STFPC320 STMicroelectronics, STFPC320 Datasheet - Page 47

• Manufacturer Part Number: STFPC320
• Description: Front Panel Controller/driver With Standby Power Management And Real-time Clock
• Manufacturer: STMicroelectronics

STFPC320
14
Note:
Description:
Interrupt flags
The interrupt is sent on the IRQ_N/SQW pin when any one of the events occur: FP key
pressed, RC key pressed, PIN_AV8 transitions to a high or RTC events (watchdog timer,
alarm, oscillator fail). Simultaneously, the interrupt flags are set.
The micro-processor can read the interrupt flags by sending the “01100011” command.
After decoding this command, STFPC320 output one byte data as described below to
indicate the source of interrupt.
Default value of the register is 00h.
MS
B
FPK
FPK
In the normal mode of operation (System is not in Standby), the events described
below will cause any of the b4 to b7 bit to be set to 1 and IRQ_N/SQW will be
asserted low:
b4: RTC events
b5: PIN_AV8 transition to High
b6: Valid remote control key detection
b7: Front panel key detection
Having detected the assertion of IRQ_N/SQW pin, micro-processor should then read
the interrupt buffer to determine the external event causing the interrupt. Once read,
the buffer will be cleared and IRQ_N/SQW is released.
In the wake-up operation (System is in Standby), the events described below will
cause any of the b0 to b3 bit to be set to 1 and wake up occurs (STBY output is set to
Low):
b0: RTC events
b1: PIN_AV8 transition to High
b2: Valid remote control hotkeys detection
b3: Front panel Hotkeys detection
Once wake up occurs, micro-processor should pull READY to High to indicate to
STFPC320 of a proper boot-up. STFPC320 will then assert the interrupt to indicate
that an external event has been occurred. Micro-processor should then read the
interrupt buffer to determine the event causing the wake up.
When the interrupt is caused by RTC, micro-processor should read the RTC interrupt
flag at address 0Fh to determine the specific RTC event: alarm, Watchdog timer of
RTC or Oscillator fail.
b7
Normal operation
b6
RCK
RCK
PIN_AV8
PIN_AV8
b5
Watchdog
Watchdog
value of
value of
or OFIE
or OFIE
Preset-
Preset-
RTC or
RTC or
b4
FP hot
FP hot
b3
key
key
b2
RC hot
RC hot
key
key
Wake-up operation
PIN_AV8
PIN_AV8
b1
Interrupt flags
Watchdog
Watchdog
value of
value of
or OFIE
or OFIE
Preset-
Preset-
RTC or
RTC or
b0
LSB
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