SMSC UG - EVB-20022

Page 5

Rev. 1/5/00

4.

At the next menu type “a”. The screen will have a list of registers and their values. Got to the config

register, one from the bottom. Change the third bit from the right (BKPLNE) from a “0” to a “1”. Exit to

the previous menu.

5.

Select “b” from the menu. Change the register labeled IOH_1. The left most bit (P1MODE) needs to be

change from a “0” to a “1”. Exit back to the main menu.

6.

At the main menu, select option “D” to save all of the changes that have been made to the registers.

7.

To start the test, select “I” from the main menu, Ping-Pong. This is only to be done on one machine.

8.

A menu will come up asking how many other nodes, and the node ID of the other nodes. Make sure the

nodes IDs are not the same. If the test is running correctly, “T” and “R” should alternate scrolling down

the screen on both machines .

Coaxial Interface

The coaxial interface uses a standard 93-ohm BNC connector, the same as a 50-ohm BNC, and requires a RG-62

type cable with 93-ohm terminations. The following guidelines for bus topology should be used for coaxial interface:

1.

Max. distance(without repeaters).............1000’

2.

Min. distance between nodes ...................3’

3.

Max. number of nodes per segment ........8 (i.e. no repeaters)

4.

Max number of nodes with repeaters ......255

Operation is valid only at 2.5 Mbps and uses the SMSC HYC9088 hybrid (U15).

To setup the board for coaxial interface, with the use of SMSC DEMOAT software, perform the following steps:

1.

Install both jumpers horizontally at JP11 (Differential paired data)

2.

Install the jumper horizontally at JP12 (Coax filter)

3.

Set jumper blocks JP13 and JP5 both to D (Transmit data and receive data)

4.

Set I/O board address as specified in I/O address selection in User Guide (e.g. 02E0)

5.

Set Node ID as specified in Node ID selection in User Guide

Note:

Make sure JP6, JP8, JP9, and JP10 are left unconnected.

Note:

If socketed COM20022 (SKT1) is being utilized, U8 (alternate COM20022 device) must not be mounted on

evaluation board.

Figure 1

For proper coaxial operation, installed jumpers denoted in black.

JP1

2

1

1

1

1

1

JP

JP

8

JP

9

JP1

0

JP1

1

1

A

B

C

D

1

A

B

C

D

1

1

`

JP1

JP

U1

U1

2

U1

5

U1

3

T1

JP

7

S1

J1

J2

C

O

A

LE

D

SKT

1

U8

JP

S2

S3

10

11

15

3

4

5

7

9

12

7