Thunderbolt has always been a functionally proprietary technology, held secret by Intel until “opening” the standard in a way that evidently wasn’t enough for anyone to meaningfully join in. At least, until last year, when we saw announcements about ASMedia developing two chips for Thunderbolt use. Now, we are starting to see glimmers of open source, letting us tinker with PCIe at prices lower than $100 per endpoint.
In particular, this board from [Picomicro] uses the ASM2464PD — a chipset that supports TB3/4/USB4, and gives you a 4x PCIe link. Harnessing the 40 Gbps power to wire up an NVMe SSD, this board shows us it’s very much possible to design a fully functional ASM2464PD board without the blessing of Intel. With minimal footprint that barely extends beyond the 2230 SSD it’s designed for, curved trace layout, and a CNC-milled case, this board sets a high standard for a DIY Thunderbolt implementation.
The main problem is that this project is not open-source – all we get is pretty pictures and a bit of technical info. Thankfully, we’ve also seen [WifiCable] take up the mantle of making this chip actually hobbyist-available – she’s created a symbol, fit a footprint, and made an example board in KiCad retracing [Picomicro]’s steps in a friendly fashion. The board is currently incomplete because it needs someone to buy an ASM2464PD enclosure on Aliexpress and reverse-engineer the missing circuitry, but if open-source Thunderbolt devices are on your wish list, this is as close as you get today – maybe you’ll be able to make an eGPU adapter, even. In the meantime, if you don’t want to develop hardware but want to take advantage of Thunderbolt, you can build 10 Gbps point-to-point networks.
