Holtek HT46R22, Handbook

Page: 20 / 162

HT46R24/HT46C24
Pin Name I/O
Configuration
Option
Description
PA0~PA2
PA3/PFD
PA4
PA5/INT
PA6/SDA
PA7/SCL
I/O
Pull-high
Wake-up
PA3 or PFD
PA6/PA7 or
SDA/SCL
Bidirectional 8-bit input/output port. Each individual bit on
this port can be configured as a wake-up input by a configu-
ration option. Software instructions determine if the pin is a
CMOS output or Schmitt Trigger input. A configuration op-
tion determines which bits on the port have pull-high resis-
tors. Pins PA3 and PA5 are pin-shared with PFD and INT
respectively. Pins PA6 and PA7 are pin-shared with SDA
and SCL respectively and are used to implement the I
2
C bus
function.
PB0/AN0
PB1/AN1
PB2/AN2
PB3/AN3
PB4/AN4
PB5/AN5
PB6/AN6
PB7/AN7
I/O Pull-high
Bidirectional 8-bit input/output port. Software instructions
determine if the pin is a CMOS output or Schmitt Trigger in-
put. A configuration option determines which bits on the port
have pull-high resistors. PB is pin-shared with the A/D input
pins. The A/D inputs are selected via software instructions.
Once selected as an A/D input, the I/O function and
pull-high resistor functions are disabled automatically.
PC0~PC7 I/O Pull-high
Bidirectional 8-bit input/output port. Software instructions
determine if the pin is a CMOS output or Schmitt Trigger in-
put. A configuration option determines if all pins on this port
have pull-high resistors.
PD0/PWM0
PD1/PWM1
PD2/PWM2
PD3/PWM3
PD4~PD7
I/O
Pull-high
I/O or PWM
Bidirectional 8-bit input/output port. Software instructions
determine if the pin is a CMOS output or Schmitt Trigger in-
put. A configuration option determines if all pins on this port
have pull-high resistors. The PWM0/PWM1/PWM2 and
PWM3 output pins are pin-shared with pins PD0/PD1/PD2
and PD3 respectively, selected via configuration options.
PF0~PF7 I/O Pull-high
Bidirectional 8-bit input/output port. Software instructions
determine if the pin is a CMOS output or Schmitt Trigger in-
put. A configuration option determines if all pins on this port
have pull-high resistors.
TMR0 I
¾
Timer/Event Counter 0 Schmitt Trigger input. No pull-high
resistor connected.
TMR1 I
¾
Timer/Event Counter 1 Schmitt Trigger input. No pull-high
resistor connected.
OSC1
OSC2 I
O
Crystal or RC
OSC1, OSC2 are connected to an external RC network or
external crystal (determined by configuration option) for the
internal system clock. For external RC system clock opera-
tion, OSC2 is an output pin for 1/4 system clock.
RES I
¾
Schmitt Trigger reset input. Active low.
VDD
¾ ¾
Positive power supply
VSS
¾ ¾
Negative power supply, ground
Chapter 1 Hardware Structure
11