Pin Assignments

16-bit Microcontroller HCS12H Family, Rev. 11.1

Freescale Semiconductor

13

PRELIMINARY

Table 2 Pin Descriptions

Note: Features shown in bold are not available in the 9S12H256 112 pin QFP package.

Note: Features shown in Italics are only available for the “Z” versions

Pin Name

Function 1

Pin Name

Function 2

Pin Name

Function 3

Pin Name

Function 4

Description

EXTAL





Crystal driver and external clock input pins. On reset all the

device clocks are derived from the EXTAL input frequency.

XTAL is the crystal output

XTAL





RESET





Active low bidirectional control signal that acts as an input to

initialize the MCU to a known start-up state, and an output

when an internal MCU function causes a reset.

TEST





Test Input

BKGD

TAGHI

MODC



Function 1: Pseudo-open-drain communication pin for the

background debug function.

Function 2: In MCU expanded modes of operation when in-

struction tagging is on, an input low on this pin during the falling

edge of E-clock tags the high half of the instruction word being

read into the instruction queue.

Function 3: At the rising edge during reset, the state of this pin

is latched to the MODC bit to set the MCU operating mode.

PAD[15:8]

AN[15:8]



Function 1: Port AD general purpose inputs

Function 2: Analog inputs (ATD)

PAD[7:0]

AN[7:0]

KWAD[7:0]



Function 1: Port AD general purpose inputs

Function 2: Analog inputs (ATD)

Function 3: Key wake-up input pins that can generate an inter-

rupt causing the MCU to exit STOP or WAIT mode.

PA[7:0]

FP[15:8]

ADDR[15:8]/D

ATA[15:8]



Function 1: Port A general purpose input or output pins.

Function 2: LCD frontplane segment driver output pin.

Function 3: In MCU expanded modes of operation, these pins

are used for the multiplexed external address and data bus.

PB[7:0]

FP[7:0]

ADDR[7:0]/DA

TA[7:0]



Function 1: Port B general purpose input or output pins.

Function 2: LCD frontplane segment driver output pin.

Function 3: In MCU expanded modes of operation, these pins

are used for the multiplexed external address and data bus.

PE7

FP22

XCLKS

NOACC

Function 1: Port E general purpose input or output pin

Function 2: LCD frontplane segment driver output pin

Function 3: The XCLKS signal selects between an external

clock or oscillator configuration during reset. This pin should

be at a logic high during reset if an external clock is used on

the EXTAL input pin. This pin should be at a logic low during

reset if an oscillator circuit is configured on EXTAL and XTAL.

Since this pin is an input with a pull-down device during reset,

if the pin is left floating, the default configuration is an

oscillator circuit on EXTAL and XTAL.

Function 4: During MCU expanded modes of operation, the

NOACC signal, when enabled, is used to indicate that the

current bus cycle is an unused or “free” cycle. This signal will

assert when the CPU is not using the bus.