HT95R54/HT95R55

Rev. 1.00

40

March 3, 2010

A u t o m a t i c a l l y C l e a r e d b y I S R

- e x p e c t f o r P C 0 F , P C 5 F a n d P C 7 F

M a n u a l l y S e t o r C l e a r e d b y S o f t w a r e

E x t e r n a l I n t e r r u p t

R e q u e s t F l a g E I F

T i m e r / E v e n t C o u n t e r 0

I n t e r r u p t R e q u e s t F l a g T 0 F

T i m e r / E v e n t C o u n t e r 1

I n t e r r u p t R e q u e s t F l a g T 1 F

E E I

E T 0 I

E T 1 I

E M I

A u t o m a t i c a l l y D i s a b l e d b y I S R

C a n b e E n a b l e d M a n u a l l y

P r i o r i t y

H i g h

I n t e r r u p t

P o l l i n g

P e r i p h e r a l I n t e r r u p t

R e q u e s t F l a g P E R F

E P E R I

R T C I n t e r r u p t

R e q u e s t F l a g R T C F

E R T C I

L o w

M u l t i - f u n c t i o n I n t e r r u p t

R e q u e s t F l a g M F F

E M F I

P C 0 I n t e r r u p t

R e q u e s t F l a g P C 0 F

E P C 0 I

P C 5 I n t e r r u p t

R e q u e s t F l a g P C 5 F

E P C 5 I

P C 7 I n t e r r u p t

R e q u e s t F l a g P C 7 F

E P C 7 I

S P I / I C I n t e r r u p t

R e q u e s t F l a g S I M F

E S I M

E x t e r n a l P e r i p h e r a l I n t e r r u p t

R e q u e s t F l a g P E F

E P I

T i m e r 2

I n t e r r u p t R e q u e s t F l a g T 2 F

E T 2 I

2

F S K R a w D a t a F a l l i n g E d g e

I n t e r r u p t R e q u e s t F l a g F S K D F

D T M F R e c e i v e r I n t e r r u p t

R e q u e s t F l a g D T M F F

E F S K D I

E D T M F I

F S K P a c k e t D a t a I n t e r r u p t

R e q u e s t F l a g F S K F

F M S K

R i n g o r L i n e R e v e r s a l D e t e c t

I n t e r r u p t R e q u e s t F l a g R D E T F

R M S K

C a r r i e r D e t e c t I n t e r r u p t

R e q u e s t F l a g C D E T F

C M S K

N o t e t h a t : I f t h e E F S K D I i s e n a b l e d , t h a t w i l l d i s a b l e F M S K , R M S K a n d C M S K , t h e s e t h r e e i n t e r r u p t s . T h e d e s i g n e r s h o u l d t a k e c a r e t h i s l i m i t a t i o n .

Interrupt Structure

Programming Considerations

By disabling the interrupt enable bits, a requested inter-

rupt can be prevented from being serviced, however,

once an interrupt request flag is set, it will remain in this

condition in the INTC register until the corresponding in-

terrupt is serviced or until the request flag is cleared by a

software instruction.

It is recommended that programs do not use the

²CALL

subroutine

² instruction within the interrupt subroutine. In-

terrupts often occur in an unpredictable manner or need

to be serviced immediately in some applications. If only

one stack is left and the interrupt is not well controlled, the

original control sequence will be damaged once a

²CALL

subroutine

² is executed in the interrupt subroutine.

All of these interrupts have the capability of waking up

the processor when in the Power Down Mode. Only the

Program Counter is pushed onto the stack. If the con-

tents of the register or status register are altered by the

interrupt service program, which may corrupt the de-

sired control sequence, then the contents should be

saved in advance.