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Table Of Contents

Contents
- Figures
- Tables
- Revision History
Preface
- P.1 About the EP93xx User’s Guide
- P.2 Related Documents from Cirrus Logic
- P.3 Reference Documents
- P.4 Notational Conventions
- P.5 Register Example
Introduction
- 1.1 Introduction
- 1.2 EP93xx Features
- 1.3 EP93xx Processor Applications
- 1.4 EP93xx Processor Highlights
ARM920T Core and Advanced High-Speed Bus (AHB)
- 2.1 Introduction
- 2.2 Overview: ARM920T Core
- 2.3 AHB Decoder
MaverickCrunch Co-Processor
- 3.1 Introduction
- 3.2 Programming Examples
  - 3.2.1 Example 1
  - 3.2.2 Example 2
    - 3.2.2.1 C Code
    - 3.2.2.2 MaverickCrunch Assembly Language Instructions
- 3.3 DSPSC Register
- 3.4 ARM Co-Processor Instruction Format
- 3.5 Instruction Set for the MaverickCrunch Co-Processor
Boot ROM
- 4.1 Introduction
  - 4.1.1 Boot ROM Hardware Operational Overview
    - 4.1.1.1 Memory Map
  - 4.1.2 Boot ROM Software Operational Overview
- 4.2 Boot Options
System Controller
- 5.1 Introduction
- 5.2 Registers
Vectored Interrupt Controller
- 6.1 Introduction
- 6.2 Registers
Raster Engine With Analog/LCD Integrated Timing and Interface
- 7.1 Introduction
- 7.2 Features
- 7.3 Raster Engine Features Overview
- 7.4 Functional Details
- 7.5 Registers
Graphics Accelerator
- 8.1 Overview
- 8.2 Block Processing Modes
- 8.3 Line Draws
  - 8.3.1 Breshenham Line Draws
  - 8.3.2 Pixel Step Line Draws
- 8.4 Memory Organization for Graphics Accelerator
- 8.5 Register Programming
  - 8.5.1 Word Count
    - 8.5.1.1 Example: 8 BPP mode
    - 8.5.1.2 Example: 24 BPP (packed) mode
  - 8.5.2 Pixel End and Start
- 8.6 Register Usage
- 8.7 Registers
1/10/100 Mbps Ethernet LAN Controller
- 9.1 Introduction
- 9.2 Descriptor Processor
- 9.3 Registers
DMA Controller
- 10.1 Introduction
- 10.2 Registers
  - 10.2.1 DMA Controller Memory Map
  - 10.2.2 Internal M2P/P2M Channel Register Map
Universal Serial Bus Host Controller
- 11.1 Introduction
  - 11.1.1 Features
- 11.2 Overview
- 11.3 Registers
Static Memory Controller
- 12.1 Introduction
- 12.2 Static Memory Controller Operation
- 12.3 PCMCIA Interface (EP9315 Processor Only)
- 12.4 PC Card Memory-Mode Enable Signals
- 12.5 PC Card Memory Mapping
- 12.6 Registers
  - 12.6.1 Bank Configuration Registers
  - 12.6.2 PCMCIA Configuration Registers (EP9315 Processor Only)
SDRAM, SyncROM, and SyncFLASH Controller
- 13.1 Introduction
- 13.2 Booting from SyncROM or SyncFLASH
- 13.3 Address Pin Usage
- 13.4 SDRAM Initialization
- 13.5 Programming Mode Register: SDRAM Or SyncROM Device
- 13.6 SDRAM Self Refresh
  - 13.6.1 Entering Self Refresh Mode
  - 13.6.2 Exiting Self Refresh Mode
- 13.7 Programming Registers: SyncFLASH Device
- 13.8 External Synchronous Memory System
  - 13.8.1 Chip Select SDCSN[3:0] Decoding
  - 13.8.2 Address/Data/Control Required by Memory System
- 13.9 Registers
UART1 With HDLC and Modem Control Signals
- 14.1 Introduction
- 14.2 UART Overview
- 14.3 Modem
- 14.4 HDLC
- 14.5 UART1 Package Dependency
  - 14.5.1 Clocking Requirements
  - 14.5.2 Bus Bandwidth Requirements
- 14.1 Registers
UART2
- 15.1 Introduction
- 15.2 IrDA SIR Block
- 15.3 UART2 Package Dependency
  - 15.3.1 Clocking Requirements
  - 15.3.2 Bus Bandwidth Requirements
- 15.4 Registers
UART3 With HDLC Encoder
- 16.1 Introduction
- 16.2 Implementation Details
- 16.3 Registers
IrDA
- 17.1 Introduction
- 17.2 IrDA Interfaces
- 17.3 Shared IrDA Interface Feature
- 17.4 Medium IrDA Specific Features
  - 17.4.1 Introduction
    - 17.4.1.1 Bit Encoding
    - 17.4.1.2 Frame Format
  - 17.4.2 Functional Description
- 17.5 Fast IrDA Specific Features
- 17.6 Registers
Timers
- 18.1 Introduction
- 18.2 Registers
Watchdog Timer
- 19.1 Introduction
- 19.1 Registers
Real Time Clock With Software Trim
- 20.1 Introduction
  - 20.1.1 Software Trim
  - 20.1.2 Reset Control
- 20.1 Registers
I2S Controller
- 21.1 Introduction
- 21.2 I2S Transmitter Channel Overview
- 21.3 I2S Receiver Channel Overview
  - 21.3.1 Receiver FIFO’s
- 21.4 I2S Master Clock Generation
- 21.5 I2S Bit Clock Rate Generation
  - 21.5.1 Example of the Bit Clock Generation.
  - 21.5.2 Example of Right Justified LRCK format
- 21.6 Interrupts
- 21.7 Registers
AC’97 Controller
- 22.1 Introduction
- 22.2 Interrupts
  - 22.2.1 Channel Interrupts
  - 22.2.2 Global Interrupts
- 22.3 System Loopback Testing
- 22.4 Registers
Synchronous Serial Port
- 23.1 Introduction
- 23.2 Features
- 23.3 SSP Functionality
- 23.4 SSP Pin Multiplex
- 23.5 Configuring the SSP
- 23.6 Registers
Pulse Width Modulator
- 24.1 Introduction
- 24.2 Theory of Operation
  - 24.2.1 PWM Programming Examples
  - 24.2.2 Programming Rules
- 24.3 Registers
Analog Touch Screen Interface
- 25.1 Introduction
- 25.2 Touch Screen Controller Operation
- 25.3 Registers
Keypad Interface
- 26.1 Introduction
- 26.2 Theory of Operation
- 26.3 Registers
IDE Interface
- 27.1 Introduction
- 27.2 Theory of Operation
- 27.3 Registers
GPIO Interface
- 28.1 Introduction
- 28.2 Registers
Security
- 29.1 Introduction
- 29.2 Features
- 29.3 Contact Information
- 29.4 Registers
Glossary
EP93XX Register List

DS785UM1 9-7

1/10/100 Mbps Ethernet LAN Controller

EP93xx User’s Guide

9.1.4 Transmit Back-Off

Refer to Figure 9-3. Once transmission is started, either the transmission is completed, or

there is a collision. There are two kinds of collision: normal collision (one that occurs within

the first 512 bits of the packet) and late collision (one that occurs after the first 512 bits). In

either collision type, the MAC engine always sends a 32 bit jam sequence, and stops

transmission.

After a normal collision and the jam, transmission is stopped, or “backed-off”. The MAC

attempts transmission again according to one of two algorithms. The ISO/IEC standard

algorithm or a modified back-off algorithm may be used, and the host chooses which

algorithm through the ModBackoffE control bit (TXCtl). The standard algorithm from ISO/IEC

paragraph 4.2.3.2.5 is called the “truncated binary exponential backoff” and is shown below:

0 <= r <= 2

where r is a random integer for the number of slot times the MAC waits before attempting

another transmission, and a slot time is time of 512 bits (51.2 μsec), k = minimum (n,10), and

n is the nth retransmission attempt. The modified back-off algorithm uses delays longer than

the ISO/IEC standard after each of the first three transmit collisions as shown below:

0 <= r <= 2

where k = minimum (n,10), but not less than 3, and n is the nth retransmission attempt

The advantage of the modified algorithm over the standard algorithm is that the modification

reduces the possibility of multiple collisions on any transmission attempt. The disadvantage is

that the modification extends the maximum time needed to acquire access to the medium.

The host may choose to disable the back-off algorithm altogether. This is done through the

control bit DisableBackoff (TestCtl). When set, the MAC transmitter waits for the Inter Frame

Gap time before starting transmission. There is no back-off algorithm employed. When clear,

the MAC uses either the standard or the modified algorithm.

9.1.4.1 Transmission

After the transmission has passed the time for a normal collision (512 bits), then transmission

is either completed, or aborted due to a late collision. For a late collision, the transmitter

sends the 32 bit jam sequence, but does not back-off and try again. When a late collision

occurs, Out-of-wdw collision (XStatQ) is set. A late collision is not retried, because the first 64

bytes of the FIFO are freed after the normal collision window, and will likely be refilled by a

following packet. Driver intervention is needed to reconstruct the FIFO data.

9.1.4.2 The FCS Field

If InhibitCRC (Transmit Descriptor) is clear, the MAC automatically appends the standard 32

bit FCS to the end of the frame. The MAC tests the last 32 bits received against the standard

CRC computation. If received in error, CRCerror (RStatQ) is set. If CRCerroriE (Interrupt

Enable) is set, there is an interrupt associated with CRCerror. The standard CRC conforms to

ISO/IEC 8802-3 section 3.2.8. The polynomial for the CRC is:

G(x) = x

+ x

+ x + 1