Macro cortex_m::bkpt

macro_rules! bkpt {
    () => { ... };
    ($e:expr) => { ... };
}

Puts the processor in Debug state. Debuggers can pick this up as a "breakpoint".

Optionally, an "immediate" value (in the 0-255 range) can be passed to bkpt!. The debugger can then read this value using the Program Counter (PC).