Electronic Design

Ready To Rock FPGA Development

It’s been ages since DLP Design dropped off their FPGA and PIC development tools (see FTDI And DLP Design Deliver FPGA Dev Tool), but I've finally been able to try them out. These two tiny units were lost in the pile of boxes that's been accumulating in the lab — but they certainly pack a noticeable punch. The DLP-FPGA and the DLP-FLASH2 cost $189 and $29, respectively. The former holds an Xilinx Spartan 3E FPGA, while the latter accepts target boards with Microchip PIC16 and PIC18 devices. It can be used as a general PIC programmer/development tool. The DLP-FPGA targets FPGA developers and those looking to gain a background with FPGA design. It can operate as a standalone device. OEM versions are available for $119 without the development tools. The DLP-FLASH2 is designed for PIC developers. A number of target boards are available and it is easy to build your own. The target boards are typically used in standalone applications after they are programmed using the DLP-FLASH2. The two products address radically different functions but share a common USB interface, thanks to Future Technology Devices International (FTDI). FTDI delivers a range of USB-based controllers, including the Vinculum Embedded USB Host Controller (see Design Transfers Between Two USB Storage Devices). Ready To Rock FPGA Development The DLP-FPGA (Fig. 1) houses the Spartan 3E FPGA on a carrier board. As noted, the FTDI USB chip provides an interface between a development PC and the FPGA. It can program the boot flash and provide basic debugging support. The package includes the ISE WebPACK software from Xilinx. This is the stock package, so if you've used ISE before, you'll feel right at home. There are minimal details about the DLP-FPGA board in the docs, although he full schematics of the board are included. What is lacking is a more step-by-step installation and instruction procedure for this specific device. Still, all the information and procedures are there. You just need to be a little patient and read everything first. Luckily, you deal with ISE exclusively once the installation is done. The training manual assumes experience with both FPGAs and ISE or a similar tool. An accompanying book would be a good idea for introducing novices, but that's usually taken care of by college curriculum. For those on their own, check out some books like FPGA Prototyping By VHDL Examples or Design Recipes For FPGAs to augment the accompanying training manual. I was up-and-running with the kit in one afternoon, although I've used ISE in the past (see FPGA 2: Xilinx Embeds Processors). ISE can handle almost anything you throw at it and it's the same tool used for the other Xilinx parts, so the DLP-FPGA is a good stepping stone. Its FPGA is large enough for soft cores like Xilinx’s MicroBlaze (see Multicore Trouble? Try An FPGA). The 50-pin DIP-style (0.9-in centers) connector provides access to the FPGA’s IO pins (40 total) and you can supply or deliver 5V of power off some of the pins as well. The FPGA has access to 128Kbytes of SRAM and the SPI flash is accessible to the FTDI chip. The SPI flash is booted by the FGPA in standalone mode. Dealing with FPGAs continues to get easier, but this kit makes it almost trivial. Implementing basic logic on this platform was a simple first step. Moving up to a MicroBlaze takes a bit more work, though from a procedural standpoint. I'm convinced that it's an inexpensive alternative for FPGA development, as well as an excellent alternative for producing a product in small quantities since you don’t have to deal with FPGA layout and power-supply headaches. PIC Your Alternatives The DLP-FLASH2 (Fig. 2) is a nice alternative to the $49 Microchip PICKit 2 (see Microchip Delivers PIC Development Tool For $49). The main difference is the size of the target board and debugger. The DLP-FLASH2 is smaller on both counts, but this has advantages and disadvantages. On the plus side, it's cheaper and the target board is more compact. It's also easier to plug into another device since it can accept a standard header. But soldering is required, and there's a loss of prototyping area. Both approaches are USB-powered and both work with Microchip’s ICD development tools. In fact, for ICD developers, switching to the DLP-FLASH2 is a trivial exercise. I happened to have the latest ICD 2 software and the transition was essentially transparent. Microchip delivers great development tools and they are free so PIC developers will have a field day with the DLP-FLASH2. The DLP-FLASH2 comes with a 16F88-based target board. There are also boards available with a 16F917 (DLP-uCF917), 18F2321 (DLP-uCF2321) and 18F4420 (DLP-uCF4420). These all have the 6-pin header for the debugger. You can also build your own. Designing in this type of header is a trivial PCB design exercise. Getting up-and-running from scratch should just require a download from the Microchip website to get the latest software. The rest is easy. Just select the target’s 16F88 chip type and start banging out assembler or C/C++. The latter is available in a free student edition, or a production version can be purchased separately. The optimizations available in the latter are significant. Related Links DLP Design Future Technology Devices International Ltd. Microchip Xilinx

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