ST7LITE20F2 STMicroelectronics, ST7LITE20F2 Datasheet - Page 33

• Manufacturer Part Number: ST7LITE20F2
• Description: 8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, DATA EEPROM, ADC, TIMERS, SPI
• Manufacturer: STMicroelectronics

Specifications of ST7LITE20F2

• 8 Kbytes Single Voltage Flash Program Memory With Read-out Protection, In-circuit Programming And In-application Programming (icp And Iap). 10k Write/erase Cycles Guaranteed, Data Retention: 20 years at 55˚C.
• Clock Sources: Internal 1% RC oscillator, crystal/ceramic resonator or external clock
• Five Power Saving Modes: Halt, Active-Halt, Wait and Slow, Auto Wake Up From Halt

SYSTEM INTEGRITY MANAGEMENT (Cont’d)
7.6.4 Register Description
SYSTEM INTEGRITY (SI) CONTROL/STATUS REGISTER (SICSR)
Read/Write
Reset Value: 0000 0xx0 (0xh)
Bit 7:5 = Reserved, must be kept cleared.
Bit 4 = WDGRF Watchdog reset flag
This bit indicates that the last Reset was generat-
ed by the Watchdog peripheral. It is set by hard-
ware (watchdog reset) and cleared by software
(writing zero) or an LVD Reset (to ensure a stable
cleared state of the WDGRF flag when CPU
starts).
Combined with the LVDRF flag information, the
flag description is given by the following table.
Bit 3 = LOCKED PLL Locked Flag
This bit is set and cleared by hardware. It is set au-
tomatically when the PLL reaches its operating fre-
quency.
0: PLL not locked
1: PLL locked
7
0
0
External RESET pin
RESET Sources
Watchdog
0
LVD
WDG
RF
LOCKED LVDRF AVDF AVDIE
LVDRF
0
0
1
WDGRF
X
1
0
0
Bit 2 = LVDRF LVD reset flag
This bit indicates that the last Reset was generat-
ed by the LVD block. It is set by hardware (LVD re-
set) and cleared by software (by reading). When
the LVD is disabled by OPTION BYTE, the LVDRF
bit value is undefined.
Bit 1 = AVDF Voltage Detector flag
This read-only bit is set and cleared by hardware.
If the AVDIE bit is set, an interrupt request is gen-
erated when the AVDF bit is set. Refer to
19
0: V
1: V
Bit 0 = AVDIE Voltage Detector interrupt enable
This bit is set and cleared by software. It enables
an interrupt to be generated when the AVDF flag is
set. The pending interrupt information is automati-
cally cleared when software enters the AVD inter-
rupt routine.
0: AVD interrupt disabled
1: AVD interrupt enabled
Application notes
The LVDRF flag is not cleared when another RE-
SET type occurs (external or watchdog), the
LVDRF flag remains set to keep trace of the origi-
nal failure.
In this case, a watchdog reset can be detected by
software while an external reset can not.
and to
DD
DD
over AVD threshold
under AVD threshold
Section 7.6.2.1
for additional details.
ST7LITE2
Figure
33/133
1