ST7232AJ2 STMicroelectronics, ST7232AJ2 Datasheet - Page 25

• Manufacturer Part Number: ST7232AJ2
• Description: 8-BIT MCU WITH 8K FLASH/ROM, ADC, 4 TIMERS, SPI, SCI INTERFACE
• Manufacturer: STMicroelectronics

Specifications of ST7232AJ2

• Hdflash Endurance: 100 cycles, data retention
• Clock Sources: crystal/ceramic resonator oscillators and bypass for external clock
• Four Power Saving Modes: Halt, Active-Halt, Wait and Slow
• Main Clock Controller With: Real time base, Beep and Clock-out capabilities
• Two 16-bit Timers With: 2 input captures, 2 output compares, PWM and pulse generator modes

6.3 RESET SEQUENCE MANAGER (RSM)
6.3.1 Introduction
The reset sequence manager includes two RE-
SET sources as shown in
■
■
These sources act on the RESET pin and it is al-
ways kept low during the delay phase.
The RESET service routine vector is fixed at ad-
dresses FFFEh-FFFFh in the ST7 memory map.
The basic RESET sequence consists of 3 phases
as shown in
■
■
■
The 256 or 4096 CPU clock cycle delay allows the
oscillator to stabilise and ensures that recovery
has taken place from the Reset state. The shorter
or longer clock cycle delay should be selected by
option byte to correspond to the stabilization time
of the external oscillator used in the application.
Figure 13. Reset Block Diagram
External RESET source pulse
Internal WATCHDOG RESET
Active Phase depending on the RESET source
256 or 4096 CPU clock cycle delay (selected by
option byte)
RESET vector fetch
RESET
Figure
12:
V
Figure
DD
R
ON
13:
Filter
The RESET vector fetch phase duration is 2 clock
cycles.
Figure 12. RESET Sequence Phases
6.3.2 Asynchronous External RESET pin
The RESET pin is both an input and an open-drain
output with integrated R
This pull-up has no fixed value but varies in ac-
cordance with the input voltage. It can be pulled
low by external circuitry to reset the device. See
Electrical Characteristic section for more details.
A RESET signal originating from an external
source must have a duration of at least t
order to be recognized (see
tection is asynchronous and therefore the MCU
can enter reset state even in HALT mode.
GENERATOR
PULSE
Active Phase
256 or 4096 CLOCK CYCLES
WATCHDOG RESET
INTERNAL RESET
RESET
ON
weak pull-up resistor.
Figure
INTERNAL
RESET
14). This de-
ST7232A
VECTOR
h(RSTL)in
FETCH
25/157
in
1