2.5 to 5.5V Supply Operating Range

4MHz Maximum Clock Frequency

Fully Static operation

-40° to +85°C Operating Temperature Range

Run, Wait, Stop and RAM Retention modes

User ROM: 6,144 bytes

Data RAM: 224 bytes

EEPROM: 256 bytes

28 pin Dual-in-Line and SO plastic packages

22 Bidirectional I/O lines

6 Interrupt Wake-Up programmable input lines

16-bit Timer with Input Capture and dual
Output Compare

2V RAM Data Retention mode

Master Reset and Power-On Reset

Maskable Options for:
– Input Capture (ICAP) and Output Compare
(OCMP) signal pinouts
– PORT C Wake-Up function
– PORT A Open-Drain outputs
– PORTS A and B input Pull-Ups
– Watchdog Enabled/Disabled following Reset
– Watchdog Enabled during WAIT mode

8-bit Data Manipulation

63 Basic Instructions

17 main Addressing Modes

8x8 Unsigned Multiply instruction

True Bit Manipulation

Complete Development Support on PC/DOS
Real-Time Emulator

Full Software Package (Cross-Assembler,
Debugger)

Full Hardware Emulator

EPROM and OTP support

1 GENERAL DESCRIPTION
1.1 INTRODUCTION
The ST7294 HCMOS Microcontroller Unit is a
member of the ST7 family of Microcontrollers. The
device is based on an industry-standard 8-bit core
and features an enhanced instruction set. The
CPU may be driven by an external 4MHz clock
when the device is operated with a 5V supply, or
by a 2MHz clock when operated with a 3V supply.
Thanks to the fully static design, operation is possible
down to DC. Under software control, the
ST7294 may be placed in either WAIT or HALT
modes, thus reducing power consumption. The
enhanced instruction set and addressing modes
afford real programming potential. In addition to
standard 8-bit data management, the ST7294 features
true bit manipulation, 8x8 unsigned multiplication
and indirect addressing modes. The device
includes a CPU, ROM, RAM, EEPROM, I/O, an
on-chip oscillator and a timer with input capture
and dual output compare systems.