to the inverting oscillator amplifier and input to
the internal main clock operating circuit.
XOUT: Output from the inverting oscillator amplifier.
RA0~RA7: RA is an 8-bit, CMOS, bidirectional I/O port.
RA pins can be used as outputs or inputs according to “1”
or “0” written the their Port Direction Register(RAIO).
In addition, RA serves the functions of the various special
features in Table 5-1 .
RB0~RB7: RB is a 8-bit, CMOS, bidirectional I/O port.
RB pins can be used as outputs or inputs according to “1”
or “0” written the their Port Direction Register(RBIO).
RB serves the functions of the various following special
features in Table 5-2
RC3~RC6: RC is a 4-bit, CMOS, bidirectional I/O port.
RC pins can be used as outputs or inputs according to “1”
or “0” written the their Port Direction Register(RCIO).
RC serves the functions of the serial interface following
special features in Table 5-3 .
RD0~RD2: RD is a 3-bit, CMOS, bidirectional I/O port.
RC pins can be used as outputs or inputs according to “1”
or “0” written the their Port Direction Register(RDIO).
RD serves the functions of the external interrupt following
special features in Table 5-4
Port pin
Alternate function
RA0
RA1
RA2
RA3
RA4
RA5
RA6
RA7
EC0 ( Event Counter Input Source )
AN1 ( Analog Input Port 1 )
AN2 ( Analog Input Port 2 )
AN3 ( Analog Input Port 3 )
AN4 ( Analog Input Port 4 )
AN5 ( Analog Input Port 5 )
AN6 ( Analog Input Port 6 )
AN7 ( Analog Input Port 7 )
Table 5-1 RA Port
Port pin
Alternate function
RB0
RB1
RB2
RB3
RB4
RB5
RB6
RB7
AN0 ( Analog Input Port 0 )
AVref ( External Analog Reference Pin )
BUZ ( Buzzer Driving Output Port )
INT0 ( External Interrupt Input Port 0 )
INT1 ( External Interrupt Input Port 1 )
PWM0 (PWM0 Output)
COMP0 (Timer1 Compare Output)
PWM1 (PWM1 Output)
COMP1 (Timer3 Compare Output)
EC1 (Event Counter Input Source)
TMR2OV (Timer2 Overflow Output)
Table 5-2 RB Port
Port pin
Alternate function
RC3
RC4
RC5
RC6
SRDYIN (SPI Ready Input)
SRDYOUT (SPI Ready Output)
SCKI (SPI CLK Input)
SCKO (SPI CLK Output)
SIN (SPI Serial Data Input)
SOUT (SPI Serial Data Output)
Table 5-3 RC Port
Port pin
Alternate function
RD0
RD1
RD2
INT2 (External Interrupt Input Port 2)
INT3 (External Interrupt Input Port 3)
Table 5-4 RD Port
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