COP8SA-DM National Semiconductor, COP8SA-DM Datasheet - Page 30

• Manufacturer Part Number: COP8SA-DM
• Description: MODULE DEBUGGING FOR COP8SA
• Manufacturer: National Semiconductor

Specifications of COP8SA-DM

• Module/board Type: Debugger Module
• For Use With/related Products: Cop 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *COP8SA-DM

Latches
Ports
Memory Mapped I/O or Ports
User-Configurable I/O
Dedicated I/O
1-18
MICROCONTROLLER BASICS
output voltage on the pin corresponds to a single bit of
information.
Often used to store outgoing/incoming bits.
A port is a group of pins used for sending or receiving in-
formation. A port may have all outputs, all inputs, or a
combination input/output pins. Some ports are bidirec-
tional. Port pins may be used together for parallel com-
munication or individually as control signals or serial
communication.
Each port (group of pins) is assigned an address as if it
were a register (byte of data) in memory. Writing to an
address assigned to a port causes the pins associated
with the addressed port to be forced high or low accord-
ing to the value written. If ports are not memory
mapped, special I/O instructions have to be used to ac-
cess them.
User-configurable ports or I/O may be set by the user to
be inputs or outputs (some ports are fixed in hardware
to be inputs or outputs). A configuration or control reg-
ister is generally associated with a user-configurable
port. Setting or resetting the bits in this special register
configures the associated port pins the be inputs or out-
puts. Some user-configurable I/O ports only allow the
user to select pins of a particular port to be all inputs or
all outputs. Other devices allow the user to specify the
configuration of each individual pin of a port. Some
pins/ports have user selectable special functions.
Dedicated I/O pins can only be used for one particular
function. For example, the RESET pin can rarely be
used for anything other than resetting the device. Other
such pins might be the clock pin.