Comment by adrian_b

Comment by adrian_b 14 hours ago

There are no similarities between Cortex-M7 and Cortex-A7 from the POV of obsolescence.

Cortex-M7 belongs to the biggest-size class of ARM-based microcontrollers. There is one newer replacement for it, Cortex-M85, but for now Cortex-M7 is not completely obsolete, because it is available in various configurations from much more vendors and at lower prices than Cortex-M85.

Cortex-M7 and its successor Cortex-M85 have similar die sizes and instructions-per-clock performance with the Cortex-R8x and Cortex-A5xx cores (Cortex-M5x, Cortex-R5x and Cortex-A3x are smaller and slower cores), but while the Cortex-M8x and Cortex-R8x cores have short instruction pipelines, suitable for maximum clock frequencies around 1 GHz, the Cortex-A5xx cores have longer instruction pipelines, suitable for maximum clock frequencies around 2 GHz (allowing greater throughput, but also greater worst-case latency).

Unlike Cortex-M7, Cortex-A7 is really completely obsolete. It has been succeeded by Cortex-A53, then by Cortex-A55, then by Cortex-A510, then by Cortex-A520.

For now, Cortex-A55 is the most frequently used among this class of cores and both Cortex-A7 and Cortex-A53 are truly completely obsolete.

Even Cortex-A55 should have been obsolete by now, but the inertia in embedded computers is great, so it will remain for some time the choice for cheap embedded computers where the price of the complete computer must be well under $50 (above that price Cortex-A7x or Intel Atom cores become preferable).

kvemkon 10 hours ago

In embedded old Cortex-A53 (and A72) are the most "new" cores used compared to A9 (and A15). E.g. TI AMxxxx [1] and Xilinx UltraScale+ vs Zynq.

[1] https://www.ti.com/microcontrollers-mcus-processors/arm-base...

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adrian_b 8 hours ago

For cores included in FPGAs, sadly there are none better than Cortex-A53 and Cortex-A72, because there have been no significant upgrades to the families of bigger FPGAs for many years. However in that case you buy the chip mainly for the FPGA and you have to be content with whatever CPU core happens to be included.
On the other hand, for the CPUs intended for cheap embedded computers there are a very large number of companies that offer products with Cortex-A55, or with Cortex-A76 or Cortex-A78, so there is no reason to accept anything older than that.
Texas Instruments is not really representative for embedded microcontrollers or computers, because everything that it offers is based on exceedingly obsolete cores.
Even if we ignore the Chinese companies, which usually have more up-to-date products, there are other companies, like Renesas and NXP, or for smaller microcontrollers Infineon and ST, all of which offer much less ancient chips than TI.
Unfortunately, the US-based companies that are active in the embedded ARM-based computer segment have clearly the most obsolete lines of products, with the exception of NVIDIA and Qualcomm, which however target only the higher end of the automotive and embedded markets, by having expensive products. If you want something made or at least designed in USA, embedded computers with Intel Atom CPUs are likely to be a better choice than something with an archaic ARM core.
For the Intel Atom cores, Gracemont has similar performance to Cortex-A78, Tremont to Cortex-A76 and Goldmont Plus to Cortex-A75; moreover, unlike the CPUs based on Cortex-A78, which are either scarce or expensive (like Qualcomm QCM6490 or NVIDIA Orin), the CPUs based on Gracemont, i.e. Amston Lake (Atom x7000 series) or Twin Lake (N?50 series), are both cheap and ubiquitous.
The latest Cortex-A7xx cores that implement the Armv9-A ISA are better than any Intel Atom core, but for now they are available only in smartphones from 2022 or more recent or in some servers, not in embedded computers (with the exception of a product with Cortex-A720 offered by some obscure Chinese company).

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crest 9 hours ago

Does anyone but Renesas even offer a Cortex M85 based MCU? Afaik the all the other high performance ARM based microcontrollers still use a Cortex M7 except for a few M55 based chips.

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adrian_b 7 hours ago

In general Renesas offers more modern microcontrollers than all the other vendors of MCUs, which have decreased a lot the rate of new product launches during recent years, but unfortunately they are also among the most expensive.
I have also not seen Cortex-M85 except from Renesas. Cortex-M55 is seldom an alternative to Cortex-M7, because Cortex-M55 is smaller and slower than Cortex-M7 (but faster than the old Cortex-M4 or than the newer Cortex-M33).
Cortex-M55 implements the Helium vector instruction set, so for an application that can use Helium it may match or exceed the speed of a Cortex-M7, in which case it could replace it. Cortex-M55 may also be used to upgrade an old product with Cortex-M7, if the M7 was used only because Cortex-M4 would have been too slow, but the full speed of Cortex-M7 was not really needed.

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duskwuff 4 hours ago

Rumor has it that ST has one on the way (STM32V8).

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