The ST9040 is a ROM member of the ST9 family of
microcontrollers, completely developed and pro-
duced by SGS-THOMSON Microelectronics using
a proprietary n-well HCMOS process.
The ST9040 peripheral and functional actions are
fully compatible throughout the ST903x/4x family.
This datasheet will thus provide only information
specific to this ROM device.
THE READER IS ASKED TO REFER TO THE
DATASHEET OF THE ST9036 ROM-BASED DE-
VICE FOR FURTHER DETAILS.
The nucleus of the ST9040 is the advanced Core
which includes the Central Processing Unit (CPU),
the Register File, a 16 bit Timer/Watchdog with 8
bit Prescaler, a Serial Peripheral Interface support-
ing S-bus, I2C-bus and IM-bus Interface,plus two 8
bit I/O ports. The Core has independent memory
and register buses allowing a high degree of pipe-
lining to add to the efficiency of the code execution
speed of the extensive instruction set. The power-
ful I/O capabilities demanded by microcontroller
applications are fulfilled by the ST9040 with up to
56 I/O lines dedicated to digital Input/Output.
These lines are grouped into up to seven 8 bit I/O
Ports and can be configured on a bit basis under
software control to provide timing, status signals,
an address/databus for interfacing external mem-
ory, timer inputs and outputs, analog inputs, exter-
nal interrupts and serial or parallel I/O with or
Three basic memory spaces are available to support
this wide range of configurations: Program Memory
(internaland external), Data Memory (internaland ex-
ternal)andtheRegisterFile, which includesthecontrol
andstatus registers of theon-chip peripherals.
Two 16 bit MultiFunction Timers, each with an 8 bit
Prescaler and 13 operating modes allow simple
use for complex waveform generation and meas-
urement, PWM functions and many other system
timing functionsby the usage of the two associated
DMA channels for each timer. In addition there is
an 8 channel Analog to Digital Converter with inte-
gral sample and hold, fast 11µs conversion time
and 8 bit resolution. An Analog Watchdog feature
is included for two input channels.
Completing the device is a full duplex Serial Com-
munications Interface with an integral 110 to
375,000 baud rate generator, asynchronous and
1.5Mbyte/s synchronous capability (fully program-
mable format) and associated address/wake-up
option, plus two DMA channels.