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by amahajan 1905 days ago
I have been using these modems at work, specifically the EC25/EC20. They come with linux with some limitations. These modems are typically meant for IOT devices and you can get them for ~ 16/18 USD (or even lower). 4G/3G/2G, with around 128/256M flash and 128M RAM and 1.3GHz Arm Cortex A7. They are pretty powerful for their size, cost, current consumption and usability. Almost all such parts can be hacked across manufacturers see

https://i.blackhat.com/USA-19/Wednesday/us-19-Shupeng-All-Th...

You can get the Linux distribution and a compilation environment for these from the manufacturer (source code). You may need to have a business account though.

Linux binaries can be used on these, we have tried code compiled in Rust, Go etc cross compiled for arm target and used on these targets, though the primary development is still in c / c++

They come with a bit dated OPENSSL, though you can compile to a newer version and use that. SQLITE comes built in

There is support for peripheral access I2C, SPI, SDIO, I2S etc. You could possibly create a simple gaming console with LTE connectivity, since the SPI can drive a TFT and there are IOs for keypad and I2C for touch and accelerometer, gyro etc

Actual modem FW is not available, since that would be Qualcomm properietary!

1 comments

I'm a bit confused: does the manufacturer provide a toolchain to compile and run binary code on something that is not advertised as a SOM/SOC, but only as an lte modem?
Yes that is true in fact even the most basic modems in their line up for 2G can be used as an Application processor rather than as a plain modem.

In this case however it is more like a complete build environment that includes the Linux distribution, GCC and other relevant Linux libraries etc for the distribution. The real FW for cellular modem is likely never exposed since that may run on a DSP core or an ASIC sub system