
General Description
MC68HC812A4 Data Sheet, Rev. 7
22
Freescale Semiconductor
RxD1
PS2
Receive pin for SCI1
TxD1
PS3
Transmit pin for SCI1
SDI/MISO
PS4
Master in/slave out pin for SPI
SDO/MOSI
PS5
Master out/slave in pin for SPI
SCK
PS6
Serial clock for SPI
SS
PS7
Slave select output for SPI in master mode; slave select input in slave mode
IOC7–IOC0
Port T
Input capture or output compare channels and pulse accumulator input
1. The MCU operates from a single power supply. Use the customary bypass techniques as very fast signal transitions occur
on MCU pins.
2. Separate power supply pins allow the ADC power supply to be bypassed independently of the MCU power supply.
3. Out of reset the frequency applied to EXTAL is twice the desired E-clock rate. On reset all device clocks are derived from
the EXTAL input frequency. XTAL is the crystal output.
4. LSTRB is the exclusive-NOR of A0 and the internal SZ8 signal. SZ8 indicates the size 16/8 access.
5. After reset, MODA and MODB can be configured as instruction queue tracking signals IPIPE0 and IPIPE1 or as gener-
al-purpose I/O pins.
Table 1-3. Port Descriptions
Port
Direction
Function
Port A
I/O
Single-chip modes: general-purpose I/O
Expanded modes: external address bus ADDR15–ADDR8
Port B
I/O
Single-chip modes: general-purpose I/O
Expanded modes: external address bus ADDR7–ADDR0
Port C
I/O
Single-chip modes: general-purpose I/O
Expanded wide modes: external data bus DATA15–DATA8
Expanded narrow modes: external data bus DATA15–DATA8/DATA7–DATA0
Port D
I/O
Single-chip and expanded narrow modes: general-purpose I/O
External data bus DATA7–DATA0 in expanded wide mode(1)
1. Key wakeup interrupt request can occur when an input goes from high to low.
Port E
I/O and I(2)
2. PE1 and PE0 are input-only pins.
External interrupt request inputs, mode select inputs, bus control signals
General-purpose I/O
Port F
I/O
Chip select
General-purpose I/O
Port G
I/O
Memory expansion
General-purpose I/O
Port H
I/O
Key wakeup(3)
General-purpose I/O
3. Key wakeup interrupt request can occur when an input goes from high to low.
Port J
I/O
Key wakeup(4)
General-purpose I/O
4. Key wakeup interrupt request can occur when an input goes from high to low or from low to high.
Port S
I/O
SCI and SPI ports
General-purpose I/O
Port T
I/O
Timer port
General-purpose I/O
Port AD
I
ADC port
General-purpose input
Table 1-2. Pin Descriptions (Continued)
Pin
Port
Description