Datasheet

Chapter 2 Pins and Connections
MC9RS08KA2 Series Data Sheet, Rev. 4
20 Freescale Semiconductor
cables and the absolute value of the internal pullup device play almost no role in determining rise and fall
times on the BKGD pin.
2.4.4 General-Purpose I/O and Peripheral Ports
The remaining pins are shared among general-purpose I/O and on-chip peripheral functions such as timers
and analog comparator. Immediately after reset, all of these pins are configured as high-impedance
general-purpose inputs with internal pullup/pulldown devices disabled.
NOTE
To avoid extra current drain from floating input pins, the reset initialization
routine in the application program should either enable on-chip
pullup/pulldown devices or change the direction of unused pins to outputs.
Table 2-1. Pin Sharing Reference
Pin Name Direction Pullup/Pulldown
1
1
SWC is software-controlled pullup/pulldown resistor; the register is associated with the respective port.
Alternative Functions
2
2
Alternative functions are listed lowest priority first. For example, GPIO is the lowest priority alternative function of the
PTA0 pin; ACMP+ is the highest priority alternative function of the PTA0 pin.
V
DD
—— Power
V
SS
— — Ground
PTA0 I/O SWC PTA0
KBIP0
ACMP+
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)
Analog comparator input
PTA1 I/O SWC PTA1
KBIP1
ACMP-
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)
Analog comparator input
PTA2 I SWC
4
PTA2
KBIP2
TCLK
RESET
V
PP
General-purpose input
Keyboard interrupt (stop/wait wakeup only)
Modulo timer clock source
Reset
V
PP
PTA3 I/O
3
3
Output-only when configured as PTA3 function.
—
4
4
When PTA2 or PTA3 is configured as RESET or BKGD/MS, respectively, pullup is enabled. When V
PP
is attached,
pullup/pulldown is disabled automatically.
PTA3
ACMPO
BKGD
MS
General-purpose output
Analog comparator output
Background debug data
Mode select
PTA4
5
5
This pin is not available in 6-pin package. Enabling either the pullup or pulldown device is recommended to prevent extra
current leakage from the floating input pin.
I/O SWC PTA4
KBIP4
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)
PTA5
5
I/O SWC PTA5
KBIP5
General-purpose input/output (GPIO)
Keyboard interrupt (stop/wait wakeup only)