PIC16F631_08 Datasheet, PDF (68/306 Pages) Microchip Technology – 20-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology

PIC16F631/677/685/687/689/690
4.2.5.4 RA3/MCLR/VPP
Figure 4-4 shows the diagram for this pin. The
RA3/MCLR/VPP pin is configurable to function as one
of the following:
• a general purpose input
• as Master Clear Reset with weak pull-up
FIGURE 4-4:
BLOCK DIAGRAM OF RA3
VDD
MCLRE
Weak
Data Bus
Reset
RD
VSS
TRISA
RD
PORTA
DQ
WR
IOCA
CK _Q
RD
IOCA
Interrupt-on-
Change
MCLRE
MCLRE
QD
EN
QD
EN
RD PORTA
Input
Pin
VSS
Q3
4.2.5.5 RA4/AN3/T1G/OSC2/CLKOUT
Figure 4-5 shows the diagram for this pin. The
RA4/AN3/T1G/OSC2/CLKOUT pin is configurable to
function as one of the following:
• a general purpose I/O
• an analog input for the ADC (except PIC16F631)
• a Timer1 gate input
• a crystal/resonator connection
• a clock output
FIGURE 4-5:
BLOCK DIAGRAM OF RA4
Data Bus
DQ
WR
WPUA
CK _Q
Analog⁽³⁾
Input Mode _CLK(1)
Modes
VDD
Weak
RD
WPUA
DQ
WR
PORTA
CK _Q
WR
TRISA
DQ
CK _Q
RD
TRISA
RD
PORTA
DQ
WR
IOCA
CK _Q
RD
IOCA
RABPU
Oscillator
Circuit
OSC1
CLKOUT
Enable
FOSC/4 1
0
CLKOUT
Enable
INTOSC/
RC/EC⁽²⁾
CLKOUT
Enable
Analog
Input Mode
VDD
I/O Pin
VSS
QD
EN
Q3
QD
EN
Interrupt-on-
Change
To T1G
To A/D Converter⁽⁴⁾
RD PORTA
Note 1: CLK modes are XT, HS, LP, LPTMR1 and CLKOUT
Enable.
2: With CLKOUT option.
3: ANSEL determines Analog Input mode.
4: Not implemented on PIC16F631.
DS41262E-page 66
© 2008 Microchip Technology Inc.