COM20019 Datasheet, PDF(34/81 Page) SMSC Corporation – Low Cost ARCNET (ANSI 878.1) Controller with 2K x 8 On-Board RAM

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COM20019 Datasheet, PDF (34/81 Pages) SMSC Corporation – Low Cost ARCNET (ANSI 878.1) Controller with 2K x 8 On-Board RAM

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4,3 Extended

Timeout 1,2

2 Backplane

1,0 Sub Address 1,0

Table 10 - Configuration Register

ET1, ET2

These bits allow the network to operate over longer distances

than the default maximum 32 miles by controlling the

Response, Idle, and Reconfiguration Times. All nodes should

be configured with the same timeout values for proper

network operation. For the COM20019 with a 20 MHz crystal

oscillator, the bit combinations follow:

BACK-

PLANE

SUBAD

1,0

Response Idle Time Reconfig

ET2

ET1 Time (mS) (mS) Time (S)

9.548

10.496

13.44

4.774

5.248

13.44

2.387

2.624

13.44

0.597

0.656

6.72

Note: These values are for 312.5 Kbps and

RCNTMR[1,0]=00. Reconfiguration time is changed by the

RCNTMR1 and RCNTMR0 bits.

A logic "1" on this bit puts the device into Backplane Mode

signaling which is used for Open Drain and Differential Driver

interfaces. This bit must be set to â1â at the COM20019.

These bits determine which register at address 07 may be

accessed. The combinations are as follows:

SUBAD1

SUBAD0 Register

0 Tentative ID

1 Node ID

0 Setup 1

1 Next ID