Pin Name I/O
Configuration
Option
Description
OSC1/PC3
OSC2/PC4
I
O
Pull-high
Crystal or RC or
Int. RC+I/O or
Int. RC+RTC
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 op
-
eration, OSC2 is an output pin for 1/4 system clock.
These two pins can also be optioned as an RTC oscillator
(32768Hz) or I/O lines. In these two cases, the system clock
comes from an internal RC oscillator whose nominal fre
-
quency at 5V has 4 options, 3.2MHz, 1.6MHz, 800kHz,
400kHz. If the pins are used as normal I/O pins, then
pull-high options are available. If used as oscillator pins,
bits PC3 and PC4 will be free for use by the application pro
-
gram. In this case the pull-high options are disabled.
RES I
¾
Schmitt Trigger reset input. Active low.
VDD
¾¾
Positive power supply
VSS
¾¾
Negative power supply, ground
Note 1. Each pin on PA can be programmed through a configuration option to have a wake-up function.
2. Individual pins cannot be selected to have pull-high resistors. If the pull-high configuration
is chosen for a particular port, then all input pins on this port will be connected to pull-high
resistors.
HT48R30A-1/HT48C30-1
Pin Name I/O
Configuration
Option
Description
PA0~PA7 I/O
Pull-high
Wake-up
Schmitt Trigger
Bidirectional 8-bit input/output port. Each pin can be config-
ured as a wake-up input by configuration option. Software
instructions determine if the pin is a CMOS output or input.
Configuration options determine if all pins on this port have
pull-high resistors and if the inputs are Schmitt Trigger or
non Schmitt Trigger.
PB0/BZ
PB1/BZ
PB2~PB7
I/O
Pull-high
I/O or BZ/BZ
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. Pins PB0 and PB1 are pin-shared
with BZ and BZ
, respectively.
PC0/TMR
PC1~PC5
I/O Pull-high
Bidirectional 6-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. PC0 is pin-shared with external
timer pin TMR.
Chapter 1 Hardware Structure
9
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