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4 years, 3 months ago.

SSL support in u-blox C027?

Hi, does anyone have any experience using SSL in u-blox C027?

Currently I am considering two candidates: Mbed TLS and Wolf SSL.

A primary concern for me is the small RAM available in this device, specifically, only 32KB for own code, and another 32 KB for library. Also other values like documentation should also be considered.

Anyone is willing to share some experience or insights about existing SSL libraries? I am also open to other alternatives.

Question relating to:

The u-blox-C027 is a complete starter kit that allows quick prototyping of a variety of applications for the Internet of Things. The application board has a MAX-M8Q GPS/GNSS receiver and ...
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2 Answers

3 years, 11 months ago.

I have a C027 with a SARA G350 modem which (according to the u-blox cellular line card at https://www.u-blox.com/sites/default/files/products/documents/Cellular_LineCard_%28UBX-13004714%29.pdf) supports embedded SSL.

However, the AT commands "AT+USECPRF=?" and "AT+USECMNG=?" both return "CME Error: unknown" which indicates the commands are not supported.

Is there something I'm missing or is it not possible to do SSL with this modem?

4 years, 3 months ago.

The C027 is based on the LPC1768 which has 64kB of RAM organized in two 32kB sections. One 32kB section is used for normal variables the other section will contain variables from the Ethernet interface or the USB stack if you pull them in. You can also use this section for your variable if you assign them using pragmas.

The cellular module mounted of the C027 also has built-in SSL commands e.g. support for FTP or HTTP. You might want to explore to use those commands and extend the API of the current mbed driver library. You can get detailed information about the SSL features and in the AT commands of the cellular module.

https://www.u-blox.com/images/downloads/Product_Docs/u-blox-ATCommands_Manual_%28UBX-13002752%29.pdf

Hi Ammann, thanks for your quick reply. Sorry I was busy with something else the last few days and didn't follow this question. Regarding your answer I still have a few questions.

1). Which mbed driver library are you referring to? The C207_Support library?

2). I realized it is possible to extend that library, but can't I use an existing SSL library, shouldn't it be easier? If it is possible, which SSL library would you recommend?

Thank you in advance.

posted by Xinlei Cao 07 May 2015

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