1.5. Simulation Versus Hardware Implementation
For external memory interface simulation, you can select either skip calibration or full calibration on the Diagnostics tab during IP generation.
EMIF Simulation Models
This table compares the characteristics of the skip calibration and full calibration models.
Skip Calibration | Full Calibration |
---|---|
System-level simulation focusing on user logic. | Memory interface simulation focusing on calibration. |
Details of calibration are not captured. | Captures all stages of calibration. |
Has ability to store and retrieve data. | Includes leveling, per-bit deskew, etc. |
Represents accurate efficiency. | |
Does not consider board skew. |
RTL Simulation Versus Hardware Implementation
This table highlights key differences between EMIF simulation and hardware implementation.
RTL Simulation | Hardware Implementation |
---|---|
Nios® initialization and calibration code execute in parallel. | Nios® initialization and calibration code execute sequentially. |
Interfaces assert cal_done signal signal simultaneously in simulation. | Fitter operations determine the order of calibration, and interfaces do not assert cal_done simultaneously. |
You should run RTL simulations based on traffic patterns for your design's application. Note that RTL simulation does not model PCB trace delays which may cause a discrepancy in latency between RTL simulation and hardware implementation.