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Method for a training algorithm for the maximum data transfer after the STPA signal is deasserted

IP.com Disclosure Number: IPCOM000125742D
Publication Date: 2005-Jun-15
Document File: 4 page(s) / 70K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a training algorithm for the maximum data transfer after the selected transmit packet available (STPA) signal is deasserted. Benefits include improved functionality, improved performance, and improved cost effectiveness

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Method for a training algorithm for the maximum data transfer after the STPA signal is deasserted

Disclosed is a method for a training algorithm for the maximum data transfer after the selected transmit packet available (STPA) signal is deasserted. Benefits include improved functionality, improved performance, and improved cost effectiveness.

Background

              POS-PHY™ level 2 standard PMC-971147 “SATURN® compatible Packet Over SONET Interface Specification for Physical Layer Devices, Issue 5” was published December 1998. POS-PHY Level 3™ was standardized by the ATM Forum Technical Committee in March 2000, “Frame-based ATM Interface Level 3,” AF-PHY-0143.000. POS-PHY and POS-PHY Level 3 are trademarks of PMC-Sierra, Inc. SATURN is a registered trademark of PMC-Sierra, Inc.

              Conventionally, firmware is used to set the STPA first-in, first-out buffer (FIFO) trigger levels to prevent a FIFO overflow due to the delayed response time of the TX Link. When a new physical (PHY) device or a link with a different response time is used, the firmware is required to reprogram a different FIFO maximum threshold (watermark) setting and a different number of cycles allowed by the link to transmit data after STPA is deasserted.

General description

              The disclosed method includes a training algorithm to automatically search and configure the STPA and direct transmit packet available (DTPA) response values required for POS-PHY level 2 and level 3 compliant interfaces.

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to training and configuring POS-PHY level 2 and level 3 compliant interfaces
•             Improved performance due to automatically providing maximum data transfer

•             Improved cost effectiveness due to eliminating the requirement for firmware reprogramming when transmit devices are changed

Detailed description

              The disclosed method trains the POS-PHY level 2 and level 3 compliant interfaces and automatically configures the values required for data transfer. Some signals are optional and the TSX and RSX are only used in level 3 (see Figure 1).

              On the TX Link side, the STPA signal is asserted by the TX PHY side when the selected port is able to receive a packet transfer. When the STPA signal is deasserted (driven low), the TX Link side must deassert the TENB signal (driven high) a programmed number of cycles after STPA is deasserted (driven low) or a first-in, first-out buffer (FIFO) overflow can occur. This value is programmable to enable various response times due to pipeline delays and or in-flight delays associated with different link and physical integrated circuits. These programmable values are typically set by firmware and the TX Link and TX PHY sides must match.

              The disclosed method eliminates using programmable TX Link cycles by implementing a training cycle to identify the required cycles automatica...