ST92F124/F150/F250 - GENERAL DESCRIPTION
1 GENERAL DESCRIPTION
The ST92F124/F150/F250 microcontroller is de-
veloped and manufactured by STMicroelectronics
using a proprietary n-well HCMOS process. Its
performance derives from the use of a flexible
256-register programming model for ultra-fast con-
text switching and real-time event response. The
intelligent on-chip peripherals offload the ST9 core
from I/O and data management processing tasks
allowing critical application tasks to get the maxi-
mum use of core resources. The new-generation
ST9 MCU devices now also support low power
consumption and low voltage operation for power-
efficient and low-cost embedded systems.
1.1.1 ST9+ Core
The advanced Core consists of the Central
Processing Unit (CPU), the Register File, the Inter-
rupt and DMA controller, and the Memory Man-
agement Unit. The MMU allows a single linear ad-
dress space of up to 4 Mbytes.
Four independent buses are controlled by the
Core: a 22-bit memory bus, an 8-bit register data
bus, an 8-bit register address bus and a 6-bit inter-
rupt/DMA bus which connects the interrupt and
DMA controllers in the on-chip peripherals with the
This multiple bus architecture makes the ST9 fam-
ily devices highly efficient for accessing on and off-
chip memory and fast exchange of data with the
The general-purpose registers can be used as ac-
cumulators, index registers, or address pointers.
Adjacent register pairs make up 16-bit registers for
addressing or 16-bit processing. Although the ST9
has an 8-bit ALU, the chip handles 16-bit opera-
tions, including arithmetic, loads/stores, and mem-
ory/register and memory/memory exchanges.
The powerful I/O capabilities demanded by micro-
controller applications are fulfilled by the
ST92F150/F124 with 48 (64-pin devices) or 77
(100-pin devices) I/O lines dedicated to digital In-
put/Output and with 80 I/O lines by the ST92F250.
These lines are grouped into up to ten 8-bit I/O
Ports and can be configured on a bit basis under
software control to provide timing, status signals,
an address/data bus for interfacing to the external
memory, timer inputs and outputs, analog inputs,
external interrupts and serial or parallel I/O. Two
memory spaces are available to support this wide
range of configurations: a combined Program/
Data Memory Space and the internal Register File,
which includes the control and status registers of
the on-chip peripherals.
1.1.2 External Memory Interface
100-pin devices have a 22-bit external address
bus allowing them to address up to 4M bytes of ex-
ternal memory. 64-pin devices have an 11-bit ex-
ternal address bus for addressing up to 2K bytes.
1.1.3 On-chip Peripherals
Two 16-bit Multifunction Timers, each with an 8 bit
Prescaler and 12 operating modes allow simple
use for complex waveform generation and meas-
urement, PWM functions and many other system
timing functions by the usage of the two associat-
ed DMA channels for each timer.
On 100-pin devices, two Extended Function Tim-
ers provide further timing and signal generation
A Standard Timer can be used to generate a sta-
ble time base independent from the PLL.
An I2C interface (two in the ST92F250) provides
fast I2C and Access Bus support.
The SPI is a synchronous serial interface for Mas-
ter and Slave device communication. It supports
single master and multimaster systems.
A J1850 Byte Level Protocol Decoder is available
(on some devices only) for communicating with a
The bxCAN (basic extended) interface supports
2.0B Active protocol. It has 3 transmit mailboxes, 2
independent receive FIFOs and 8 filters.
In addition, there is an 16 channel Analog to Digital
Converter with integral sample and hold, fast con-
version time and 10-bit resolution. In the 64-pin
version only 8 input channels are available.
There is one Multiprotocol Serial Communications
Interface with an integral generator, asynchronous
and synchronous capability (fully programmable
format) and associated address/wake-up option,
plus two DMA channels.
On some devices, there is an additional asynchro-
nous Serial Communications interface.
Finally, a programmable PLL Clock Generator al-
lows the usage of standard 3 to 5 MHz crystals to
obtain a large range of internal frequencies up to
24MHz. Low power Run (SLOW), Wait For Inter-
rupt, low power Wait For Interrupt, STOP and
HALT modes are also available.