STDIO only accepting ASCII due to signed char?


I’m currently trying to write an ROP chain as an example on how the Jiminy-board might be abused. During that research I noticed that RIOT can only accept ASCII chars, but not just any arbitrary hex value. The isr_pipeline uses chars, which on the avr platform, default to signed chars. Therefore RIOTs behaviour becomes, at least in my opinion, kind of undefined when sending e.g. 0xff.

Is there a specific reason for using signed chars instead of unsigned ones?

Best regards, Steffen