New Part Day: The STM32 That Runs Linux

There are a lot of ARM microcontrollers out there, and the parts from ST are featured prominently is the high-power builds we’re seeing. The STM32F4 and ~F7 are powerhouses with great support, and the STM32F0 and the other younger children of the family make for very good, low-power microcontrollers. Now, the STM32 family is getting a big brother. It runs Linux. It’s two ARM Cortex-A7 cores and one M4 core on the same chip. The STM32MP1 is the chip you want if you still can’t figure out how to waste computing cycles by blinking LEDs.

Block diagram of the STM32MP157 Image: ST

First, that Linux support. The STM32MP157C was mainlined into Linux last summer, and there is support for Android. So yes, this chip can run Linux. There is an optional 3D GPU in this family, a MIPI-DSI controller, support for HDMI-CEC, USB 2.0, and 10/100M or Gigabit Ethernet. This brings us the inevitable question of whether you can build a Raspberry Pi clone with these parts. Maybe, champ, but if you’re asking that question it’s probably not you that’s going to build one. It looks as if this chip is designed for phones, set-top boxes, and smart TVs. That doesn’t preclude a single board computer, but the biggest problem there is maintaining software support anyway.

The chip family in question all come with dual ARM Cortex-A7 processors running at a nominal 650MHz. There’s also a Cortex-M4 running at 209MHz, and the ST literature suggests that engineers are already running Linux on the A7 and an RTOS on the M4. This chip will need external memory, but DDR3 / DDR3L / LPDDR2 / LPDDR3 are supported.

This chip is only announced right now, you can’t get it on Mouser or Digikey yet, and there’s no information on pricing. However, there are two development boards available, the Evaluation board, which features 1 GB of DDR3L, 128 MB of Flash, and an 8 GB eMMC. There’s a 5.5″ display, and enough connectors to make your heart flutter. The Discovery board is a bit more cut down, and comes with a 4″ 480×800 LCD, WiFi, Bluetooth LE, and of course it comes with GPIO expansion connectors for an Arduino and Raspberry Pi. The Discovery Board is not available at this time, but it will sell for $99 USD.

44 thoughts on “New Part Day: The STM32 That Runs Linux

    1. How did they write this article without the price.

      HaD editors maybe we can get a bottom of article proforma like on review sites?

      Price, where to buy, availability, licensing

  1. All of these SBC’s are using TV box processors. This looks like a half decent IoT platform. There are, of course, the Atmel (I mean “Microchip”) linux-capable SoC’s as well.

  2. Pros:
    – mainline kernel and U-Boot
    – preempt-rt support (just apply the patches on the mainline)
    – decent meta layer for Yocto
    – eval board is cheap (the BOM is pretty buffed up)
    – ST has solid support
    – lot of nice development tools

    Cons:
    – slow processor which is ok for basic iot stuff but not for more fancy things
    – until a cheaper board comes out, it’s price is high for general purpose board. Better buy an RPI

    1. Yeah, I have one here. I must say I’m a bit underwhelmed by the package. The linux support is more like, “you can write cool firmwares using 2 Cortex-A7 cores and oodles of RAM using standard Linux programs” rather than “This is a fully functional Linux system and for your hard real-time requirements you can simply load up the MCU with a special firmware”.

      I was hoping this would be more like the usual SoC kind of system but with the addition of a nice MCU for the low-level stuff. Like a Lattepanda but based on ARM and instead of that shitty “Arduino” ATMega a proper MCU.

      It is nothing like that though, the standard OpenSTLinux is barely useable as standalone system let alone providing any way to develop for the MCU (even the on-board ST-Link V2-1 to program the MCU is connected to a separate Micro-USB port).

  3. Earlier this week I got a promotional email from Octavo systems who make the system-in-a-package (SIP) used on some of the Beaglebone boards that they will be making a SIP with this chip. IMHO the important thing will be a good software ecosystem for this. So many ARM SBCs come & go because their software support is lacking

  4. The part I find compelling is the M4 co-processor for real-time offload. You should be able to use it sort of like the PRUs in the TI AM335x parts (in the Beaglebone and co.), but in return for being very slightly less tightly-coupled to the host, it runs the same bog-standard ARM code as the already-common stm32f4 micros instead of custom PRU assembly.

    Should be really nice for making things like machine controllers with a small real-time component and a built-in human interface / network support / higher-level compute task.

  5. I want something in between with megabytes of memory at the most and a vram-like framebuffer you can write to. That would be a perfect tool for building a great limited-spec educational console.

  6. I think the biggest advantage over BCM28xx, Allwinner Hx and other set-top-box CPU would be decent power management and generally low power consumption. Current developement board is a little bit expensive in comparison to RasPi but it’s better suited to battery use and knowing ST policy – cheaper nucleo-style boards can appear. I would also love to see something like Allwinner V3s – with integrated RAM and friendly TQFP package but with great documentation.

  7. Per the svd file that st released (not everyone does this btw) I count 121 peripheral blocks. St documents their chips well, easy to use. I do see nxp has a quad core a53 with an cm7. 1.5ghz and 600mhz respectively to sts dual core a7 and cm4 at 650mhz & 209mhz.

    1. These are well documented SOCs that are optimized for low power and come with proper documentation, software and support i.e. not disposable junk like some of these Amlogic and AllWinner SOCs. They’re also not intended to be used in TV boxes that run Android and Kodi. It’s a different market completely.

      1. Yeah, pretty sure the quality of support and documentation between Allwinner and STM are also in the same ballpark… It seems the difference between tool and toy is still not widely known.

        1. Perhaps, But I still prefer to use more expensive, better designed SOCs with better documentation and support than what AllWinner offers and I’m happy to pay a premium for it. I’m sure others would be willing to do so as well, otherwise STMicro wouldn’t be releasing a new part in this sector.

          AllWinners are OK for disposable Kodi boxes; not reliable embedded systems.

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