Why is the firmware size for STM32 VL Discovery much smaller than other boards

[espruino-discuss]

Posted at 2020-10-04 by Ragtime

I was browsing the 2v07 firmwares downloaded from https://www.espruino.com/Download, and found out that Espruino firmware on STM32 VL Discovery is only about 116.3 KB while for other boards at least around 220 KB (even without hardware modules like WiFi, Bluetooth, etc.).
Is that because of the size of fundamental libraries used for supporting STM32 VL Discovery is much smaller?

Best regards

[espruino-discuss]

Posted at 2020-10-04 by AkosLukacs

Because there is no more space :)
The VL Discovery has only 128k flash, and there is some space reserved for saving code, so the board can run code standalone.

You can compare the board files, for example PICO vs VL Discovery. That Discovery board only includes neopixel, and has SAVE_ON_FLASH - removing bunch of features. While the PICO has USB, networking, graphics, encryption etc libraries built-in.

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Posted at 2020-10-04 by Ragtime

Aha! Thank you so much. Your example is very helpful!

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Posted at 2020-10-04 by Ragtime

The VL Discovery has only 128k flash, and there is some space reserved for saving code, so the board can run code standalone.

Do you know where the space for saving code is reserved? Because I haven't found 'saved_code' defined in the board definition file STM32VLDISCOVERY.py.

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Posted at 2020-10-05 by @gfwilliams

STM32 is one of the very first boards Espruino ever ran on, so the code to handle them is a bit 'legacy' - I believe it is here: https://github.com/espruino/Espruino/blob/master/scripts/build_platform_config.py#L113

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Posted at 2020-10-05 by Ragtime

Interesting! Thanks :D