Altera RAM-Based Shift Register Manuel d'utilisateur télécharger pdf (Page 16)

2–10 Chapter 2: Getting Started

Design Example: Shift Register with Taps

RAM-Based Shift Register (ALTSHIFT_TAPS) Megafunction User Guide May 2013 Altera Corporation

View the simulation results in the Wave window. Figure 2–7 shows the expected

simulation results in the ModelSim-Altera software.

Understanding the Simulation Results

In this example, you configured the shift register to have the following properties:

■ 8-bit data width

■ Distance between taps (taps length) equals to 3

■ Number of taps equals to 4

■ Created groups for each tap output

■ Created a clock-enable signal and an asynchronous-clear signal

This example shows how you can tap the 1st-4th-7th-10th data words simultaneously

(followed by the 2nd-5th-8th-11th and 3rd-6th-9th-12th) when all 12 words of data are

shifted into the shift register.

Figure 2–8 shows the shift register chain that is analogous to the configuration you set

in the ALTSHIFT_TAPS megafunction in this example.

The next section uses this shift register chain to explain the shifting operation and the

output operation of the ALTSHIFT_TAPS megafunction.

Figure 2–7. Simulation Waveform for Shift Register with Taps Design Example

Figure 2–8. Shift Register Chain Analogy to the Configured ALTSHIFT_TAPS Megafunction

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 25 26

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Altera RAM-Based Shift Register Manuel d'utilisateur Page 16