UM1011
Running the demonstration
Doc ID 18064 Rev 1
17/49
Figure 11.
Clock tree diagram
2.5.2 Clock
failure
At any point of the demonstration, if no clock is present on OSC_IN (broken or disconnected
crystal), the message shown in
Figure 12
is displayed on the LCD screen.
Figure 12.
No HSE clock detected
If no clock is detected, the clock security system (CSS) feeds the MCU with the HSI OSC
used as an emergency clock.
The demonstration will not restart as long as the 8 MHz crystal is not present. You must
connect the crystal before starting the demonstration. Connecting the 8 MHz crystal after
reset may not restart the demonstration correctly.
If the 8 MHz crystal is not reconnected in the next few seconds, the MCU enters Standby
mode. If the 8 MHz crystal is reconnected within a few seconds, a system reset is
generated.
When a timeout occurs, the MCU enters Standby mode and the message shown in
Figure 13
is displayed on the LCD screen.
0,,
(3%
OSCILLATOR
-(Z
!("PRESCALER
393#,+
-(ZMAX
!0"PRESCALER
!0"PRESCALER
0#,+TO!0"
PERIPHERALS
4)-
§IF!0"PRESCALER
ELSE§MULTIPLIER
-(Z
-(Z
-(Z
0#,+TO!0"
PERIPHERALS
4)-
-(Z
-(Z
-(Z
,3%
OSCILLATOR
K(Z
24#
K(Z
(3%
02%$)6
-ULTIPLICATORX
-(ZX
§IF!0"PRESCALER
ELSE§MULTIPLIER
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