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More notes on .hex size protection

This commit is contained in:
cbbrowne 2016-12-01 16:24:03 -05:00
parent 1f290f6213
commit b787ed9dc6
1 changed files with 16 additions and 3 deletions

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@ -1318,14 +1318,27 @@ You probably don't want to "brick" your keyboard, making it impossible
to rewrite firmware onto it. Here are some of the parameters to show
what things are (and likely aren't) too risky.
- If a keyboard map does not include RESET, then, to get into DFU
- If your keyboard map does not include RESET, then, to get into DFU
mode, you will need to press the reset button on the PCB, which
requires unscrewing some bits.
requires unscrewing the bottom.
- Messing with tmk_core / common files might make the keyboard
inoperable
- Too large a .hex file is trouble; `make dfu` will erase the block,
test the size (oops, wrong order!), which errors out, failing to
flash the keyboard
flash the keyboard, leaving it in DFU mode.
- To this end, note that the maximum .hex file size on Planck is
7000h (28672 decimal)
```Linking: .build/planck_rev4_cbbrowne.elf [OK]
Creating load file for Flash: .build/planck_rev4_cbbrowne.hex [OK]
Size after:
text data bss dec hex filename
0 22396 0 22396 577c planck_rev4_cbbrowne.hex
```
- The above file is of size 22396/577ch, which is less than
28672/7000h
- As long as you have a suitable alternative .hex file around, you
can retry, loading that one
- DFU tools do /not/ allow you to write into the bootloader (unless
you throw in extra fruitsalad of options), so there is little risk
there.