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Ixiasoft
Visible to Intel only — GUID: kla1645671532546
Ixiasoft
8. Programmable I/O Features Description
I/O Features | Description | |
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Programmable Output Slew Rate Control | Each I/O pin contains a slew rate control, allowing you to specify the slew rate on a pin-by-pin basis. The slew rate control affects both the rising and falling edges of the signal. A faster slew rate provides high-speed transitions for high-performance systems while a slower slew rate reduces system noise and crosstalk but adds a nominal delay to the rising and falling edges. |
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Programmable IOE Delay | You can activate the programmable IOE delays to ensure zero hold time, minimize setup time, or increase the clock-to-output time. This feature helps read and write timing margins because it minimizes the uncertainties between signals on the bus. Each pin can have a different input delay from the pin-to-input register or a delay from output register-to-output pin values. This is to ensure that the signals within a bus have the same delay going into or out of the device. |
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Programmable Current Strength | You can assign current strength setting to the single-ended output buffer. For a list of I/O standards that support programmable current strength, refer to the related information. The current strength setting is not supported for:
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Programmable Open-Drain Output | The programmable open-drain output provides a high-impedance state on output when logic to the output buffer is high. If logic to the output buffer is low, the output is low. You can attach several open-drain outputs to a wire. This connection type is like a logical OR function and is commonly called an active-low wired-OR circuit. If at least one of the outputs is in logic 0 state (active), the circuit sinks the current and brings the line to low voltage. You can use open-drain output if you are connecting multiple devices to a bus. For example, you can use the open-drain output for system-level control signals that can be asserted by any device or as an interrupt. |
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Programmable Pull-Up Resistor | Each I/O pin on supported banks provides an optional programmable pull-up resistor during user mode. The pull-up resistor weakly holds the I/O to the I/O bank power supply level. |
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Programmable Pull-Down Resistor | Each I/O pin on supported banks provides an optional programmable pull-down resistor during user mode. The pull-down resistor weakly holds the I/O to the ground level. |
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Programmable Pre-Emphasis | Pre-emphasis momentarily boosts the high-frequency component of the output signal during switching to increase the output slew rate. The amount of pre-emphasis required depends on the attenuation of the high-frequency component along the transmission line. For more information, refer to Programmable Pre-Emphasis. |
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Programmable De-Emphasis | De-emphasis attenuates the I/O signal height when the symbol is longer than the specified duration. You can use de-emphasis to alter the signal amplitude to compensate for signal degradation over long transmission path. For more information, refer to Programmable De-Emphasis. |
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Receiver Equalization Calibration | The FPGAs support two types of receiver equalization calibration:
For more information, refer to: |
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Programmable Differential Output Voltage | The programmable VOD settings allow you to adjust the output eye-opening to optimize the trace length and power consumption. A higher VOD swing improves voltage margins at the receiver end, and a smaller VOD swing reduces power consumption. For more information, refer to Programmable Differential Output Voltage. |
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Schmitt Trigger | The Schmitt Trigger allows input buffers to respond to slow input edge rates with a fast output edge rate. Most importantly, Schmitt Triggers provide hysteresis on the input buffer, preventing slow-rising noisy input signals from ringing or oscillating on the input signal driven into the logic array. This feature provides system noise tolerance on the device inputs but adds a small, nominal input delay. |
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On-Die Termination Impedance | The HPS and SDM input pins support on-die pull-up and pull-down termination. The on-die termination provides impedance matching and termination capabilities. You can enable this feature on input operations to minimize reflections and improve electrical margins. |