Short articles about my experience with the Google/Efabless/Skywater130 ASIC process, interviews and any other related topics I think are interesting.
Interview with Arya Reais-Parsi - FPGA fabric
In this interview I talk with Arya Reais-Parsi about their shuttle submission. They are working with a group of students to create Open Source FPGA fabric that can be put on an ASIC and configured with yosys/nextpnr. The repository is here.
Interview With Sylvain 'tnt' Munaut: USB peripherals
In this interview I talk with Sylvain ’tnt’ Munaut about his Google/Skywater ASIC application. The design is especially interesting to me because of the way it merges the SRAM blocks with the logic. This has been a major challenge in my own design. Here’s the link to the repository
Interview With Vladimir Milovanović - spectrometer with Chisel
In this interview I talk with Vladimir Milovanović about putting a spectrometer on the Google/Skywater/Efabless ASIC shuttle. He created the design using Chisel. The repository is here.
I’ve always thought the artwork people put in the top layer of their chips was cool. Do a google image search for chip artwork to see some more fun examples. While waiting for some toolchain bugs to get ironed out I’ve made a tool to help me make logos. It can take SVG or PNG input and makes a GDS2 file output. These files can then be merged together to create the final layout for the ASIC.
How Much Can We Fit on an ASIC?
The Google / Skywater shuttle reserves about 10 square mm (10 million square microns) of space for your design. This comparison that Mohamed from efabless put together shows the various areas (and time to generate the GDS2 files) of some popular designs. We could fit in about 10 picorv32 RISCV cores! My designs I currently have 3 designs ready to add to the multi project harness: Name Square microns How many would fit?
This is one of the first projects I hardened using OpenLane. News update: my clock works! Still can't quite believe I have a clock on my desk that is powered by a chip I designed! pic.twitter.com/O5c2omQYYp — Matthew Venn (@matthewvenn) March 31, 2022 It shows the time on an LCD panel. It will be part of my first tapeout. After running the OpenLane ASIC flow, it results in a design that uses 180x180 microns (32000 square microns).
Multi Project Harness
The Google/Skywater Shuttle has about 10 square mm of space for your project. This sounds tiny but is actually HUGE for many beginner projects. Read this post to find out what you could fit in the user space. For the Zero to ASIC course, I want to aggregate all your designs together into that area, so we need to do some extra bits: Multiplex all the inputs and outputs of your project to the GPIO pins of the Caravel harness.
Hackaday #remoticon talk
I recently presented a demo/presentation for Hackaday’s #remoticon. slides from the talk presentation tools
A standard cell is a building block that contains some basic digital or analogue functionality. These blocks are then tiled together to make the final design. Since finding out about the Skywater PDK, I wanted to try drawing my own ‘standard cell’ using the Skywater transistor models. An inverter is one of the simplest and even that was quite difficult! As you can see below it contains an N and P type MOSFET.