It’s A Doughnut, In Hardware

Making a physical doughnut is easy enough, given a good dough recipe and a nice hot deep fat fryer. But have you ever considered making a one in physical electronic hardware, on an ASIC? [A1k0n] has, at least in terms of making a virtual doughnut. It’s a hardware implementation of a ray tracer which renders a rotating doughnut to a VGA screen, and it comes courtesy of around 7000 logic cells on the latest iteration of Tiny Tapeout.

We will not pretend to be mathematical or ray tracing experts here at Hackaday so we won’t presume to explain in detail the circuitry, suffice to say that the clever hack here lies in a method using only shift and add operations rather than the complex trigonometry we might expect. It uses a slightly esoteric VGA mode to work with the device clock, so while CRT monitors have no problems it can have artifacts on an LCD. The full explanation goes into great detail, for the math heads among you.

We’ve reported on quite a few Tiny Tapeout projects over the years, as the many-ASICs-on-a-chip extends its capabilities.

A Demo Party On A Chip

The demoscene has provided our community with its artistic outlet since the first computers which could handle graphics, and has stayed at the forefront of technology all the way. For all that though, there’s a frontier it hasn’t yet entirely conquered, which exists in the realm of silicon. To address this cones the ever awesome Tiny Tapeout, who are bringing their ASIC-for-the-masses scheme to the world of demos with an ASIC demo competition.

With a closing date of 6th of September, all accepted entrants get a free Tiny Tapeout tile for their entry. Entries are limited to two tiles or less. with VGA and audio outputs via a specified PMOD pinout. There are a variety of categories including the expected best sound and best graphics, but among them we’re most interested by the mixed signal one that includes analogue circuitry.

Tiny Tapeout has been a particularly exciting project over the last couple of years, truly breaking new ground for the hardware hacker world. Since they’ve just recently been able to start doing some analog design on the chips, we’re excited to see what people come up with for this competition, and we hope it will provide significant advancement to the art. In the best tradition of the demo scene, they’ve even made an intro for the competition, which you can see below the break.

Want to know what all the fuss is about? Start here!

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Analog ASIC Design Built Using Digital Standard Cells

Tiny Tapeout is a way for students, hobbyists, and home gamers to get their own ASICs designs fabbed into real custom chips. Tiny Tapeout 3 was the third running, with designs mandated to be made up of simple digital standard cells. Only, a guy by the name of [Harald Pretl] found a way to make an analog circuit using these digital cells anyway.

In a video on YouTube, [Harald] gave an interview on how he was able to create a temperature sensor within the constraints of the Tiny Tapeout 3 requirements. The sensor has a range of -30 C to 120 C, albeit in a relatively crude resolution of 5 degrees C. The sensor works by timing the discharge of a pre-charged parasitic capacitor, with the discharge current being the subthreshold current of a MOSFET, which is highly dependent on temperature.  [Harald] goes deep into the details on how the design achieves its full functionality using the pre-defined digital cells available in the Tiny Tapeout 3 production run.

You can checkout a deeper breakdown of [Harald]’s design on the submission page. Meanwhile, Tiny Tapeout creator [Matt Venn] gave a great talk on the technology at Hackaday Supercon last year.

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