Octal E1 Line Interface — LXT381

Datasheet

21

3.3.1

Boundary Scan Register (BSR)

The BSR is a shift register that provides access to all the digital I/O pins. The BSR is used to apply

and read test patterns to/from the board. Each pin is associated with a scan cell in the BSR register.

Bidirectional pins or tristatable pins require more than one position in the register. Table 4 shows

the BSR scan cells and their functions. Data into the BSR is shifted in LSB first

.

Table 4.

Boundary Scan Register (BSR)

Bit #

Pin

Signal

I/O

Type

Bit

Symbol

Comments

0LOOP0

I/O

PDO0

1

LOOP0

I/O

PADD0

2LOOP1

I/O

PDO1

3LOOP1

I/O

PADI1

4LOOP2

I/O

PDO2

5LOOP2

I/O

PADI2

6LOOP3

I/O

PDO3

7LOOP3

I/O

PADI3

8LOOP4

I/O

PDO4

9LOOP4

I/O

PADI4

10

LOOP5

I/O

PDO5

11

LOOP5

I/O

PADI5

12

LOOP6

I/O

PDO6

13

LOOP6

I/O

PADI6

14

LOOP7

I/O

PDO7

15

LOOP7

I/O

PADI7

16

N/A

-

PDOEN

PDOEN controls the LOOP0 through LOOP7 pins.

Setting PDOEN to “1” configures the pins as outputs. The output value to

the pin is set in PDO[0..7].

Setting PDOEN to “0” tristates all the pins. The input value to the pins can

be read in PADD[0.7].

17

TCLK1

I

TCLK1

18

TPOS1

I

TPOS1

19

TNEG1

I

TNEG1

20

RCLK1

O

RCLK1

21

RPOS1

O

RPOS1

22

RNEG1

O

RNEG1

23

N/A

-

HIZB1

HIZB1 controls the RPOS1, RNEG1 and RCLK1 pins. Setting HIZB1 to

“1” enables output on the pins. Setting HIZB1 to “0” tristates the pins.

24

LOS1

O

LOS1

25

TCLK0

I

TCLK0

26

TPOS0

I

TPOS0

27

TNEG0

I

TNEG0