[Microbit-Python] This happens when your code is "too big" (more than 8kB)

[Nicholas H.Tollervey]

Addressing this would probably help:

https://github.com/bbcmicrobit/PythonEditor/blob/master/static/js/python-main.js#L112

The same probably applies to uflash too (I've not forgotten your PR
L0CARD - I'm spending this weekend catching up on micro:bit things).

Pull requests most welcome. ;-)

N.

On 01/07/16 10:15, James Sheppard wrote:
> Hello everyone
> 
> I thought people might be interested to know what happens when the
> MicroPython code being flashed onto a micro:bit is more than 8kB.
> 
> This analysis was done on a hex file generated by the MicroPython Editor
> on https://www.microbit.co.uk/ bulked out with ~200 lines of comments. 
> 
> If you’ve never opened up a .hex file to take a look, now could be the
> right time…
> 
> (You might find https://en.wikipedia.org/wiki/Intel_HEX useful to refer to.)
> 
> The first line in the file looks like this:
> 
> :020000040000FA
> 
> Which sets the base address of data to be flashed to 0x0 0000.
> 
> Lines then follow that start with
> 
> :10XXXX00...
> 
> which indicates the data to be written to 0x0 XXXX
> 
> Keep going, and eventually you’ll see
> 
> :020000040001F9
> 
> which sets the base address to 0x1 0000.
> 
> Then more data.
> 
> Then
> 
> :020000040002F8
> 
> which sets the base address to 0x2 0000.
> 
> Then more data.
> 
> Then
> 
> :020000040003F7
> 
> (0x3 0000)
> 
> and yet more data. So far this has all been MicroPython data (over
> 200kB). Your code is next.
> 
> You’ll see
> 
> :020000040003F7
> 
> again, which sets the base address to 0x3 0000 again (i.e. no change).
> User code starts at 0x3 E000 with the bytes 4D 50 54 32 (“MPT2”) then
> the script itself.
> 
> :10E000004D505432...
> 
> If there's more than 8kB of user code, you’ll see the address overflow
> from 0x3 FFF0 to 0x3 0000
> 
> :10FFF000...
> :10000000...
> 
> During flashing of the hex file to the micro:bit, this causes the
> MicroPython hex at these addresses to be overwritten - who knows what’s
> just been trampled over!
> 
> Cheers,
> James
> 
>  
> 
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