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3.1. Guideline: VREF Sources and VREF Pins
3.2. Guideline: Observe Device Absolute Maximum Rating for 3.0 V Interfacing
3.3. Guideline: Voltage-Referenced and Non-Voltage Referenced I/O Standards
3.4. Guideline: Do Not Drive I/O Pins During Power Sequencing
3.5. Guideline: Stratix® 10 I/O Buffer During Power Up, Configuration, and Power Down
3.6. Guideline: Maximum DC Current Restrictions
3.7. Guideline: Use Only One Voltage for All 3 V I/O Banks
3.8. Guideline: I/O Standards Limitation for Stratix® 10 TX 400
3.9. Guideline: I/O Standards Limitation for Stratix® 10 GX 400 and SX 400
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4.1.2. GPIO Intel® FPGA IP Data Paths
Figure 25. High-Level View of Single-Ended GPIO
Data Path | Register Mode | |||
---|---|---|---|---|
Bypass | Simple Register | DDR I/O | ||
Full-Rate | Half-Rate | |||
Input | Data goes from the delay element to the core, bypassing all double data rate I/Os (DDIOs). | The full-rate DDIO operates as a simple register, bypassing half-rate DDIOs. The Fitter chooses whether to pack the register in the I/O or implement the register in the core, depending on the area and timing trade-offs. | The full-rate DDIO operates as a regular DDIO, bypassing the half-rate DDIOs. | The full-rate DDIO operates as a regular DDIO. The half-rate DDIOs convert full-rate data to half-rate data. |
Output | Data goes from the core straight to the delay element, bypassing all DDIOs. | The full-rate DDIO operates as a simple register, bypassing half-rate DDIOs. The Fitter chooses whether to pack the register in the I/O or implement the register in the core, depending on the area and timing trade-offs. | The full-rate DDIO operates as a regular DDIO, bypassing the half-rate DDIOs. | The full-rate DDIO operates as a regular DDIO. The half-rate DDIOs convert full-rate data to half-rate data. |
Bidirectional | The output buffer drives both an output pin and an input buffer. | The full-rate DDIO operates as a simple register. The output buffer drives both an output pin and an input buffer. | The full-rate DDIO operates as a regular DDIO. The output buffer drives both an output pin and an input buffer. The input buffer drives a set of three flip-flops. | The full-rate DDIO operates as a regular DDIO. The half-rate DDIOs convert full-rate data to half-rate. The output buffer drives both an output pin and an input buffer. The input buffer drives a set of three flip-flops. |
If you use asynchronous clear and preset signals, all DDIOs share these same signals.
Half-rate and full-rate DDIOs connect to separate clocks. When you use half-rate and full-rate DDIOs, the full-rate clock must run at twice the half-rate frequency. You can use different phase relationships to meet timing requirements.