ST-Link cable length

[Moritz1]

Hello,

does anyone know what the maximum cable length is for the ST-Link programmer (20-pole ribbon cable)?

Maybe someone has experience with this?

Is it possible to bridge longer distances, e.g. 50 metres? (not the USB cable, but the 20-pole ribbon cable).

[Uwe Bonnes]

Use the bootloader and the serila connection for programming. Even slowing down SWD/JTAG may not help, as reflections can easily produce ghost edges that will get SWD/JTAG communication out of order. Otherwise series termination all signals at the source will lower reflections and additional ground line will reduce ground bounce.