GPIO Intel® FPGA IP User Guide: Intel® Arria® 10 and Intel® Cyclone® 10 GX Devices

ID 683136
Date 1/25/2022

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Output and Output Enable Paths

The output delay element sends data to the pad through the output buffer.

Each output path contains two stages of DDIOs, which are half-rate and full-rate.

Figure 4. Simplified View of Single-Ended GPIO Output Path

Figure 5. Output Path Waveform in DDIO Mode with Half-Rate Conversion
Figure 6.  Simplified View of Output Enable Path

The difference between the output path and output enable (OE) path is that the OE path does not contain full-rate DDIO. To support packed-register implementations in the OE path, a simple register operates as full-rate DDIO. For the same reason, only one half-rate DDIO is present.

The OE path operates in the following three fundamental modes:

  • Bypass—the core sends data directly to the delay element, bypassing all DDIOs.
  • Packed Register—bypasses half-rate DDIO.
  • SDR output at half-rate—half-rate DDIOs convert data from full-rate to half-rate.
Note: The GPIO IP core does not support dynamic calibration of bidirectional pins. For applications that require dynamic calibration of bidirectional pins, refer to the related information.