3/26/2023 0 Comments Lattice board![]() Xilinx is the dominant player in the field (60ish % market share) so it is natural it will get advised more. In the end, it's about diving in and writing code. NandLand is another site that covers FPGA programming quite well. Other than factory primitives and special features, VHDL is just VHDL. Of course, using the simulation tools with a testbench can do a lot of the same thing. In any event, check out the site I guess I'm not interested in the middle ground, I want a fully featured board like the NEXYS A7 or a minimalist board like the CMOD A7, Since the topic is generating logic chips, or their equivalent, it would seem to me that switches, buttons and LEDs would be a primary requirement. It's also true that everything he presents can be ported to something that works with Vivado (or any other manufacturer and toolchain). It is worth considering the 'stick just to maintain parity with the site. This site is a really great resource with all kinds of really practical examples, especially test benches. As to the Lattice 'stick: VHDLwhiz uses the device extensively and, more to the point, the Lattice toolchain and Modelsim. I don't have the skill or the patience to deal with high pin packages. If I need to embed an FPGA, it will be something like the CMOD A7 mounted to headers or soldered direct. ![]() Furthermore, I won't be building FPGA boards. It's true that the Spartan 6 chips are cheap and I actually like the 5V Spartan 2 devices but there is a steep climb to working with ISE and almost none of it is shared with the next steep climb of working with Vivado. It uses a add-on to the Arduino toolchain, primarily for loading code, and there are a number of alternatives. It is blazing fast with a bunch of memory and easy to work with. ![]() Consider using an ARM CPU like the Teensy 4.1. There is no reason on earth to go back that far! If all you want is gate level logic to mimic 74xx, consider a CPLD. The latest Xilinx tool, Vivado, doesn't support those old chips (it starts with the -7 series) and the older ISE 14.7 toolchain is no longer supported by Xilinx. Whether you have a board or not, you can write some form of HDL that targets the board. Install Vivado and download/install the Digilent Board Files. I find that copy-and-paste works well (sometimes). Or, search the Internet and find a similar project to copy. As I said earlier, you need to spend time clearly defining your requirements. I would hang an SPI type IO Expander or two or three on that PMOD connector and use it for diagnostic widgets. It also has a lot of IO pins but no peripherals. The Digilent Cmod A7 in the 35T variant has a LOT of BlockRAM (225 kB) that should be more than enough to replace a cartridge. Write a bunch of VHDL and see what percentage of the resources are used. Some wild estimate of the fabric requirement. ![]() The Lattice 'stick' is seriously lacking in IO. How much memory does the largest game cartridge have? Does the board have that much? How many IO pins will the project take (and double it.) before considering a board. You would probably load a game dataset from SD card to BlockRAM or SRAM. How much logic, how much BlockRAM to emulate cartridge memory. You need to block out your actual requirements. ![]() What you need is something to get started. It will come to pass that regardless of which board you buy, it own't be the last. ![]()
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