On Sun, 13 Jul 2025, Emmanuel Dreyfus wrote:
Using ktrace on screen, on the receiving end:
" "
"EL"
"L"
"O"
" "
"W"
"O"
"RL"
"D"
"!\r\n"
"X"
"x"
On first insight, I thought the first output was just discarded
and the trailing x was just there because the same buffer was used.
But on first output I give usbd_setup_xfer() a 16 characters length,
on second output, 15 characters. I cannot make up an explanation why
the trailing x is there. Perhaps the receiving kernel does some
processing?
If that's real hardware, I'd guess that the symptoms come from
a hardware problem like a missing ground.
The link works find with other usages.
Does the link have working HW flow control (RTS/CTS)? If only 3 wires are
active (Rx/Tx/GND), then you'll have to set very low speeds.
-RVP
