STM32MP257 application processors (STM32 MPUs) are based on a dual Arm® Cortex®-A35 cores running at up to 1.5 GHz and Cortex®-M33 cores running at 400 MHz.
Why do they put a full-desktop-capable A35 processor in the sme product line as the M0 microcontrollers? I presume they're trying to milk value out of the name recognition but they're just diluting the name.
The idea is to move realtime-ish stuff to a popular processor many people have worked with and moving the Linux stuff over to an appropriate platform.
When it came out we used STM32MP257 to demo a quadrature encoder debugger/logger (for internal use, not a product) since the IO supports easy interfacing of encoders. The micro's peripherals (SPI, I2C, GPIO etc.) are easy to program at the register level and you can run a simple mainloop+interrupts thing on the micro, then run Linux for your UI, networking, etc.
The fact that there's not much activity around these kinds of platforms (CPU+micro or CPU+FPGA) suggests it's too hard to combine the two in a way that makes sense for enough people, easier to just use standard components and have them side-by-side on the PCB.
It is nice to have them on the same die, though, for people like myself who like to work on both ends but don't know how to make their own PCBs.
The truth is that those are just niche items. Having a need for both a Linux-grade CPU and a real time MCU-like core is not that common. It tends to show up in projects too advanced for most to attempt.
That's untrue. Almost all the products I worked with in my last company had such architecture - which we leveraged (this was Ag industry). It's very easy to work as they have shared memory to talk to each other.
That's at least a tier more advanced than mainstream.
And if by "very easy to work" you mean "just allocate a shared memory block and put a mailbox in there for the Linux userspace and the RT MCU to talk to each other", you may have inflated expectations of what an average developer using an SBC can easily do. It's "very easy" in the same way rolling your own PCBs or writing your own drivers is very easy. Seasoned developers do it without thinking twice, and then stand dumbstruck when they see entry level developers avoid that like the plague.
Not like we're lacking for the offerings. Plenty of modern SoCs have MCU-like real time cores in them - intended for low power operation, real time control, or both. Even the mainstream RPi 5 boards ship spare PIO and MCU cores - in the RP1 chip. The vendor just couldn't be bothered to document that.
There’s whole sectors of industrial and automotive using these AMP SoMs. And relative to these RPi only recently began providing options that you could design into an embedded product at all. Their FAE and supply presence is way behind.
By "mainstream" I mean "the bulk of development work done", not "the bulk of units shipped".
The boards that people reach for when they roll their first projects, the hardware that ends up in early prototypes and one-off devices, the hardware that gets targeted by open source projects. The chips that return more than a "databrief" 8 pages long and a single page on a vendor site inviting you to visit the snake pit with "contact sales for more information". The boards you can actually buy with a fixed price tag and a delivery to door, and can find writeups on how to use them for specific things.
If you know what "FAE" is, let alone can get into a meeting with one, you're deep in the trenches, and are pretty much expected to wrangle an extremely poorly documented MCU core that happens to be shipped in a SoC as an afterthought into submission.
It’s common for embedded systems to have some powerful cores running Linux and some microcontroller cores running real time code.
The fusion of the two is very valuable if you have applications that require real time work.
> I presume they're trying to milk value out of the name recognition but they're just diluting the name.
No, absolutely not. This is a very valuable structure for embedded work and it’s very common. I don’t know why you’d jump to such a cynical conclusion.
Despite STM32 in the product name, this is a dual core Cortex-A35 SOC intended to run Linux, though he brings it up as bare metal. The STM32MP257F-EV1 dev board that he used costs $425 at Digikey. His thing is interfacing it to FPGA's. So this seems to be a hardware person's product. Most of us can probably use simpler stuff. The Pocketbeagle 2 looks interesting to me.
I think you mean "despite the STM32 in the product name, they're 64 bit compatible cores." Because STM8 was 8 bit (though I've never seen one in any design ever, I'm sure they're just before my time) and STM32 MCUs and MPUs were always 32-bit.
I'm worried they dug too deep a trench with the 32. Like how do much from Espressif is an ESP32 now despite them ranging from slower single core to faster dual core, now even with mmu, some with Wi-Fi some not...
STM32 processors have traditionally been M-series 32-bit ARM cores including M7. I don't know if there have been any exceptions before this. But A-series is application processors with MMU's, DRAM interfaces, etc.
STM8 is still a thing and they were popular cheap embedded boards before ESP32 took over. They were ok as a cheap alternative to Arduino-compatible AVR boards. I have a few of the boards around. They were around $1 each on Aliexpress and have 8K of flash and 1K of ram, which is enough to run interactive Forth, and there's an SDCC compiler target for them.
That's the thing, STM32s are jellybean devices that you can tenth-source from anywhere, including some guy cooking them up in his kitchen in Shenzhen. This thing is an STM32 in name only (SINO? STINO?).
Or they could have just meant STM32 is normally synonymous with "typical slow single-core MCU" compared to multi-ghz Cortex SoCs that we see in higher-end devices that run Linux?
That's marketing. The iMac was a huge hit so Apple started releasing iEverything. Denny's had a hit with its "Grand Slam" breakfast now they have ten different "slams" on their menu,
> And a lot of these parts either don’t have crypto acceleration or security-by-obscurity lock up the docs to the crypto accelerator, which is an absolute dealbreaker for me.
I have to wonder if locking up the docs is some kind of export control or government contract requirement.
I'm so glad we are finally seeing small cores, something to threaten the Cortex A7, which harkens back to 2011!!
But also: Cortex A35 is from 2015! And it's still just a trickle of these small application processor cores. Having a MMU enables so much more. Look at what Baochip and Xous are doing, with small cores but with MMU, for radically better interesting OS / systems architectures.
It just feels so cursed, is so beyond my surprise here well past half way through 202X that so many cores from early 201X are still not just alive but utterly dominant. Something has gone super super super wrong in the House of ARM!
From STMicro:
Why do they put a full-desktop-capable A35 processor in the sme product line as the M0 microcontrollers? I presume they're trying to milk value out of the name recognition but they're just diluting the name.The idea is to move realtime-ish stuff to a popular processor many people have worked with and moving the Linux stuff over to an appropriate platform.
When it came out we used STM32MP257 to demo a quadrature encoder debugger/logger (for internal use, not a product) since the IO supports easy interfacing of encoders. The micro's peripherals (SPI, I2C, GPIO etc.) are easy to program at the register level and you can run a simple mainloop+interrupts thing on the micro, then run Linux for your UI, networking, etc.
The fact that there's not much activity around these kinds of platforms (CPU+micro or CPU+FPGA) suggests it's too hard to combine the two in a way that makes sense for enough people, easier to just use standard components and have them side-by-side on the PCB.
It is nice to have them on the same die, though, for people like myself who like to work on both ends but don't know how to make their own PCBs.
The truth is that those are just niche items. Having a need for both a Linux-grade CPU and a real time MCU-like core is not that common. It tends to show up in projects too advanced for most to attempt.
That's untrue. Almost all the products I worked with in my last company had such architecture - which we leveraged (this was Ag industry). It's very easy to work as they have shared memory to talk to each other.
That's at least a tier more advanced than mainstream.
And if by "very easy to work" you mean "just allocate a shared memory block and put a mailbox in there for the Linux userspace and the RT MCU to talk to each other", you may have inflated expectations of what an average developer using an SBC can easily do. It's "very easy" in the same way rolling your own PCBs or writing your own drivers is very easy. Seasoned developers do it without thinking twice, and then stand dumbstruck when they see entry level developers avoid that like the plague.
Not like we're lacking for the offerings. Plenty of modern SoCs have MCU-like real time cores in them - intended for low power operation, real time control, or both. Even the mainstream RPi 5 boards ship spare PIO and MCU cores - in the RP1 chip. The vendor just couldn't be bothered to document that.
What do you mean by mainstream?
There’s whole sectors of industrial and automotive using these AMP SoMs. And relative to these RPi only recently began providing options that you could design into an embedded product at all. Their FAE and supply presence is way behind.
By "mainstream" I mean "the bulk of development work done", not "the bulk of units shipped".
The boards that people reach for when they roll their first projects, the hardware that ends up in early prototypes and one-off devices, the hardware that gets targeted by open source projects. The chips that return more than a "databrief" 8 pages long and a single page on a vendor site inviting you to visit the snake pit with "contact sales for more information". The boards you can actually buy with a fixed price tag and a delivery to door, and can find writeups on how to use them for specific things.
If you know what "FAE" is, let alone can get into a meeting with one, you're deep in the trenches, and are pretty much expected to wrangle an extremely poorly documented MCU core that happens to be shipped in a SoC as an afterthought into submission.
These parts aren’t designed to be your next Raspberry Pi that mostly gets tossed in a drawer.
Engineers actually use these in real products and embedded systems.
The combination of Linux and microcontrollers isn’t new. It’s a very valuable and common structure.
The comments here trying to dismiss it or call it uncommon are bizarre.
It’s common for embedded systems to have some powerful cores running Linux and some microcontroller cores running real time code.
The fusion of the two is very valuable if you have applications that require real time work.
> I presume they're trying to milk value out of the name recognition but they're just diluting the name.
No, absolutely not. This is a very valuable structure for embedded work and it’s very common. I don’t know why you’d jump to such a cynical conclusion.
Seems normal to me. Microchip also puts their 32-bit and 64-bit chips with their SAM and PIC64 names.
Must be an embedded thing.
Even desktop and smartphone platforms come with MCU grade co-processors these days for low level tasks like power and sleep management.
Despite STM32 in the product name, this is a dual core Cortex-A35 SOC intended to run Linux, though he brings it up as bare metal. The STM32MP257F-EV1 dev board that he used costs $425 at Digikey. His thing is interfacing it to FPGA's. So this seems to be a hardware person's product. Most of us can probably use simpler stuff. The Pocketbeagle 2 looks interesting to me.
> The STM32MP257F-EV1 dev board that he used costs $425 at Digikey
Most would start with the significantly cheaper Discovery Kit version.
With ST, the developer kit is usually only needed if you need every pin and function exposed because you’re developing your own board.
I think you mean "despite the STM32 in the product name, they're 64 bit compatible cores." Because STM8 was 8 bit (though I've never seen one in any design ever, I'm sure they're just before my time) and STM32 MCUs and MPUs were always 32-bit.
I'm worried they dug too deep a trench with the 32. Like how do much from Espressif is an ESP32 now despite them ranging from slower single core to faster dual core, now even with mmu, some with Wi-Fi some not...
What is in a name?
STM32 processors have traditionally been M-series 32-bit ARM cores including M7. I don't know if there have been any exceptions before this. But A-series is application processors with MMU's, DRAM interfaces, etc.
STM8 is still a thing and they were popular cheap embedded boards before ESP32 took over. They were ok as a cheap alternative to Arduino-compatible AVR boards. I have a few of the boards around. They were around $1 each on Aliexpress and have 8K of flash and 1K of ram, which is enough to run interactive Forth, and there's an SDCC compiler target for them.
The MP1 is 7.5 years old now.
That's the thing, STM32s are jellybean devices that you can tenth-source from anywhere, including some guy cooking them up in his kitchen in Shenzhen. This thing is an STM32 in name only (SINO? STINO?).
Eh... that really depends on the part. Some common, old parts like STM32F103 are more or less second-sourcable; others like the STM32H7 series aren't.
Yeah, I was thinking specifically of the STM32F103 and its infinite, ah, informal second sources.
Or they could have just meant STM32 is normally synonymous with "typical slow single-core MCU" compared to multi-ghz Cortex SoCs that we see in higher-end devices that run Linux?
he*
only one person
Singular they is a well attested pronoun in English.
If you don't know English very well I suggest not correcting other people.
"He or she" unless unambiguous, in that case.
Imagine being less character efficient just to be a bigot. Hope you stocked up on RAM for all that extra text
Booooooooooo
That's marketing. The iMac was a huge hit so Apple started releasing iEverything. Denny's had a hit with its "Grand Slam" breakfast now they have ten different "slams" on their menu,
There is STM32MP257F-DK for $103 (without PCIe).
> The Pocketbeagle 2 looks interesting to me.
If only it had 2GB+ RAM. Since it has 4 cores, even more RAM would be better.
And 1Gbit Ethernet is what I'm missing.
> And a lot of these parts either don’t have crypto acceleration or security-by-obscurity lock up the docs to the crypto accelerator, which is an absolute dealbreaker for me.
I have to wonder if locking up the docs is some kind of export control or government contract requirement.
Judging by how ST has reacted in the past it’s likely to discourage people finding vulnerabilities and causing an embarrassment.
I'm so glad we are finally seeing small cores, something to threaten the Cortex A7, which harkens back to 2011!!
But also: Cortex A35 is from 2015! And it's still just a trickle of these small application processor cores. Having a MMU enables so much more. Look at what Baochip and Xous are doing, with small cores but with MMU, for radically better interesting OS / systems architectures.
It just feels so cursed, is so beyond my surprise here well past half way through 202X that so many cores from early 201X are still not just alive but utterly dominant. Something has gone super super super wrong in the House of ARM!
wtf is this? This is not hobbyist domain