ECE448 Lecture15 External SRAM

ECE 448 – FPGA and ASIC Design with VHDL

Lecture 15

External SRAM

2ECE 448 – FPGA and ASIC Design with VHDL

Required reading

• P. Chu, FPGA Prototyping by VHDL Examples

Chapter 10, External SRAM

3

Block diagram of a typical SRAM

ECE 448 – FPGA and ASIC Design with VHDL

4

SRAM Functional Table

ECE 448 – FPGA and ASIC Design with VHDL

5

SRAM Simplified Functional Table

ECE 448 – FPGA and ASIC Design with VHDL

6

Timing diagram of an address-controlled read cycle

ECE 448 – FPGA and ASIC Design with VHDL

7

Timing diagram of an output_enable-controlled read cycle

ECE 448 – FPGA and ASIC Design with VHDL

8

SRAM Timing Parameters (in ns)

ECE 448 – FPGA and ASIC Design with VHDL

9

Timing diagram of write cycle

ECE 448 – FPGA and ASIC Design with VHDL

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SRAM Timing Parameters (in ns)

ECE 448 – FPGA and ASIC Design with VHDL

11

Role of a memory controller

ECE 448 – FPGA and ASIC Design with VHDL

12

Block diagram of a memory controller

ECE 448 – FPGA and ASIC Design with VHDL

13

ASM chart of a safe SRAM

controller

ECE 448 – FPGA and ASIC Design with VHDL

14

ASM chart of a testing

circuit

ECE 448 – FPGA and ASIC Design with VHDL

15

ASM chart of an alternative

SRAM controller: design I

ECE 448 – FPGA and ASIC Design with VHDL

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ASM chart of an alternative

SRAM controller: design II

ECE 448 – FPGA and ASIC Design with VHDL

17ECE 448 – FPGA and ASIC Design with VHDL

ASM chart of an alternative

SRAM controller: design III

18

Generating a half cycle with DDR

ECE 448 – FPGA and ASIC Design with VHDL