Clock Failure; Figure 11. Clock Tree Diagram; Figure 12. No Hse Clock Detected - STMicroelectronics STM32100B-EVAL User Manual

Running the demonstration

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. 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
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is displayed on the LCD screen.
Doc ID 16982 Rev 1
Figure 12 is displayed on the LCD screen.
UM0891