8 serial bridge – Cirrus Logic CobraNet User Manual

Page 86

DS651PM25

CobraNet Programmer’s Reference
Management Interface Variable Reference

6.4.8 Serial Bridge

Name

serialFormat

Description

This variable is used to enable or disable the Serial Communications Interface (a.k.a SCI or Serial
Bridge) and to set the data format for both transmit and receive directions. Format may only be
changed while the SCI is disabled (LS bit = 0). It is recommended to set

serialFormat to 0, wait at

least 100ms then set

serialFormat to the desired value with the enable bit set. The SCI can take up

to 100ms to recognize a change.This procedure insures that the change is recognized and the port
is properly configured. The following values may be OR’d together:
0x01 - Enable serial bridging. TXD pin is tri-stated when disabled.
0x02 - Use nine-bit data format. The 9th data bit is bridged over the Ethernet along with the
standard 8 data bits. 9 bit format is appropriate for the following standard serial data formats: N,9,1
E,8,1 O,8,1 M,8,1 S,8,1 N,7,2. The 8 bit data format supports the following standard serial data
formats: N,8,1 E,7,1 O,7,1 M,7,1 S,7,1. If the 8th or 9th bit is used as a parity bit, it is simply bridged
across the network and must be generated and/or checked by the device connected to the bridge
interface.

CS4961xx- and CS1810xx-based hardware does not support 9-bit format; this bit is

ignored.
0x04 - Use SCI_SCLK to control transmit enable for multi-drop (RS485) operation. SCI_SCLK is an
active high signal; transmitter should be enabled when SCI_SCLK is high.
CS4961xx and CS1810xx firmware does not currently support tri-state control format; this bit is
ignored.
0x08 - Enable local loopback. This feature is intended primarily for factory test. SCI bridging must
also be enabled for loopback to operate. When loopback is enabled, received characters are
directed to the SCI transmitter instead of to the network.

serialRxMAC should be set to

00:00:00:00:00:00 to avoid transmitter contention when loopback is enabled.
0x10 - Accept properly unicast addressed data in addition to data addressed in accordance to
serialRxMAC setting.

Host Address

0x24000

SNMP Object ID

1.3.6.1.4.1.2680.1.1.10.1.1

Type

Integer

Attributes

Read/write - Persistent

Default Value

Implemented Version

2.4.7. Available via SNMP in 2.6.4. Accept unicast (0x10 bit) implemented in 2.8.8.

Name

serialBaud

Description

Baud rate for transmission and reception. The baud rate is specified in bits per second. The
minimum baud rate is 600 baud. Maximum baud rate is 57,600. CS4961xx- and CS1810xx-based
interfaces will support baud rates up to 115,200

Host Address

0x24001