W78C438C
8-BIT MICROCONTROLLER
Publication Release Date: July 1998
- 1 -
Revision A1
GENERAL DESCRIPTION
The W78C438C is a high-performance single-chip CMOS 8-bit microcontroller that is a derivative of
the W78C58 microcontroller family. The W78C438C is functionally compatible with the W78C32,
except that it provides either a 64 KB program/1 MB data memory address or memory-mapped chip
select logic, five general I/O ports, and four external interrupts.
In the W78C32, two I/O ports, Port 1 and Port 3, are available for general-purpose use (Port 3 also
supports alternative functions), and Port 2 and Port 0 are used as the address bus and data bus,
respectively. To enable Port 0 and Port 2 to also be used as general purpose I/O ports, the
W78C438C provides two dedicated address ports (AP5 and AP6) that serve as address output for 64
KB of memory and one address/data port (DP4) that serves as ROM code input and external RAM
data input/output. Unlike the W78C32, this product does not require an external latch device for
multiplexing low byte addresses. The W78C438C also provides four pins (AP7.0
−
AP7.3) to support
either 64 KB program/1 MB data memory space or memory-mapped chip select logic, one parallel I/O
port (Port 8) without bit addressing mode, and two additional external interrupts (
INT2
,
INT3
) .
The W78C438C is programmed in a manner fully compatible with that used to program the W78C32,
except that the external data RAM is accessed by the "MOVX @Ri" instruction. Address paging is
performed by loading page addresses into the HB (high byte) register, which is not a standard register
in the W78C32, before execution of the "MOVX @Ri" instruction.
FEATURES
•
8-bit CMOS microcontroller
•
Fully static design
•
DC to 40 MHz operation
•
ROM-less operation
•
256-byte on-chip scratchpad RAM
•
Either 64 KB program/1 MB data memory address space or 4 memory-mapped chip select pins
•
One 8-bit data/address port
•
Two 8-bit and one 4-bit (optional) address ports
•
Five 8-bit bidirectional I/O ports
−
Four 8-bit bit-addressable I/O ports and one 8-bit parallel I/O port
•
Eight-source, two-level interrupt capability
•
Three 16-bit timer/counters
•
Four external interrupts
•
One full-duplex serial channel
•
Built-in power management
−
Idle mode
−
Power-down mode
•
Packages:
−
84-pin PLCC: W78C438CP-24/40
−
100-pin PQFP: W78C438CF-24/40
