ht82k96e Holtek Semiconductor Inc., ht82k96e Datasheet - Page 10

• Manufacturer Part Number: ht82k96e
• Description: Ht82k96e -- Usb Multimedia Keyboard Encoder 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

The TO flag can be affected only by system power-up, a
WDT time-out or executing the CLR WDT or HALT
instruction. The PDF flag can be affected only by ex-
ecuting the HALT or CLR WDT instruction or dur-
ing a system power-up.
The Z, OV, AC and C flags generally reflect the status of
the latest operations.
In addition, on entering the interrupt sequence or exe-
cuting the subroutine call, the status register will not be
pushed onto the stack automatically. If the contents of
the status are important and if the subroutine can cor-
rupt the status register, precautions must be taken to
save it properly.
Interrupt
The device provides an external interrupt and internal
timer/event counter interrupts. The Interrupt Control
Register (INTC;0BH) contains the interrupt control bits
to set the enable/disable and the interrupt request flags.
Once an interrupt subroutine is serviced, all the other in-
terrupts will be blocked (by clearing the EMI bit). This
scheme may prevent any further interrupt nesting. Other
interrupt requests may occur during this interval but only
the interrupt request flag is recorded. If a certain inter-
rupt requires servicing within the service routine, the
EMI bit and the corresponding bit of the INTC may be set
to allow interrupt nesting. If the stack is full, the interrupt
request will not be acknowledged, even if the related in-
terrupt is enabled, until the SP is decremented. If immedi-
ate service is desired, the stack must be prevented from
becoming full.
All these kinds of interrupts have a wake-up capability.
As an interrupt is serviced, a control transfer occurs by
pushing the program counter onto the stack, followed by
a branch to a subroutine at specified location in the pro-
gram memory. Only the program counter is pushed onto
the stack. If the contents of the register or status register
(STATUS) are altered by the interrupt service program
which corrupts the desired control sequence, the con-
tents should be saved in advance.
Rev. 2.00
Bit No.
0
1
2
3
4
5
6
7
USBF
Label
ET0I
ET1I
EMI
T0F
T1F
EUI
Controls the master (global) interrupt (1= enabled; 0= disabled)
Controls the USB interrupt (1= enabled; 0= disabled)
Controls the Timer/Event Counter 0 interrupt (1= enabled; 0= disabled)
Controls the Timer/Event Counter 1 interrupt (1= enabled; 0= disabled)
USB interrupt request flag (1= active; 0= inactive)
Internal Timer/Event Counter 0 request flag (1= active; 0= inactive)
Internal Timer/Event Counter 1 request flag (1= active; 0= inactive)
Unused bit, read as 0
INTC (0BH) Register
10
USB interrupts are triggered by the following USB
events and the related interrupt request flag (USBF; bit
4 of INTC) will be set.
When the interrupt is enabled, the stack is not full and
the external interrupt is active, a subroutine call to loca-
tion 04H will occur. The interrupt request flag (USBF)
and EMI bits will be cleared to disable other interrupts.
When PC Host access the FIFO of the HT82K96E, the
corresponding request bit of USR is set, and a USB in-
terrupt is triggered. So user can easy to decide which
FIFO is accessed. When the interrupt has been served,
the corresponding bit should be cleared by firmware.
When HT82K96E receive a USB Suspend signal from
Host PC, the suspend line (bit0 of USC) of the
HT82K96E is set and a USB interrupt is also triggered.
Also when HT82K96E receive a Resume signal from
Host PC, the resume line (bit3 of USC) of HT82K96E is
set and a USB interrupt is triggered.
Whatever there are USB reset signal is detected, the
USB interrupt is triggered.
The internal Timer/Event Counter 0 interrupt is initial-
ized by setting the Timer/Event Counter 0 interrupt re-
quest flag (; bit 5 of INTC), caused by a timer 0 overflow.
When the interrupt is enabled, the stack is not full and
the T0F bit is set, a subroutine call to location 08H will
occur. The related interrupt request flag (T0F) will be re-
set and the EMI bit cleared to disable further interrupts.
The internal timer/even counter 1 interrupt is initialized
by setting the Timer/Event Counter 1 interrupt request
flag (;bit 6 of INTC), caused by a timer 1 overflow. When
the interrupt is enabled, the stack is not full and the T1F
is set, a subroutine call to location 0CH will occur. The
related interrupt request flag (T1F) will be reset and the
EMI bit cleared to disable further interrupts.
The access of the corresponding USB FIFO from PC
The USB suspend signal from PC
The USB resume signal from PC
USB Reset signal
Function
October 11, 2007
HT82K96E