ST72324BJ2 datasheet(41/188 Pages) STMICROELECTRONICS

41 / 188 page

ST72324B

Interrupts

41/188

7.5.2

Interrupt software priority registers (ISPRx)

These four registers contain the interrupt software priority of each interrupt vector.

●

Each interrupt vector (except reset and TRAP) has corresponding bits in these

registers where its own software priority is stored. This correspondence is shown in the

following Table 16.

●

Each I1_x and I0_x bit value in the ISPRx registers has the same meaning as the I1

and I0 bits in the CC register.

●

Level 0 cannot be written (I1_x = 1, I0_x = 0). In this case, the previously stored value

is kept (for example, previous value = CFh, write = 64h, result = 44h).

The reset, and TRAP vectors have no software priorities. When one is serviced, the I1 and

I0 bits of the CC register are both set.

Caution:

If the I1_x and I0_x bits are modified while the interrupt x is executed the following behavior

has to be considered: If the interrupt x is still pending (new interrupt or flag not cleared) and

the new software priority is higher than the previous one, the interrupt x is re-entered.

Otherwise, the software priority stays unchanged up to the next interrupt request (after the

IRET of the interrupt x).

ISPRx

Reset value: 1111 1111 (FFh)

7654321

ISPR0

I1_3

I0_3

I1_2

I0_2

I1_1

I0_1

I1_0

I0_0

ISPR1

I1_7

I0_7

I1_6

I0_6

I1_5

I0_5

I1_4

I0_4

ISPR2

I1_11

I0_11

I1_10

I0_10

I1_9

I0_9

I1_8

I0_8

R/WR/W

R/W

ISPR3

1111

I1_13

I0_13

I1_12

I0_12

R/W

Table 16.

ISPRx interrupt vector correspondence

Vector address

ISPRx bits

FFFBh-FFFAh

I1_0 and I0_0 bits

FFF9h-FFF8h

I1_1 and I0_1 bits

...

FFE1h-FFE0h

I1_13 and I0_13 bits

Table 17.

Dedicated interrupt instruction set(1)

Instruction

New description

Function/example

HALT

Entering HALT mode

IRET

Interrupt routine return

POP CC, A, X, PC

JRM

Jump if I1:0=11 (level 3)

I1:0=11 ?

JRNM

Jump if I1:0<>11

I1:0<>11 ?

ST72324BJ2 Datasheet(PDF) 41 Page - STMicroelectronics

ST72324BJ2 Datasheet(HTML) 41 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL