Are 4.0s also going the way of 3.2 ?
IMXRT chips for Teensy 4.0, 4.1 have been much better than the Kinetis parts on Teensy 3.2, 3.5, 3.6. NXP hasn't delivered the older Kinetis parts about September 2021. We had a pretty good number stockpiled, so Teensy 3.5 & 3.6 ran out by December 2021, and Teensy 3.2 ran out by early February 2022.
So far for 2022, IMXRT chips have arrived at approximately the rate scheduled. But because Teensy 3.2, 3.5, 3.6 are gone, many people switched to Teensy 4.0, 4.1 which means the amount we ordered (about a year ago) isn't enough. Teensy 4.0 and 4.1 have been running out, then coming back briefly, and running out again. We're trying to get more IMXRT chips, but all signs are looking like we'll continue with this trend for the next 2-3 months where we can't quite make enough to fully meet the new demand because we're receiving the number of chips anticipated over a year ago when Teensy 3.2, 3.5, 3.6 were still available.
Right now, we have a batch of Teensy 4.0 completing production. It's a process that happens over 3-4 weeks, not all at once. The first part of this latest batch arrived last week. Almost all of them shipped to distributors. Those Amazon sellers who recently ran out had stock from the prior batch which finished about a month ago. Over the next few weeks, the distributors will probably place orders which consume this entire batch, which will cause PJRC to be out of stock again... even as we're still getting more out of production each week and shipping them to fulfill those distributor orders. So even though the website gives the appearance none are left, the reality is distributor backorders have claimed them all, and they're gradually completing production and getting shipped to those companies. Then we wait for more IMXRT chips, and the cycle repeats where we are getting more around the time stock distributors bought from the last batch is running out. Ideally we'd get the chips earlier so there wouldn't be any gaps, but even though the IMXRT chips are arriving steadily, it's the rate we forecast over a year ago before we knew how bad the chip shortage would become.
Indeed the shortage is terrible for the Kinetis chips on Teensy 3.2, 3.5, 3.6. Earlier this year we were told the chips would have "gradual improvement in Q2" and most would ship in Q3 & Q4. But now NXP is telling us the Kinetis chips won't be available until well into 2023, with a small quantity of the Teensy 3.2 chip in Feb-Mar time frame and the rest in the summer (or 2023).
What the future holds for IMXRT, beyond the next few months, I just don't know. We have a lot of chips on order from NXP. Whether they'll continue delivering as they have so far this year, or those too will dry up without warning as the Kinetis parts did, I honestly don't know. Lately it's become difficult to get any info or answers about when chips will really arrive.
Best I can tell you is the situation you're seeing today, where Teensy 4.0 is sometimes in stock, sometimes unavailable, is due to chips arriving according to a sales forecast Robin & I made over a year ago, before we know the supply of Kinetis parts would dry up. Normally we try to keep a small "buffer" of extra chips, but lately we don't have any extra. They do into production as soon we get them. The IMXRT chips are arriving from NXP (or have been lately - future is impossible to predict), just not at a fast enough rate to fully meed the new level of demand. So for at least the next few months, you're likely to keep seeing this in stock, then out of stock, then back again briefly pattern keep repeating. It's the best we can do right now.