SigmaStar SSD201/SSD202 powered 4G LTE industrial gateway made to run mainline Linux

SigmaStar SSD201 is a dual-core Cortex-A7 processor with 64MB RAM onchip that is designed for smart HD displays. We’ve previously seen it in Industio 7-inch smart display running Linux, but if you want to modify anything you’d need sign an NDA before getting the SDK.

Luckily there’s an open-source community named linux-chenxing that aims to bring mainline support to those low-cost SigmaStar processor to mainline, the same way linux-sunxi is working on Allwinner processors. Daniel Palmer noticed MYZR recently launched GW300 4G LTE industrial gateway with specifications that looked familiar.

GW300 specifications from manufacturer’s website:

  • Processor – Arm Cortex-A7 dual-core processor @ 1.2GHz
  • Memory – 64MB RAM
  • Storage – 128MByte Flash
  • Connectivity – Ethernet and 4G LTE with high-gain antenna
  • Serial – RS485/ RS232 via 5-pin terminal block
  • Misc – RTC
  • Power Supply – 12V to 24V DC input
  • Dimensions – 127.7 x 87.5 x 30 mm
  • Temperature Range – -20°C to +75°C

The gateway runs Linux and supports ModBus and MQTT for all sort of industrial IoT applications. But just to make sure Daniel bought a sample and took it apart…

It turns about this particular model is based on a SigmaStar SSD202D dual-core Cortex-A7 processor that is supposed to come with 128MB RAM, and also includes a LongSung M5710 4G LTE Cat 1 modem (See AT commands set PDF), ISL1208 RTC chip, SIPEX 3232EE RS232 transceiver, and SP3485 RS485 transceiver.

What even more interesting that he managed to port mainline U-boot and mainline Linux to the gateway:


That’s U-boot 2021-01 RC4 with Linux 5.11 RC4 boot from the SPI NAND flash. You can check out the full boot log if you are interested.  Many things are already working in Linux 5.11, and Daniel submitted a patch to add support the M5710 modem in Linux 5.12. Eventually, OpenWrt may be ported to the gateway if there’s enough interest from the community. You’ll find additional information on Github.

There may seen be more progress made on open-source software around SigmaStar processors, as I’ve been told the company released the SDK publicly on their website where registration is required together with a China Mobile number, and Widora is current developing a SSD202D module and posted (parts of) the SDK on Github.

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21 Replies to “SigmaStar SSD201/SSD202 powered 4G LTE industrial gateway made to run mainline Linux”

    1. As someone who buys too much stuff from AliExpress

      1) How do you get started developing on a board with no info / limited / outdated SDK?

      2) How can I too, buy from Taobao instead?

      1. Taobao has something called the consolidating warehouse. You don’t need to use a third party.

        First identify EVERYTHING you want to buy from taobao. I recommend adding lots of cheap stuff like jumper wires, connectors, etc. Then buy all of the things you want and select delivery to the international warehouse. That step of delivery is quite inexpensive, a few yuan.

        Next login and start checking your consolidated warehouse account. Watch for all of your orders to arrive at the warehouse. When they all arrive select the option to mail then to your destination country. Taobao will package them up and send them in a single shipment billing you for FexEx, DHL or whatever you pick. This is not too bad maybe $20-30. But all of your orders are in a single DHL box which is what makes this so attractive. You pay the $30 once, not once for every order.

        There are some catches to this process. First the warehouse will only hold your goods for a few weeks before throwing them out. If they throw them out, you lose your money. This date is shown in your account. Second, not every taobao vendor is good about quickly shipping items. So now you have a dilemma. What do you do if two weeks have gone by and one of your items has not arrived??? You are going to be forced into sending the DHL package without that item. Then it will arrive a week later, you won’t want to pay $30 shipping to get it. So you will let it get thrown away. On the plus side, it is almost always some cheap item that does not show up in time.

        PS — Don’t start this process over Chinese New Year. All of the vendors are going to be on vacation and there will be large delays before they ship your stuff to the warehouse. Wait until the holiday is over.

        Maybe Jean-Luc will do a nice instructional post on this with lots of pretty pictures.

        1. It’s the first time I hear about that method. I always thought the only way to order from outside of China was to use a Taobao forwarder.

          1. Taobao built their own forwarder about five years ago. Too many people were getting ripped off by the third party ones.

      2. >1) How do you get started developing on a
        >board with no info / limited / outdated SDK?

        All I had originally was an IP camera that reported that it was a Cortex A7 from /proc/cpuinfo.. I had never seen a QFN A7 before so I started pulling apart the kernel that was on it.

        I got mainline booting to shell, gpio and pinctrl working without anything but the IP camera and after that the u-boot and kernel source turned up and then by searching for the register descriptions in there it was possible to see the ethernet is a variation of macb that is in the kernel already, the usb is variation of the faraday usb host etc.
        The register names also helped find two datasheets with registers for some really old chips (ARM9 satnav chip) that contained a lot of shared blocks.

      1. Sigmastar is still around. They are a fully owned subsidiary of mediatek but it seems mediatek only wanted the TV part of the company so they left the remainder to do their own thing.

  1. Good job Daniel!
    This tiny module looks nice. It’s probably hard to integrate it onto a small board as is though. However I’m now seeing this 88-pin chip, which looks easy to solder 🙂 Probably that by keeping roughly the same layout you can make your own board with ethernet/usb/wifi on the other side and GPIOs on one or two sides. These hacker-friendly SoCs could get a great success among hobbyists.

    1. Thanks Willy.

      I actually planned to make a piggy back board for the $6 version of these modules over the weekend… then I thought maybe I’d make a really stupid cluster out of these things as there are two ethernet controllers, so you could have one as an internal cluster network with a switch on the board and then the other as a physical plug. So I looked for 5 or 9 port switches with more than one RMII port for a few hours.

      Then I remembered macb is still a bit broken for mstar/sigmastar at the moment and decided to try to fix that first. 😀

      1. hehe , usual long dependency chain 🙂

        It’s always difficult to decide how to assign interfaces. Some people want two physical ones (it used to be my case), some want a switch (it’s been my case as well). Some boards use switch chips featuring two RMII ports so that you can route your ports to whatver port group you want. BTW, I seem to remember that there are cheap and easy to use chips at realtek.

        1. I have a bunch of realtek switches for the stupid cluster board I designed that was basically 8 breadbees on a board.. The trouble is they only have ports with the PHY which would mean using the PHY port on the SoC for the internal switch and then adding external PHYs for all of the ports.

          Microchip have some with PHYs and RMII ports but it’s 2 RMII ports + 3 or more PHY ports. I think that might work for the worlds worse HA setup with two SoCs.

      2. I’m getting increasingly excited about these little SoCs the more I learn about them. Please remember to send anything you want to have in 5.12 soon though: It’s almost -rc6, and I see you have a number of things in github that would be candidates for upstream.

        Regarding the “stupid cluster” idea, you could make it even more hilarious by using a USB hub connected to the USB-OTG ports, with one machine acting as a virtual ethernet switch with a USB host port. I couldn’t find out from the product briefs if the USB ports support OTG, obviously it wouldn’t work without that.

        1. Hi Arnd,

          I think everything is a bit backed up on getting the clock drivers in. I still haven’t worked out how to get things that probe before the main “mpll” PLL block to work properly without having clock names in the DT and I was told not to put them in the DT. So a bit stuck there.
          I will try to break out some of the stuff can go before that.

          The previous members of this family a have a MUSB device controller alongside the host controller and there is a mux to device which gets connected to the port. These might be the same but I can’t see the interrupt for the MUSB controller in the vendor code for these chips so maybe they dropped it. I think it’s still there on the IP camera parts.

          These have 3 serial ports I think.. so you could daisy chain the serial ports and run SLIP over them and still have a console on each 😀

        2. Ah that’s another amusing approach I hadn’t thought about. In the past my idea for my build farm was to daisy-chain devices using USB-to-OTG and emulating ethernet there (it requires zero extra device, only cables). Arguably this is ugly 🙂

          Daniel, there were numerous switch chips from Micrel (now Microchip I think so they may be the ones you were talking about), Marvell and Broadcom (both expensive). There’s AR8327 which provides 2 RGMII/RMII ports and 5 PHY ports. It might be too expensive for the job since gbe-capable. I also remember finding some cheap “Vitesse” chips in some entry-level switches. I also remember having seen yet another brand in cheap devices but I really can’t remember which one.

    1. You are going to have a long wait for an opensource modem that isn’t GSM.
      I think the only thing you can really do is make sure all of the data you send via the modem is properly secured.

      1. I think quectel modems have an internal application processor and the modem processor and the linux thingy is only on the AP of the modem, not the actual radio controller.

      2. oh yeah i knew that! at least the modem kernel can be opensource(and trusted)! thats good news! half of the job.

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