ST10F272B_12 STMICROELECTRONICS [STMicroelectronics], ST10F272B_12 Datasheet - Page 98

• Manufacturer Part Number: ST10F272B_12
• Description: 16-bit MCU with 256 Kbyte Flash memory and 12/20 Kbyte RAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

System reset
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Figure 25. SW / WDT unidirectional RESET (EA = 0)
Bidirectional reset
As shown in the previous sections, the RSTOUT pin is driven active (low level) at the
beginning of any reset sequence (synchronous/asynchronous hardware, software and
watchdog timer resets). RSTOUT pin stays active low beyond the end of the initialization
routine, until the protected EINIT instruction (End of Initialization) is completed.
The Bidirectional Reset function is useful when external devices require a reset signal but
cannot be connected to RSTOUT pin, because RSTOUT signal lasts during initialization. It
is, for instance, the case of external memory running initialization routine before the
execution of EINIT instruction.
Bidirectional reset function is enabled by setting bit 3 (BDRSTEN) in SYSCON register. It
only can be enabled during the initialization routine, before EINIT instruction is completed.
When enabled, the open drain of the RSTIN pin is activated, pulling down the reset signal,
for the duration of the internal reset sequence (synchronous/asynchronous hardware,
synchronous software and synchronous watchdog timer resets). At the end of the internal
reset sequence the pull down is released and:
●
●
After a Short Synchronous Bidirectional Hardware Reset, if RSTF is sampled low 8
TCL periods after the internal reset sequence completion (refer to
Figure
sampled high the device simply exits reset state.
After a Software or Watchdog Bidirectional Reset, the device exits from reset. If RSTF
remains still low for at least 4 TCL periods (minimum time to recognize a Short
Hardware reset) after the reset exiting (refer to
21), the Short Reset becomes a Long Reset. On the contrary, if RSTF is
Doc ID 11917 Rev 3
Figure 26
and
Figure
ST10F272B/ST10F272E
Figure 20
27), the Software
and