ST72251
1 GENERAL DESCRIPTION
1.1 INTRODUCTION
The ST72251 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 de-
vice normally operates at a 16MHz oscillator fre-
quency. Under software control, the ST72251 may
be placed in either WAIT, SLOW 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 ST72251 features true
bit manipulation, 8x8 unsigned multiplication and
Figure 1. ST72251 Block Diagram
indirect addressing modes on the whole memory.
The device includes an on-chip oscillator, CPU,
program memory (ROM/OTP/EPROM versions),
RAM, 22 I/O lines and the following on-chip pe-
ripherals: Analog-to-Digital converter (ADC) with 6
multiplexed analog inputs, industry standard syn-
chronous SPI serial interface, I2C multiple Master/
Slave interface, digital Watchdog, two independ-
ent 16-bit Timers, one featuring an External Clock
Input, and both featuring Pulse Generator capabil-
ities, 2 Input Captures and 2 Output Compares.
OSCIN
OSCOU T
RESET
VDD
VSS
OSC
Internal
CLOCK
CONTROL
8-BIT CORE
ALU
PROGRAM
MEMORY
(4 - 8K Bytes)
RAM
(256 Bytes)
POWER
SU PPLY
I2C
PORT A
SP I
PORT B
TIMER A
PORT C
8-BIT ADC
TIMER B
W ATCHDOG
PA0 -> PA7
(8 bits)
PB0 -> PB7
(8 bits)
PC0 -> PC5
(6 bits)
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