lecture 10 xilinx fpga memories part...
TRANSCRIPT
ECE 448 – FPGA and ASIC Design with VHDL
Lecture 10
Xilinx FPGA Memories
Part 1
2 ECE 448 – FPGA and ASIC Design with VHDL
Recommended reading • Spartan-6 FPGA Block RAM Resources: User Guide
Google search: UG383
• Spartan-6 FPGA Configurable Logic Block: User Guide
Google search: UG384
• Xilinx FPGA Embedded Memory Advantages: White Paper
Google search: WP360
• ISE In-Depth Tutorial, Section: Creating a CORE Generator Tool Module
Google search: ISE In-Depth Tutorial
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Memory Types
4
Memory Types
Memory
RAM ROM
Single port Dual port
With asynchronous read
With synchronous read
Memory
Memory
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Memory Types specific to Xilinx FPGAs
Memory
Distributed (MLUT-based)
Block RAM-based (BRAM-based)
Inferred Instantiated
Memory
Manually Using CORE Generator
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FPGA Distributed Memory
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Location of Distributed RAM RAM blocks
Multipliers
Logic blocks
Graphics based on The Design Warrior’s Guide to FPGAs Devices, Tools, and Flows. ISBN 0750676043
Copyright © 2004 Mentor Graphics Corp. (www.mentor.com)
DSP units RAM blocks
Logic resources
(#Logic resources, #Multipliers/DSP units, #RAM_blocks)
Logic resources (CLB slices)
8 ECE 448 – FPGA and ASIC Design with VHDL
Three Different Types of Slices
50% 25% 25%
9
16-bit SR
16 x 1 RAM
4-input LUT
The Design Warrior’s Guide to FPGAs Devices, Tools, and Flows. ISBN 0750676043
Copyright © 2004 Mentor Graphics Corp. (www.mentor.com)
Spartan-6 Multipurpose LUT (MLUT)
64 x 1 ROM
(logic)
64 x 1 RAM
32-bit SR
10 ECE 448 – FPGA and ASIC Design with VHDL
Single-port 64 x 1-bit RAM
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Memories Built of Neighboring MLUTs
ECE 448 – FPGA and ASIC Design with VHDL
• Single-port 128 x 1-bit RAM: RAM128x1S • Dual-port 64 x 1-bit RAM : RAM64x1D
Memories built of 2 MLUTs:
Memories built of 4 MLUTs:
• Single-port 256 x 1-bit RAM: RAM256x1S • Dual-port 128 x 1-bit RAM: RAM128x1D • Quad-port 64 x 1-bit RAM: RAM64x1Q • Simple-dual-port 64 x 3-bit RAM: RAM64x3SDP (one address for read, one address for write)
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Dual-port 64 x 1 RAM
ECE 448 – FPGA and ASIC Design with VHDL
• Dual-port 64 x 1-bit RAM : 64x1D • Single-port 128 x 1-bit RAM: 128x1S
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Total Size of Distributed RAM
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FPGA Block RAM
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Location of Block RAMs RAM blocks
Multipliers
Logic blocks
Graphics based on The Design Warrior’s Guide to FPGAs Devices, Tools, and Flows. ISBN 0750676043
Copyright © 2004 Mentor Graphics Corp. (www.mentor.com)
DSP units RAM blocks
Logic resources
(#Logic resources, #Multipliers/DSP units, #RAM_blocks)
Logic resources (CLB slices)
16
Spartan-6 Block RAM Amounts
17
Block RAM can have various configurations (port aspect ratios)
0
16,383
1
4,095
4
0
8,191
2
0
2047
8+1
0
1023
16+2
0
16k x 1
8k x 2 4k x 4
2k x (8+1)
1024 x (16+2)
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Block RAM Port Aspect Ratios
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Block RAM Interface
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Block RAM Ports
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Block RAM with synchronous read in Read-First Mode
CE
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Features of Block RAMs in Spartan-6 FPGAs