On Sun, Jul 13, 2025 at 06:07:56AM -0000, Michael van Elst wrote: > m...@netbsd.org (Emmanuel Dreyfus) writes: > > >Another test, outputing "hello world!\r\nxx" (two x) and then > >"HELLO WORLD!\r\nX" (one X) > > >The display is (mind the leading space) > > ELLO WORLD! > >Xx > > > You could try to dump the bytes you receive instead of deducing > them from the visible output. > > If that's real hardware, I'd guess that the symptoms come from > a hardware problem like a missing ground.
Serial lines usually rest at the mark state, (I.E. 1), so I'd be suspicious that both of the spurious characters mentioned, 'x' and, 'o', contain runs of four binary 1s: x = 01111000 o = 01101111
