I'm planning to start some projects using the Arduino Due. While gathering some informations about the MCU I stumbled upon the "Status: Not Recommended for new designs"-notice along with the fact that this MCU is categorized as "Legacy Product"
I think this might be due to the Atmel->Microchip transition and leaves me rather uncomfortable when planning things like a home automation, where the availability after a couple of years is a key aspect.
Are there any plans for a successor? Microchip seems to provide ARM-MCUs in M0+, M4 and M7 flavours. The Cortex M4 would be my favorite choice since it gets some love as target for the Rust programming language.
We have no special insight into the inner workings of Microchip, or their commercial plans. However, they claim to provide their products as long as it will be necessary:
A History of Product Longevity At Microchip we have a 25-year practice of not putting our clients through the pain and cost of redesigning for end-of-life. We call it client-driven obsolescence, and the idea is very simple: we will supply a product as long as there is a customer somewhere who wants it. Five years? Ten Years? Twenty? You decide.
I think this might be due to the Atmel->Microchip transition
nah. SAM3X was on its way out even before that. MOST manufacturers seem to be abandoning the CM3 chips in favor of either CM0/CM0+ or CM4. I'm not sure exactly why. TI "NRND"ed the whole rather extensive line of Stellaris CM3 chips in favor of a much smaller range of CM4 products, for example.
Are there any plans for a successor?
SAMD51 (a 120MHz CM4F) is looking promising. Adafruit is shipping their "Metro M4" with the 64pin chip, and had made noises (but no commitments that I know of) about doing a Mega/Due size board (the SAMD51 range goes from 48pin to 128pin chips...) Adafruit Metro M4 feat. Microchip ATSAMD51 : ID 3382 : $27.50 : Adafruit Industries, Unique & fun DIY electronics and kits
In general, vendors seem to be concentrating on lower pin-count boards. I find it a little depressing that the Metro M4 uses a 64pin chip to end up with an Uno-style pinout, but they have extras (I2C and SPI pins are separate from other IO, there's a QSPI flash chip, a NeoPixel, native USB (w LEDs), and a SWD connector...
And PJRC's Teensy 3.6 is a CM4F with more-than-uno pins, but not Due form factor. Teensy® 3.6
JLLL:
You may try STM32 chips, they got much more variants than arduino.
And an awful support library with very few working examples available for how to do stuff with the peripherals. Forget thousands of tried and true libraries and code snippets. I wish I didn't spend so much time trying to get things work with STM32 before I discovered Arduino. Yes, STM32 chips are great hardware, but I've learned the hard way hardware alone isn't enough, and I would only recommend STm32 to my enemies.
I assume there's no successor or replacement for the Due
Adafruit has the "Grand Central M4 Express", which seems like a pretty worthy replacement (side from being semi-perpetually out-of-stock. I have the smaller "Metro M4 Express")
For whatever reason. Cortex-M3 chips seem to be going "out of favor", with most newer chips being Cortex-M4 instead (sometimes with floating point!)
The TI "Tiva" Series is another possibility that has Arduino ("Energia" support) as well as other choices.
The "MEGA" form factor also seems to be relatively unpopular. Too short to fit things on, too wide (just barely) to fall into the "Cheap PCB" category.
That page now says "Status: In Production", and I don't see any mention of "legacy" or "NRND"...
This may be due to the Microchip acquisition of Atmel. In general, Microchip keeps selling products FOREVER (ok, it looks like the PIC16C84 is EOL. But the drop-in pin and code compatible PIC16F84A is still sold...) Atmel wasn't nearly as "continuity conscious"...