tdat04622 ETC-unknow, tdat04622 Datasheet - Page 14

• Manufacturer Part Number: tdat04622
• Description: Tdat Sonet/sdh 155/622/2488 Mbits/s Data Interfaces
• Manufacturer: ETC-unknow

for Version 1 and 1A of the Device
Data Engine (DE)
DE10. Excessive HDLC Flag Characters
The following three issues refer to HDLC flag character (0x7E) problems in the data engine:
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Workaround
Set the UTOPIA egress low watermark value in the UTOPIA egress provisioning registers (0x0212, 0x0216,
0x021A, 0x021E) to either 1 or 2 to prevent excessive 0x7Es from being inserted between packets.
Corrective Action
This condition will be addressed in future versions of the device.
UTOPIA (UT)
UT1. Polling in Multidevice MPHY Mode
When the TDAT042G5 is polled and responds, the data bus becomes enabled. In a multidevice MPHY configura-
tion, if the data bus is active from a different PHY device, response to a poll from the device will corrupt a data
transfer already in progress. TDAT042G5 MPHY always functions without data corruption in a single-device
(slave), multiple-channel configuration (point-to-point).
Workaround
No workaround is available for this condition.
Corrective Action
This condition will be addressed in future versions of the device.
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An excessive number of HDLC flag characters (0x7Es) may be inserted between packets on the transmit side if
the UTOPIA low watermark value is set above 2. This will have the effect of reducing the bandwidth of the device.
The data engine operates on 32-bit boundaries. Egress packets that are not multiples of four will be filled with
0x7Es.
Egress packets consisting of all 0x7Es as data will be corrupted.
(continued)
Agere Systems Inc.
May 2001