ht82a836r Holtek Semiconductor Inc., ht82a836r Datasheet - Page 28

• Manufacturer Part Number: ht82a836r
• Description: Usb Audio Mcu
• Manufacturer: Holtek Semiconductor Inc.

set high. If this bit is not high, then the play interrupt fre-
quency will be 48kHz. When the interrupt is enabled, the
stack is not full and a Play Interrupt occurs, a subroutine
call to the Play Interrupt vector at location 10H, will take
place. When the interrupt is serviced, the Play Interrupt
request flag, PLAYF, will be automatically reset and the
EMI bit will be automatically cleared to disable other in-
terrupts.
Multi Function Interrupt
An additional interrupt known as the Multi-function inter-
rupt is provided. Unlike the other interrupts, this interrupt
has no independent source, but rather is formed from
three other existing interrupt sources, namely the Serial
Interface interrupt, the A/D Converter interrupt and the
External interrupt. The Multi-function interrupt is en-
abled by setting the EMF1I bit, which is bit 1 of the
INTC1 register. An actual Multi-function interrupt will be
initialised when the Multi-function interrupt request flag
MFF1 is set, this is bit 5 of the INTC1 register. When the
master interrupt global bit is set, the stack is not full and
the corresponding EMF1I interrupt enable bit is set, a
Multi-Function internal interrupt will be generated when
either a Serial Interface Interrupt, an A/D Converter In-
terrupt or an External Interrupt occurs. This will create a
subroutine call to its corresponding vector location
014H. When a Multi-function internal interrupt occurs,
the Multi-Function request flag MFF1 will be reset and
the EMI bit will be cleared to disable other interrupts.
However, it must be noted that the request flags from the
original source of the Multi-function interrupt, namely
the Serial Interface Interrupt, the A/D Converter or the
External Interrupt will not be automatically reset and
must be manually reset by the user.
Rev. 1.00
MFI1C Register
28
External Interrupt
The device contains an external interrupt function con-
trolled by the external pin INT. For an external interrupt
to occur, the pin must be setup as an interrupt input pin
by ensuring that the corresponding external interrupt
enable bit is first set. This is bit 2 in the MFI1C register
and known as EEI. An external interrupt is triggered by a
negative edge transition on the external interrupt pin
INT, after which the related interrupt request flag, EIF,
which is bit 6 in the MFI1C register, will be set. The inter-
rupt vector for the External Interrupt is the Multi-function
interrupt located at 014H. Therefore if the Multi-function
and External Interrupts are enabled, the stack is not full
and a negative logical transition occurs on pin INT, a
subroutine call to location 014H will take place. The
Multi-function Interrupt request flag MFF1 will be reset
automatically and the EMI bit will be cleared to disable
other interrupts. The External Interrupt flag will not be
reset automatically and needs to be reset manually by
the application program. The external interrupt pin INT
is pin-shared with I/O pin PE7 and can only be config-
ured as external interrupt pins if the interrupt is enabled
and if the pin is programmed as an input pins.
A/D Converter Interrupt
The device contains an internal A/D converter with its
own interrupt function. For an A/D Interrupt to occur, the
corresponding A/D Interrupt enable bit must be first set.
This is bit 1 in the MFI1C register and known as EADI.
An A/D Interrupt is generated when the A/D conversion
process is complete, after which the related interrupt re-
quest flag, ADF, which is bit 5 in the MFI1C register, will
be set. The interrupt vector for the A/D Interrupt is the
Multi-function interrupt located at 014H. Therefore if the
Multi-function and A/D Interrupt are enabled, the stack is
HT82A836R
March 20, 2008