CPLDs, and the importance of knowing when to quit. (2012) | Hacker News Reader

CPLDs, and the importance of knowing when to quit. (2012)

bytecruft.com

10 pointsparsecs5 comments

http://www.fpga4fun.com/ is a great starting place. FPGA tool chains have a pretty brutal learning curve, but if you have the hardware mindset and can deal with waveforms, they're not that hard. The worst part of the learning curve I found was the subtle issues that are different between simulation and synthesis, along with outright bugs in some of the simulation libraries (Xilinx, I'm looking at you - your simulated FIFOs are buggy!). Sticking to particular coding styles can avoid this (avoid asynchronous resets like the plague), but there is not as much material available on this topic for Verilog and VHDL as with software programming languages. Getting data into and out of a chip is where a lot of these problems crop up. Xilinx's SERDES blocks are absolutely insane to get working the first time one tries. The Microsemi Polarfire was ridiculously easy compared to that. Gigabit ethernet and GMII have weird timing issues that you have to be aware of (ODELAY on the Spartan 6 is needed to satisfy the Marvell PHYs, while other boards with a National Semiconductor PHY don't care about that 1ns).

Maybe it's a bit harder than I admit now that I think about all the battle scars from fooling around with FGPAs over the last 12 years...

Most people don't realize how revolutionary Arduino and Raspberry Pi were in bridging the gap from BASIC PICs to modern day microcontrollers and low cost single board computers. Their efforts forced manufacturers across the world to design for both layman and professionals, without which we would all still be using IDEs costing several hundred dollars. Even FPGAs now are slowly embracing open source and user friendly UIs.

Raspi - definitely

Arduino - hmm, I don't think so. Arduino seems to have made it a lot easier, but Arduino used a pretty open platform from the start, so it didn't remove any hard barriers to entry (compiler/tooling). Arduino (on AVRs) always used AVR-GCC and AVR libc, which came before Arduino/Wiring. AVRs also had free/open tools for programming before Arduino (parallel port programmer and other DIY tools).

The whole is greater than the sum of its parts. Even now many programming language ranking boards are still fooled into believing that "Arduino" is a separate language and not just C/C++ with header and Make files hidden behind a pretty IDE.

> Programmable logic chips seem to lag behind MCU's in the hobbyist-friendly area

Definitely true.

But the slow march of progress continues, and the state of affairs today is actually pretty okay!

There's a variety of hobbyist-friendly ~$50-$100 boards that are programmable via a plain old USB cable [1][2][3].

There's also an open-source toolchain that is small, fast, and works well [4].

[1] https://tinyfpga.com/

[2] https://1bitsquared.com/products/icebreaker

[3] https://groupgets.com/manufacturers/good-stuff-department/pr...

[4] https://symbiflow.github.io/

Reply on news.ycombinator.com