Double Data Rate I/O (ALTDDIO_IN, ALTDDIO_OUT, and ALTDDIO_BIDIR) IP Cores User Guide

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ID 683148
Date 6/19/2017
Public
Document Table of Contents
Document Table of Contents
1. Double Data Rate I/O (ALTDDIO_IN, ALTDDIO_OUT, and ALTDDIO_BIDIR) IP Cores User Guide
1. Double Data Rate I/O (ALTDDIO_IN, ALTDDIO_OUT, and ALTDDIO_BIDIR) IP Cores User Guide
1.1. ALTDDIO Features 1.2. ALTDDIO Common Applications 1.3. ALTDDIO Resource Utilization and Performance 1.4. ALTDDIO Parameter Settings 1.5. ALTDDIO Functional Description 1.6. Design Example: 8-Bit DDR Divider Using ALTDDIO_BIDIR 1.7. ALTDDIO_IN IP Core Signals 1.8. ALTDDIO_OUT IP Core Signals 1.9. ALTDDIO_BIDIR IP Core Signals 1.10. Verilog HDL Prototype 1.11. VHDL Component Declaration 1.12. VHDL LIBRARY-USE Declaration 1.13. Double Data Rate I/O (ALTDDIO_IN, ALTDDIO_OUT, and ALTDDIO_BIDIR) IP Cores User Guide Archives 1.14. Document Revision History
1.2. ALTDDIO Common Applications
1.2.1. DDR SDRAM, DDR2 SDRAM and RLDRAM II Memory 1.2.2. QDR SRAM and QDRII SRAM Memory Interfaces 1.2.3. High-Speed Interface Applications
1.5. ALTDDIO Functional Description
1.5.1. DDR Device Configuration 1.5.2. DDR I/O Timing
1.5.1. DDR Device Configuration
1.5.1.1. Input Configuration 1.5.1.2. Output Configuration 1.5.1.3. Bidirectional Configuration
1.6. Design Example: 8-Bit DDR Divider Using ALTDDIO_BIDIR
1.6.1. Generate a Divider Using ALTDDIO_BIDIR 1.6.2. Create a Divider 1.6.3. Implement the Divider Design 1.6.4. Functional Results—Simulate the Divider Design in the ModelSim* - Intel® FPGA Edition Software
1.6.1. Generate a Divider Using ALTDDIO_BIDIR
1.6.1.1. Create the ALTDDIO_BIDIR IP Core 1.6.1.2. Create the LPM_DIVIDE IP core
1. Double Data Rate I/O (ALTDDIO_IN, ALTDDIO_OUT, and ALTDDIO_BIDIR) IP Cores User Guide

1.5.1.2. Output Configuration

The dedicated output registers for Stratix® series and APEX™ II devices are labeled AO and BO. These positive-edge triggered registers and a multiplexer are used to implement the output path for DDR I/O.
Figure 3. Output DDR I/O Path Configuration for Stratix Series and APEX II DevicesThis figure shows the IOE configuration for DDR outputs in Stratix® series and APEX™ II devices.

On the positive edge of the clock, a high data bit and a low data bit are captured in registers AO and BO. The outputs of these two registers are fed to the input of a 2-to-1 multiplexer, which uses the output register clock as its control signal. A high clock selects the data in register BO, and a low level of the clock selects the data in register AO. This process doubles the data at the I/O pin.

Figure 4. Stratix IOE in DDR Output I/O ConfigurationThis figure shows the IOE configuration for DDR outputs in Stratix® series devices
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