ST92185B STMicroelectronics, ST92185B Datasheet - Page 57

• Manufacturer Part Number: ST92185B
• Description: 16k/24k/32k Rom Hcmos Mcu With On-screen-display
• Manufacturer: STMicroelectronics

4 RESET AND CLOCK CONTROL UNIT (RCCU)
4.1 INTRODUCTION
The Reset Control Unit comprises two distinct sec-
tions:
– An oscillator that uses an external quartz crystal.
– The Reset/Stop Manager, which detects and
4.2 RESET / STOP MANAGER
The RESET/STOP Manager resets the device
when one of the three following triggering events
occurs:
– A hardware reset, consequence of a low level on
– A software reset, consequence of an HALT in-
Figure 29. Reset Overview
n
flags Hardware, Software and Watchdog gener-
ated resets.
the RESET pin.
struction when enabled.
RESET
RESETO
Memorized
Build-up Counter
Reset
ST92185B - RESET AND CLOCK CONTROL UNIT (RCCU)
– A Watchdog end of count.
The RESET input is schmitt triggered.
Note: The memorized Internal Reset (called RE-
SETO) will be maintained active for a duration of
32768 Oscin periods (about 8 ms for a 4 MHz crys-
tal) after the external input is released (set high).
This RESETO internal Reset signal is output on
the I/O port bit P3.7 (active low) during the whole
reset phase until the P3.7 configuration is changed
by software. The true internal reset (to all macro-
cells) will only be released 511 Reference clock
periods after the Memorized Internal reset is re-
leased.
It is possible to know which was the last RESET
triggering event, by reading bits 5 and 6 of register
SDRATH.
RCCU
True
Internal
Reset
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