
Rev.1.00
2004.03.23
page 7 of 320
M306H3MC-XXXFP/FCFP
Table 1.5.1 Pin Description
VCC, VSS
CNVSS
Signal name
Power supply
input
CNVSS
Apply 4.75 V to 5.25 V to the Vcc pin. Apply 0 V to the Vss pin.
Function
This pin switches between processor modes. Connect this pin to VSS pin
when after a reset you want to start operation in single-chip mode
(memory expansion mode) or the VCC pin when starting operation in
microprocessor mode.
Pin name
Input
I/O type
XIN
XOUT
Clock input
Clock output
These pins are provided for the main clock generating circuit input/
output. Connect a ceramic resonator or crystal between the XIN and the
XOUT pins. To use an externally derived clock, input it to the XIN pin and
Input
Output
Reset input
“L” on this input resets the microcomputer.
Input
RESET
BYTE
External data
bus width
select input
This pin selects the width of an external data bus. A 16-bit width is
selected when this input is “L”; an 8-bit width is selected when this input
is “H”. This input must be fixed to either “H” or “L”. Connect this pin to
the VSS when single-chip mode.
Input
AVCC
Analog power
supply input
This pin is a power supply input for the A-D converter. Connect this
pin to VCC.
leave the XOUT pin open.
VREF
Reference
voltage input
This pin is a reference voltage input for the A-D converter.
Input
P00 to P07
I/O port P0
This is an 8-bit CMOS I/O port. This port has an input/output select
direction register, allowing each pin in that port to be directed for input or
output individually.
If any port is set for input, selection can be made for it in a program
whether or not to have a pull-up resistor in 4 bit units. This selection is
unavailable in memory extension and microprocessor modes.
This port can function as input pins for the A-D converter when so
selected in a program.
Input/output
AVSS
This pin is a power supply input for the A-D converter. Connect this
pin to VSS.
Analog power
supply input
P10 to P17
I/O port P1
This is an 8-bit I/O port equivalent to P0. Pins in this port also function
as INT interrupt input pins as selected by software.
Input/output
D0 to D7
When set as a separate bus, these pins input and output data (D0 to D7).
Input/output
D8 to D15
When set as a separate bus, these pins input and output data (D8 to D15).
Input/output
P20 to P27
I/O port P2
This is an 8-bit I/O port equivalent to P0. This port can function as input
pins for the A-D converter when so selected in a program.
Input/output
A0 to A7
These pins output 8 low-order address bits (A0 to A7).
Output
A0/D0 to
A7/D7
If the external bus is set as an 8-bit wide multiplexed bus, these pins
input and output data (D0 to D7) and output 8 low-order address bits
(A0 to A7) separated in time by multiplexing.
Input/output
A0, A1/D0
to A7/D6
If the external bus is set as a 16-bit wide multiplexed bus, these pins
input and output data (D0 to D6) and output address (A1 to A7) separated
in time by multiplexing. They also output address (A0).
Output
Input/output
P30 to P37
I/O port P3
This is an 8-bit I/O port equivalent to P0.
Input/output
A8 to A15
These pins output 8 middle-order address bits (A8 to A15).
Output
A8/D7,
A9 to A15
If the external bus is set as a 16-bit wide multiplexed bus, these pins
input and output data (D7) and output address (A8) separated in time
by multiplexing. They also output address (A9 to A15).
Input/output
Output
P40 to P47
I/O port P4
This is an 8-bit I/O port equivalent to P0.
Input/output
Output
CS0 to CS3,
A16 to A19
These pins output CS0 to CS3 signals and A16 to A19. CS0 to CS3 are
chip select signals used to specify an access space. A16 to A19 are 4
high-order address bits.