ST7LITE1XB datasheet(38/157 Pages) STMICROELECTRONICS

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ST7LITE1xB

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INTERRUPTS (Cont’d)

EXTERNAL INTERRUPT CONTROL REGISTER

(EICR)

Read/Write

Reset Value: 0000 0000 (00h)

Bits 7:6 = IS3[1:0] ei3 sensitivity

These bits define the interrupt sensitivity for ei3

(Port B0) according to Table 6.

Bits 5:4 = IS2[1:0] ei2 sensitivity

These bits define the interrupt sensitivity for ei2

(Port B3) according to Table 6.

Bits 3:2 = IS1[1:0] ei1 sensitivity

These bits define the interrupt sensitivity for ei1

(Port A7) according to Table 6.

Bits 1:0 = IS0[1:0] ei0 sensitivity

These bits define the interrupt sensitivity for ei0

(Port A0) according to Table 6.

Notes:

1. These 8 bits can be written only when the I bit in

the CC register is set.

2. Changing the sensitivity of a particular external

interrupt clears this pending interrupt. This can be

used to clear unwanted pending interrupts. Refer

section

“External

Interrupt

Function”

page 48.

Table 6. Interrupt Sensitivity Bits

EXTERNAL INTERRUPT SELECTION REGIS-

TER (EISR)

Read/Write

Reset Value: 0000 1100 (0Ch)

Bits 7:6 = ei3[1:0] ei3 pin selection

These bits are written by software. They select the

Port B I/O pin used for the ei3 external interrupt ac-

cording to the table below.

External Interrupt I/O pin selection

Note:

1. Reset State

Bits 5:4 = ei2[1:0] ei2 pin selection

These bits are written by software. They select the

Port B I/O pin used for the ei2 external interrupt ac-

cording to the table below.

External Interrupt I/O pin selection

Notes:

1. Reset State

2. PB4 cannot be used as an external interrupt in

HALT mode.

IS31

IS30

IS21

IS20

IS11

IS10

IS01

IS00

ISx1 ISx0

External Interrupt Sensitivity

Falling edge & low level

Rising edge only

Falling edge only

Rising and falling edge

ei31

ei30

ei21

ei20

ei11

ei10

ei01

ei00

ei31

ei30

I/O Pin

PB0 1)

PB1

PB2

ei21

ei20

I/O Pin

PB3 1)

PB4 2)

PB5

PB6

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