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  • Author Author: dramoz
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Xilinx Spartan-7 vs Spartan-6

dramoz

Xilinx Sparta-6 was introduced in 2009 and it was a success. Lower cost on development boards, ICs, and free development tools make it a nice add-on for embedded systems that required more computing power (or multiple IO ports - or interfaces) while keeping reasonably cost for such applications. After the Xilinx 7 Series FPGAs were introduced a year later the question was not if but when. Spartan-7 was announced in 2015 - with full production available in 2017.

Here are the main differences between both FPGAs:

Spartan-6 XC6SLX4 XC6SLX150 Spartan-7 XC7S6 XC7S100
Technology 45nm 28nm
Design Suite Xilinx ISE Xilinx Vivado
Logic cells (min/max) 3, 840 / 147,443 6000 / 102,400
Flip-Flops (min/max) 4,800 / 184,304 7500 / 128,000
Total Block RAM (Kbits) (min/max) 216 / 4,824 180 / 4,320
DSP Slices (min/max) 8 / 180 10 / 160
I/O pins (min/max) 102 / 576 100 / 400

A few considerations:

  • Xilinx has archived the ISE Design Suite in favor of Vivado. The latest release was ISE 14.7 (Feb.20, 2020) while Vivado keeps improving and you can expect two releases per year.

    • Xilinx has "two tiers" for it's development tools, Webpack which is free and the paid version(s). As far as could check, Spartan-7 devices are supported on the free Vivado WebPACK tool.

  • The Block RAM in the Spartan-6 is grouped in 18Kb blocks, while the Spartan-7 is in 36Kb blocks.

    • Spartan 7 Block RAMs offer faster FIFO implementations, cascading options, and ECC among other features

  • The DSP blocks are different. While the Spartan-6 DSP48 is built on an 18x18 signed multiplication logic, the Spartan-7 offers a 25x18 multiplier plus other architecture differences that can increase throughput.

  • Spartan-7 devices do not have transceivers like the Spartan-6 LXT FPGAs, but you can go to the Artix-7 FPGAs.

  • XADC: the Spartan-7 comes with a 1 MSPS ADC to internally monitor voltage and temperature, plus external inputs that can be used to monitor board signals.

Spartan-7 FPGAs are based on the 7 Series family, with a smaller technology (implying lower cost / lower power) and furthermore leveraging in a series of architectures updates that increase computing power significantly.

Also, check Adam Taylor’s White Paper Migrating Spartan 6 Design to 7 Series & Beyond for further and deeper information.