If you replace the Teensy 4.x it would have to be something very close to the same pinout, foot print, cost and features otherwise it would just be a new product. Ideally you would find a way to source the Teensy directly bypassing Sparkfun.

sparkfun is the single source supplier (and now maker of the product).

Spinning an IMXRT1062/IMXRT1064 design sans the terrible Teensy bootloader should take a day or two at most.

These chips have perfectly-fine ROM USB bootloaders and SWD, don't ruin them by adding extra garbage.

The layout of the Teensy 4.x was challenging as I recall with the speeds involved. But maybe you are a demigod of compact high clock designs.

Nothing on that board is remotely high speed or challenging.

USB HS on a board that small is a non issue: it's one measly differential pair with easy impedance requirements.

Go ahead and make one then, we'll be thankful.

Yes, obviously, but they don't make the chips, so can't you just source the exact same chip, make thing pin compatible and call it a day? Then you'd have a drop in replacement, any changes you make will cause disruption for people downstream.

https://www.nxp.com/part/MIMXRT1062DVL6A

Mostly I'm just leery of software defined peripherals being at the mercy of whatever community springs up around them, nothing specific. In terms of a Metro then yeah, something to slot in where the Due was absolutely with high speed USB, 10/100 ethernet, CAN FD, and all that jazz that wouldn't work on a $10 board. A SAMV70 successor to the Due?

NXP just seems antithetical to an open platform. Then again Arduino went with Renesas, and they're… not great.

Otherwise it's the openness that would pique my interest. SWD headers, yes 100%. But also the documentation. No half-assed SVDs, buggy closed source flash algorithms (Microchip), wholly undocumented peripherals (looking at you Renesas), stuff like that.

All chip manufacturers are alike in this respect, unfortunately. That whole industry believes that they thrive on secrecy and that simply properly speccing their hardware would already be a massive competitive risk.

Nah, it's a spectrum. Companies like NXP and Infineon are at one end. NXP wants a ton of personal information to access even the most basic docs on some of its chips, sometimes even an NDA. Infineon won't even acknowledge you for the most part.

Companies like STM, RP, and TI are at the other end. STM got super popular because they're cheap and the documentation is incredibly easy to get at. I think RP is following suit.

Renesas puts out some documentation, but it's really rough. Anything that has even a whiff of crypto is completely undocumented. They're also squatting on a few Rust crates where Espressif actually hired a Rust developer to work on their Rust HAL. The most comical thing is that while they version their reference manual they don't seem to update it and instead issue a ton of broad errata that apply to multiple manuals.

Before the acquisition Atmel's documentation was well written and organized.

That's fair. Even so, the majority of the companies whose chips I would consider for specialized electronics seem to be so far down on the paranoid spectrum that it hinders their business.

Sure, some do, but some are coming around and some were never there. Which is why it's important for a company like Adafruit to pick a manufacturer that is towards the open end of the spectrum. Unfortunately NXP isn't that manufacturer even if their silicon is more powerful.

Agreed. I will say that Renesas does have one thing going for them, being Japanese it has the lowest supply chain/geopolitical risk right now of anybody other than TI. And the Microchip/Atmel low end stuff is so overpriced/outdated, that you're be better off stockpiling reels of the 8 cent Puya chips or going with the the TI MSPM0.