ST7FOXK1 STMicroelectronics, ST7FOXK1 Datasheet - Page 79

• Manufacturer Part Number: ST7FOXK1
• Description: Low cost flash 8bit micro
• Manufacturer: STMicroelectronics

Specifications of ST7FOXK1

• 4 To 8 Kbytes Single Voltage Extended Flash (xflash) Program Memory With Read-out Protection In-circuit Programming And In-application Programming (icp And Iap) Endurance: 1K write/erase cycles guaranteed Data retention
• Clock Sources: Internal trimmable 8 MHz RC oscillator, auto wakeup internal low power - low frequency oscillator, crystal/ceramic resonator or external clock
• Five Power Saving Modes: Halt, Active-Halt, Auto Wakeup from Halt, Wait and Slow
• A/d Converter: up to 10 input channels

ST7FOXF1, ST7FOXK1, ST7FOXK2
10
10.1
10.1.1
10.1.2
10.1.3
On-chip peripherals
Watchdog timer (WDG)
Introduction
The Watchdog timer is used to detect the occurrence of a software fault, usually generated
by external interference or by unforeseen logical conditions, which causes the application
program to abandon its normal sequence. The Watchdog circuit generates an MCU reset on
expiry of a programmed time period, unless the program refreshes the counter’s contents
before the T6 bit becomes cleared.
Main features
Functional description
The counter value stored in the CR register (bits T[6:0]), is decremented every 16000
machine cycles, and the length of the timeout period can be programmed by the user in 64
increments.
If the watchdog is activated (the WDGA bit is set) and when the 7-bit timer (bits T[6:0]) rolls
over from 40h to 3Fh (T6 becomes cleared), it initiates a reset cycle pulling low the RESET
pin for typically 30µs.
Figure 34. Watchdog block diagram
Programmable free-running downcounter (64 increments of 16000 CPU cycles)
Programmable reset
Reset (if watchdog activated) when the T6 bit reaches zero
Optional reset on HALT instruction (configurable by option byte)
Hardware Watchdog selectable by option byte
f
CPU
WDGA
RESET
T6
T5
WATCHDOG CONTROL REGISTER (CR)
7-BIT DOWNCOUNTER
CLOCK DIVIDER
T4
÷16000
T3
T2
T1
T0
On-chip peripherals
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