Engineer bends STM32MP2 application processor into a bare-metal microcontroller
Playing with the STM32MP2
The STM32H7's FMC eats 30+ pins scattered across the BGA, making FPGA pairing painful on cheap boards. So the author tried the STM32MP2 — a dual Cortex-A35 SoC built for Linux — and forced it to behave like a plain MCU: upstream aarch64 g++ only, no vendor SDKs, no DDR, no TrustZone or u-boot, everything in on-die SRAM, an event loop in EL3, and PCIe to an FPGA. Along the way he stumbled on a silicon bug with security implications.
I just wanted a big microcontroller that could run a simple RTOS or even a while(1) { doStuff(); } event loop.
- throwaway81523
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.
- dlcarrier
From STMicro:
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.
- ranger_danger
> 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.
- jauntywundrkind
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!
- brcmthrowaway
wtf is this? This is not hobbyist domain