Rev. 1.10
102
November 26, 2019
Rev. 1.10
103
November 26, 2019
HT68FB240
USB Low Speed Flash MCU
The various interrupt enable bits, together with their associated request flags, are shown in the
Accompanying diagrams with their order of priority. Some interrupt sources have their own
individual vector while others share the same multi-function interrupt vector. Once an interrupt
subroutine is serviced, all the other interrupts will be blocked, as the global interrupt enable bit,
EMI bit will be cleared automatically. This will prevent any further interrupt nesting from occurring.
However, if other interrupt requests occur during this interval, although the interrupt will not be
immediately serviced, the request flag will still be recorded.
If an interrupt requires immediate servicing while the program is already in another interrupt service
routine, the EMI bit should be set after entering the routine, to allow interrupt nesting. If the stack
is full, the interrupt request will not be acknowledged, even if the related interrupt is enabled, until
the Stack Pointer is decremented. If immediate service is desired, the stack must be prevented from
becoming full. In case of simultaneous requests, the accompanying diagram shows the priority that
is applied. All of the interrupt request flags when set will wake-up the device if it is in SLEEP or
IDLE Mode, however to prevent a wake-up from occurring the corresponding flag should be set
before the device is in SLEEP or IDLE Mode.
INT0 Pin
INT0F
INT0E
EMI
04H
EMI
08H
EMI
0CH
EMI
10H
SIM
SIMF
SIME
EMI
20H
Interrupt
Name
Request
Flags
Enable
Bits
Master
Enable
Vector
EMI auto disabled
in ISR
Priority
High
Low
TM0P
T0PF
T0PE
TM0A
T0AF
T0AE
USB SIE
USBF
USBE
Interrupts contained within
Multi-Function Interrupts
xxE
Enable Bits
xxF
Request Flag, auto reset in ISR
Legend
xxF
Request Flag, no auto reset in ISR
EMI
24H
INT1 Pin
INT1F
INT1E
USB Setup
Token
USTF
USTE
LVD
LVDF
LVDE
EMI
1CH
M. Funct. 0
MF0F
MF0E
TM1P
T1PF
T1PE
TM1A
T1AF
T1AE
USB Endpoint 0
IN Token
UITF
UITE
EMI
14H
USB Endpoint 0
OUT Token
UOTF
UOTE
EMI
18H
Interrupt Structure