Why Spartan-3e is the best ================== Antti Lukats 4.Nov 2005
(I was asked about why I think so in private, but I think my response could have more general interest so I am posting the reply to c.a.f.)
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At first look there differences between S3 and S3e may not be so significant however there are several small things that make Spartan-3e my fist choice (from current low-cost RAM based FPGA offerings).
1) as Spartan-3 was the first Xilinx silicon on new technology its kind of logical that Xilinx has fixed in Spartan-3e some issues related to the use of the new technology. So even if those are minor, there are still chances that S3e is somewhat better simply because Xilinx has had more experience with the technology being used.
2) pricing is promised a little lower, this is not so big deal, but still, its pretty much logical to prefer silicon with best price/performance ratio.
3) S3e configuration options are WAY superior over all other RAM based FPGAs currently in production. S3e is the only FPGA that:
- can load not only from SPI Flash but also from Atmel Dataflash meaning that a it is the only FPGA around that can directly use an MMC (Atmel MMC form factor packaged 2/4/8 MByte Dataflash cards) like Flash card as its main configuration media. So a design with S3e and MMC Card socket can boot from the removabale flash media card. Note that the MMC Card socket inserion switch could overide the 'enable' of the additional on board memory so the SoC loaded from the inserted into socket Dataflash card could copy a new bitstream and OS image onto onboard flash, so next 'boot' without card inserted could come from on board DataFlash. Nice little feature.
- can load from Parallel Flash, just like the oldies (eg Xilinx first FPGA's). This is VERY good feature as it allows cheap Flash ROMs to be used for both config and OS image.
- has 'multi boot' option. In Parallel Flash loading mode S3e can request its own reconfiguration from alternative image.